Range Rover Temp Sender Thread Size?
Discussion
asd2001 said:
So, an easy 5 minute fit then gauge consistently reading about 5 degrees lower than rovergauge. Seems to be well bled, any ideas or just a case of live with it?
Looks like I’ve got a 74 degree thermostat, with temperatures sitting about 75 on a run. Views on if it worth the bother of changing?
I strongly advise getting rid of that 74 degree thermostat and replacing it with the correct value of 88c, at this point its important to understand the true function of thermostat.Looks like I’ve got a 74 degree thermostat, with temperatures sitting about 75 on a run. Views on if it worth the bother of changing?
A thermostat actually only has has two jobs:
1. To aid rapid engine warm up, which is very important
2. To regulate the correct coolant temperature when the car is driven at speed but not at idle
Keep in mind liquid cooled engines don't tend to overheat when the car is on the move, this is because of airflow, if you've ever ridden a motorcycle and especially on a cold day you'll know air flow even at just 30mpg is significant, at normal road speeds there's a hurricane force wind blast driving its way through your radiator. A catastrophic loss of coolant aside, if a car is going to overheat it'll happen at very low road speeds and at idle where there is little of no airflow, this is precisely why cars tend to overheat in traffic jams.
Your Chimaera is designed to idle with it's coolant cycling between 92c (rad fans cycle on) and 88c (rad fans cycle off), of course like this a correct value 88 degree thermostat will be just as open as your 74 degree thermostat, ie both will be fully open! So if you think about it your 74 degree thermostat is making absolutely no contribution towards reducing the chances of your Chimaera overheating in the traffic jam scenario.
Because the coolant system is designed around an optimum safe running/idle temperature of 88c it wouldn't matter a jot if you fitted a 63c thermostat, a 74 degree thermostat or an 88 degree one... all these thermostat values would be fully open at idle and fully open is fully open! So unless you were stupid enough to fit a thermostat of a value higher than the maximum safe operating temperature the thermostat is going to do nothing to reduce your coolant temps in the critical traffic jam scenario...... which is the only real situation where you're ever at potential risk of overheating!
We can now clearly see the ability of your coolant system to maintain a safe coolant temperature at idle has absolutely nothing to do with the thermostat value, but is entirely governed by the following:
1. The overall capacity of your entire cooling system
2. The ability of your water pump to push a sufficient volume of coolant through the cooling system
3. The size of your radiator and the effective flow of coolant through it
4. The amount of air your radiator fans can pull through your radiator core and the coolant temperature they are activated at
The correct way to choose a thermostat is to match its value to the optimum safe coolant temperature when the engine is at idle, as previously stated your engine is designed to idle at a regulated 88-92c so the correct value thermostat for our Rover V8 engined TVRs is 88c. If you fit a lower value thermostat all that will happen is your coolant will take longer to reach the correct temperature, eventually even with a 74 degree thermostat and after a period at idle your engine will still reach the 88-92c window.
However, with a 74 degree thermostat fitted even if it's only a moderately cold day and you find yourself travelling at speed shortly after a cold start because your thermostat is opening too early wind blast through your radiator will mean the coolant temp will unlikely ever reach the point where the ECU is configured to finish applying the last stages of it's cold start enrichment..... so you'll just be wasting fuel unnecessarily!
I run an 88 degree thermostat because this is the correct value thermostat for this engine, in this warmer weather my very accurate Canems software displays my true coolant temperatures as follows:
1. 88-92c at idle - Thermostat fully open so my coolant temp entirely and exclusively governed by coolant system capacity and rad fan cycle temps
2. 86-87c at speed - Thermostat just starting to close as it trys to maintain the optimum operating coolant temp of 88c
In the cooler months and even with my 88c thermostat fitted I tend see 82-85c out on the motorway, so my 88 degree thermostat is now fighting hard against the slightly over efficient Chimaera cooling system and freezing wind blast in a bid to hit the the optimal target temperature of 88c.
I guarantee you if I had a too early opening 74 degree thermostat and I joined the motorway soon after cold start that super cooled wind blast and the slightly over efficient Chimaera cooling system would win hands down, like this I'd be running my engine at a far from optimum 65-70c at best and even on a warm day I would unlikely ever come close to the optimum operating temp off 88c until I slowed and spent some time at idle.
So now we know a 74c thermostat does absolutely nothing to stop overheating and indeed will very likely only mean your engine runs far too cool, the evidence clearly tells us the correct thermostat to fit to your Chimaera is one of a 88c value. Anything else just shows a disregard of the optimum safe operating temperature the designer specified, a fundamental lack of understanding of how a cooling system actually works, and the function a thermostat plays in that system.
Edited by ChimpOnGas on Wednesday 10th July 11:32
If you're worried about liner slip due to excessive engine temperature it's important understand liquid cooled engines don't reach their peak operating temperature on the move, they reach it at idle and just after the radiator fans are set to come on as there will be a slight response delay before coolant temps begin to fall.
And I'm afraid to say you're not going to lower your peak coolant temperature by replacing the correct 88c thermostat with an 82c one because quite simply both thermostat values will be very much fully open at idle
Q: How hot does the coolant in a Rover V8 TVR become at it's peak with an 88 degree thermostat fitted when the engine is at idle?
A: 92-95c - This is dictated by the coolant capacity, the size of the heat exchanger (the radiator), the volume of coolant moved by the water pump and the activation temperature of the radiator fans... It is not governed by the thermostat value because clearly an 88c thermostat will be fully open long before peak coolant temp is reached
Q: How hot does the coolant in a Rover V8 TVR become with an 82 degree thermostat fitted when the engine is at idle?
A: The exact same 92-95c - Again this is dictated by the coolant capacity, the size of the heat exchanger (the radiator), the volume of coolant moved by the water pump and the activation temperature of the radiator fans... It is not governed by the thermostat value because just like the 88c thermostat an 82c thermostat will be fully open long before peak coolant temp is reached
In a TVR Chimaera the moment of peak coolant temperature may for just a second or so spike at 95c, this is perfectly safe and should be considered normal. My experience is with my Chimaera fitted with an 88c thermostat even on the hottest day and at idle my coolant never exceeds an absolute and very brief maximum of 93c, after that my radiator fans very effectively regulate my coolant temps between this absolute max of 93c down to the absolute minimum of 86c.
1. Fan activation = 90c
2. Peak coolant temp = 93c
3. Fan deactivation = 86c
4. Min - Max operating temp window = Just 6c - This is an excellent result, the only way to achieve a tighter window would be to fit an electric water pump
5. Coolant temp at speed on a hot day = 86-87c
6. Coolant temp at speed on a cold day = 80-83c
And here's what it would look like with an 82c thermostat fitted:
1. Fan activation = 90c - No different to it is with an 88c thermostat fitted because both stats will be fully open
2. Peak coolant temp = 93c - No different to it is with an 88c thermostat fitted because both stats will be fully open
3. Fan deactivation = 86c - No different to it is with an 88c thermostat fitted as the fan-off temp is set the same
4. Coolant temp at speed on a hot day = Maybe 83c ish
5. Coolant temp at speed on a cold day = Almost certainly an undesirable cool 70 - 75c
6. Min - Max operating temp window = 10c in hot weather and a whopping 20c in cooler weather
So lets look at what you get that's different if you fit an 82c thermostat over the correct 88c thermostat:
We can now clearly see there are only disadvantages to running an 82c thermostat and no real advantages whatsoever!
Keep in mind the objective when designing a cooling system for an internal combustion engine is to create the tightest safe operating temperature window as possible under all operating conditions, the tighter you can make the window the better you have achieved your brief. The word safe is an important one, the peak operating temperature that occurs 1-2 seconds after fan activation will be carefully set by the designer well below the known point where issues may arise.
The designer wants the engine to reach is optimum safe running temperature as fast as possible as this saves fuel, reduces engine wear and lowers emissions, he then wants to pin that optimum safe running temperature as tightly as he possibly can to his target mean operating temp from idling on the hottest day to driving on the motorway at speed on the very coldest winter day.
Quite clearly if a TVR Chimaera owner wants to achieve the same goal he is way way better off fitting an 88c thermostat that an 82c one
And I'm afraid to say you're not going to lower your peak coolant temperature by replacing the correct 88c thermostat with an 82c one because quite simply both thermostat values will be very much fully open at idle
Q: How hot does the coolant in a Rover V8 TVR become at it's peak with an 88 degree thermostat fitted when the engine is at idle?
A: 92-95c - This is dictated by the coolant capacity, the size of the heat exchanger (the radiator), the volume of coolant moved by the water pump and the activation temperature of the radiator fans... It is not governed by the thermostat value because clearly an 88c thermostat will be fully open long before peak coolant temp is reached
Q: How hot does the coolant in a Rover V8 TVR become with an 82 degree thermostat fitted when the engine is at idle?
A: The exact same 92-95c - Again this is dictated by the coolant capacity, the size of the heat exchanger (the radiator), the volume of coolant moved by the water pump and the activation temperature of the radiator fans... It is not governed by the thermostat value because just like the 88c thermostat an 82c thermostat will be fully open long before peak coolant temp is reached
In a TVR Chimaera the moment of peak coolant temperature may for just a second or so spike at 95c, this is perfectly safe and should be considered normal. My experience is with my Chimaera fitted with an 88c thermostat even on the hottest day and at idle my coolant never exceeds an absolute and very brief maximum of 93c, after that my radiator fans very effectively regulate my coolant temps between this absolute max of 93c down to the absolute minimum of 86c.
1. Fan activation = 90c
2. Peak coolant temp = 93c
3. Fan deactivation = 86c
4. Min - Max operating temp window = Just 6c - This is an excellent result, the only way to achieve a tighter window would be to fit an electric water pump
5. Coolant temp at speed on a hot day = 86-87c
6. Coolant temp at speed on a cold day = 80-83c
And here's what it would look like with an 82c thermostat fitted:
1. Fan activation = 90c - No different to it is with an 88c thermostat fitted because both stats will be fully open
2. Peak coolant temp = 93c - No different to it is with an 88c thermostat fitted because both stats will be fully open
3. Fan deactivation = 86c - No different to it is with an 88c thermostat fitted as the fan-off temp is set the same
4. Coolant temp at speed on a hot day = Maybe 83c ish
5. Coolant temp at speed on a cold day = Almost certainly an undesirable cool 70 - 75c
6. Min - Max operating temp window = 10c in hot weather and a whopping 20c in cooler weather
So lets look at what you get that's different if you fit an 82c thermostat over the correct 88c thermostat:
- A tiny 3c difference when driving on a hot day, so small as to make fek all difference
- An engine that on a cool day will run a full 10c below the temperature it's designers intended
- A max - min operating temperature window that's much wider than if you had fitted the correct 88c thermostat
- Much slower warm up times especially in cold weather
- A far greater time spent in warm up enrichment so higher emissions, higher fuel consumption, and accelerated engine wear due to carbon fouling of plugs/combustion chambers/valves and of course bore wash
We can now clearly see there are only disadvantages to running an 82c thermostat and no real advantages whatsoever!
Keep in mind the objective when designing a cooling system for an internal combustion engine is to create the tightest safe operating temperature window as possible under all operating conditions, the tighter you can make the window the better you have achieved your brief. The word safe is an important one, the peak operating temperature that occurs 1-2 seconds after fan activation will be carefully set by the designer well below the known point where issues may arise.
The designer wants the engine to reach is optimum safe running temperature as fast as possible as this saves fuel, reduces engine wear and lowers emissions, he then wants to pin that optimum safe running temperature as tightly as he possibly can to his target mean operating temp from idling on the hottest day to driving on the motorway at speed on the very coldest winter day.
Quite clearly if a TVR Chimaera owner wants to achieve the same goal he is way way better off fitting an 88c thermostat that an 82c one
I think we will have to agree to disagree on this one.
The standard rad fan switch is set to bring the fans in around 90c so it doesn't matter if you fit an 82c thermostat to your engine or an 88c thermostat both stats will be fully open well before the fans come on, and both engines will peak at 93c - 95c no matter which of these two thermostat values are fitted and both engines absolutely need radiator fans.
The man who runs an 82c thermostat is still going to hit a peak temp of 92 - 95c, the exact same 92 - 95c as the man who runs an 88c thermostat, so how a 82c thermostat is going to reduce the risk of overheating is beyond me!
In average ambient temps the man who runs an 82c thermostat is going to be driving at speed at 82 - 83c where the man who runs an 88c thermostat fitted will see 86c -87c so what you're really getting with an 82c thermostat is coolant temps on a typical mild to hot day that are just just 4c cooler..... sorry to say it but 4c is nothing!
There's is absolutely no lowering of liner slip risk by running the engine this tiny 4c cooler, both 83c and 87c are absolutely 100% perfectly safe and massively lower than any point of danger.
All the 82c thermostat is really going to give you is:
1. Longer warm up times so poor/slower heater performance
2. Longer in cold start enrichment so higher emissions and more fuel use
3. Accelerated engine wear due to extended warm up times and unnecessary over enrichment
4. An engine that'll run way too cool in the winter months
I'd also love to put a Chimaera on a rolling road and do back to back power runs at 60c, 65c, 70c, 75c, 80c, 85c, 90c and 95c coolant temps... if the difference was more than half a horsepower I'd eat my hat!, if you did see any more than 0.5hp it'll be down to changes in intake air temps and AFR because at 60 - 65c you'll probably still be getting some cold start enrichment, the engine will have both a richer mixture and be enjoying cooler air intake temps too simply by virtue of having suffered less heat soak because it hadn't been running as long.
If people still think driving about with their coolant at 82 - 83c rather than 86 - 87c is any safer and makes the kind of additional power you can actually feel then by all means fit an 82c thermostat, just be aware when the winter comes you'll also be driving about way too cool at 72 - 75c.
Finally don't kid yourself a 82c thermostat will do anything to protect your engine from overheating because when you inevitably come to a stop in traffic your coolant will rise above 82c within just a few seconds, remember your 82c thermostat is doing absolutely fek all after 82c as that's when it reaches its fully open position! When your fans cut in at 90c and your gauge peaks at 93c which is perfectly normal by the way, ask yourself if your fans had failed to chime in would your 82c thermostat have done anything to help save the day
The standard rad fan switch is set to bring the fans in around 90c so it doesn't matter if you fit an 82c thermostat to your engine or an 88c thermostat both stats will be fully open well before the fans come on, and both engines will peak at 93c - 95c no matter which of these two thermostat values are fitted and both engines absolutely need radiator fans.
The man who runs an 82c thermostat is still going to hit a peak temp of 92 - 95c, the exact same 92 - 95c as the man who runs an 88c thermostat, so how a 82c thermostat is going to reduce the risk of overheating is beyond me!
In average ambient temps the man who runs an 82c thermostat is going to be driving at speed at 82 - 83c where the man who runs an 88c thermostat fitted will see 86c -87c so what you're really getting with an 82c thermostat is coolant temps on a typical mild to hot day that are just just 4c cooler..... sorry to say it but 4c is nothing!
There's is absolutely no lowering of liner slip risk by running the engine this tiny 4c cooler, both 83c and 87c are absolutely 100% perfectly safe and massively lower than any point of danger.
All the 82c thermostat is really going to give you is:
1. Longer warm up times so poor/slower heater performance
2. Longer in cold start enrichment so higher emissions and more fuel use
3. Accelerated engine wear due to extended warm up times and unnecessary over enrichment
4. An engine that'll run way too cool in the winter months
I'd also love to put a Chimaera on a rolling road and do back to back power runs at 60c, 65c, 70c, 75c, 80c, 85c, 90c and 95c coolant temps... if the difference was more than half a horsepower I'd eat my hat!, if you did see any more than 0.5hp it'll be down to changes in intake air temps and AFR because at 60 - 65c you'll probably still be getting some cold start enrichment, the engine will have both a richer mixture and be enjoying cooler air intake temps too simply by virtue of having suffered less heat soak because it hadn't been running as long.
If people still think driving about with their coolant at 82 - 83c rather than 86 - 87c is any safer and makes the kind of additional power you can actually feel then by all means fit an 82c thermostat, just be aware when the winter comes you'll also be driving about way too cool at 72 - 75c.
Finally don't kid yourself a 82c thermostat will do anything to protect your engine from overheating because when you inevitably come to a stop in traffic your coolant will rise above 82c within just a few seconds, remember your 82c thermostat is doing absolutely fek all after 82c as that's when it reaches its fully open position! When your fans cut in at 90c and your gauge peaks at 93c which is perfectly normal by the way, ask yourself if your fans had failed to chime in would your 82c thermostat have done anything to help save the day
Edited by ChimpOnGas on Thursday 11th July 14:44
QBee said:
Shirley (he said, calling his daughter's mother in law) the purpose of the thermostat is to get the engine up to operating temperature, which will be the temperature at which the thermostat opens, as quickly as possible? It's job is to stop the water circulating through the radiator until it reaches that temperature.
And so you want the opening temperature of the thermostat to be the temperature at which you think the engine should be operating?
All we now need to know is the desired operating temperature of the engine, and we can fit an appropriate thermostat?
This is correct however there is one additional critical element to consider, which is driving time from a cold start before you exceed roughly 30mph. If you fit a thermostat of a lower than desirable value and join fast moving traffic too soon after cold start you are very likely to find the engine will take absolutely for ever to even reach optimum operating temp, indeed depending on the length of your journey and ambient temps it may never reach the optimum operating temp.And so you want the opening temperature of the thermostat to be the temperature at which you think the engine should be operating?
All we now need to know is the desired operating temperature of the engine, and we can fit an appropriate thermostat?
The thermostat value tells you when it's fully open but not when it starts to open, clearly a lower value thermostat will start to open earlier than a higher value one and if this is too early the engine is going too see the far cooler coolant held in the rad way too soon. This is especially true on a cold day, of course the thermostat will fight back by starting to close again but there will come a point where it begins to open once more.
And when it does start to open again the supper chilly high speed wind blast that's been pushing its way through your rad has now lowered the coolant temp in the rad even further, the engine receives this supercooled coolant and so the cycle continues. Eventually the coolant will reach the value stamped on the thermostat but it may well take so long you will have already reached your destination before this happens.
Contrary to popular misconception the cooling system on a Chimaera is actually over efficient, this compounds the issue for those insisting on fitting a too early opening lower than ideal value 82c thermostat, this is especially true in cold weather for those who do not need to pass through an urban environment after cold start and before they start to drive at speed.
As previously explained the objective is to get the engine to it's optimum operating temperature as fast as possible and hold it there as tightly as possible, this is made more difficult because wax type thermostats are quite slow in operation and a mechanical water pump spins at engine speed so the faster the engine turns the more coolant volume it shifts which in the case of assisting fast warm up times is the last thing you want.
This is why modern engines often have electric thermostats that are faster operating and more adaptable, its also why electric water pumps are becoming more popular too, for the first few minutes of warm up an electric pump may not run at all which greatly reduces the time it takes for the engine to reach its optimum operating temp. Given my old school wax type thermostat and mechanical water pump my warm up times are very fast, the coolant temp window my engine operates within is very tight too at 6c, I'd never come close to these results if I fitted and 82c thermostat especially during the cooler months as quite simply it'll be opening way too soon.
I run an 88c thermostat because 88c is a completely safe operating temperature for a Rover V8 engine and this is the coolant temp it's designers intended the engine to run at, my 88c thermostat helps my engine warm up faster than an 82c thermostat and puts me at no greater risk of overheating or liner shift than if I ran a 82c thermostat because no matter which of these two value thermostats I fitted my peak temp is still going to be 93 - 95c.
If trouble is going to come its not going to happen on the mid 80s its going to come higher than that and a 82c thermostat does nothing to stop the coolant heading that way any more than a 88c thermostat does because both thermostat values will have been long fully open, from this point and hotter controlling coolant temps becomes the job of your radiator fans not your thermostat!
I recommend an 88c thermostat and an adjustable Davies Craig staged fan controller, this combination works perfectly in all seasons and is all you need for safe fast warm ups and consistent well managed optimum coolant temps in all seasons
Edited by ChimpOnGas on Thursday 11th July 17:19
Sardonicus said:
1. Longer warm up times so poor/slower heater performance Once it hits circa 70/80 its already warm so how does your 88 reduce warm up time?
Read my above point on warm up times, if your thermostat opens too early warm up times will be extended because the engine is seeing the cooler coolant from the rad earlier.
2. Longer in cold start enrichment so higher emissions and more fuel use Like I say your hotter stat dont decrease this
Same, if your thermostat opens too early warm up times will be extended because the engine is seeing the cooler coolant from the rad earlier.
3. Accelerated engine wear due to extended warm up times and unnecessary over enrichment b
ks
Same, if your thermostat opens too early warm up times will be extended because the engine is seeing the cooler coolant from the rad earlier, this is a way more accurate statement than the power improving point, the power benefits of running an engine cooler is so minimal as to never ever be remotely detected by the driver.
4. An engine that'll run way too cool in the winter months Thats the job of the thermostat is it not? unless its failing or stuck open then yes
Again, you need to read my last post above if your thermostat opens too early warm up times will be extended because the engine is seeing the cooler coolant from the rad earlier. As previously stated the function of the thermostat is to get the engine up to optimum operating temperature as fast as possible, or at least the value stamped on your thermostat which in the case of an 82c thermostat is lower than optimum.
Read my above point on warm up times, if your thermostat opens too early warm up times will be extended because the engine is seeing the cooler coolant from the rad earlier.
2. Longer in cold start enrichment so higher emissions and more fuel use Like I say your hotter stat dont decrease this
Same, if your thermostat opens too early warm up times will be extended because the engine is seeing the cooler coolant from the rad earlier.
3. Accelerated engine wear due to extended warm up times and unnecessary over enrichment b
ksSame, if your thermostat opens too early warm up times will be extended because the engine is seeing the cooler coolant from the rad earlier, this is a way more accurate statement than the power improving point, the power benefits of running an engine cooler is so minimal as to never ever be remotely detected by the driver.
4. An engine that'll run way too cool in the winter months Thats the job of the thermostat is it not? unless its failing or stuck open then yes
Again, you need to read my last post above if your thermostat opens too early warm up times will be extended because the engine is seeing the cooler coolant from the rad earlier. As previously stated the function of the thermostat is to get the engine up to optimum operating temperature as fast as possible, or at least the value stamped on your thermostat which in the case of an 82c thermostat is lower than optimum.
And the good news is when the winter months come all you 82c thermostat people can see all this slower warm up and struggling to reach optimal operating temps happening before your very eyes. Because for the first time ever you now you have a sender that's better positioned in the inlet manifold and perfectly matched to your temp gauge.
At which point you may choose to fit an 88c thermostat and enjoy all the benefits it brings including a correctly performing heater, when the summer comes around again you may have promised yourself you'll go back to your 82c thermostat except what you'll find is your Chimaera runs no hotter with the 88c one so you'll leave it right where it is.
And like I say, thanks to me you can finally have the confidence in what you're seeing on your TVR gauge is accurate so this will give you all the confidence you need and all the evidence to prove I'm 100% right to promote the use of an 88c thermostat as specified by the manufacturers of the engine. The same manufacturers who believe me were (like all car makers to this day) absolutely scared shipless of warrantee claims from such schoolboy errors like running an engine too hot, because of this they erred on the side of caution and ran it far cooler than they knew it could tolerate.
At which point you may choose to fit an 88c thermostat and enjoy all the benefits it brings including a correctly performing heater, when the summer comes around again you may have promised yourself you'll go back to your 82c thermostat except what you'll find is your Chimaera runs no hotter with the 88c one so you'll leave it right where it is.
And like I say, thanks to me you can finally have the confidence in what you're seeing on your TVR gauge is accurate so this will give you all the confidence you need and all the evidence to prove I'm 100% right to promote the use of an 88c thermostat as specified by the manufacturers of the engine. The same manufacturers who believe me were (like all car makers to this day) absolutely scared shipless of warrantee claims from such schoolboy errors like running an engine too hot, because of this they erred on the side of caution and ran it far cooler than they knew it could tolerate.
Sardonicus said:
Optimum for what Dave emissions ? 
LPG your heater what?
Optimum for: LPG your heater what? 1. Good combustion efficiency
2. Correct heater performance
3. Being safely below a temperature that would put the engine in any kind of danger
Optimum is what the highly qualified engineers settled on after extensive testing using expensive test equipment in a controlled engine cell environment where variables such ambient and coolant temperatures can be precisely adjusted and measured.
This process would have included measuring power production, emissions, and most importantly engine durability, the objective being to find the repeatable point of failure in order that the manufacturer can specify an optimum safe operation temperature for the engine that kept them away from any risk of warrantee claims.
It would have been after all this that Land Rover settled on fitting an 88c thermostat, so that's good enough for me
asd2001 said:
Looks like I’ve got a 74 degree thermostat, with temperatures sitting about 75 on a run. Views on if it worth the bother of changing?
I advise fitting an 88 degree thermostat (supporting evidence provided)asd2001 said:
CoG, very clear. 88 degree thermostat on order.
You've made the right choice, assuming the fully open value is lower than radiator fan activation temperature a thermostat has absolutely no influence on the likelihood of your engine overheating or suffering liner slip, but your new 88c thermostat will open later so it will definitely help your engine warm up faster.... which is only a good thing After fitting the a TT6811-03 sender the 75c you recorded was accurate and as you say it was down to your too cool 74c thermostat, make no mistake running your engine at 75c is not ideal. The situation will only have been worse in the winter when the very early opening 74c thermostat would very likely have seen you driving at speed at 65 - 70c which will mean your ECU would have almost certainly still have been applying the last stages of cold start enrichment.
With your new 88c thermostat fitted you'll immediately exchange the too cool running temp of 75c for the far more suitable 86c, and for the avoidance of any doubt you are not going to overheat or suffer liner slip at 86c any more than you're going to overheat or suffer liner slip at 75c. But you will come out of cold start enrichment earlier with your new 88c thermostat so you'll use less fuel, and your heater will be far more effective when the cooler months come and you need it.
This is what a true 86c looks like on the gauge with the TT6811-03 sender fitted.
The above photo was taken at a slight angle but essentially what you'll see is a vertical needle, its standard industry practice for gauge makers set the correct running temp at the 12 o'clock position when they apply the scale to the gauge face so you can take further confidence fitting an 88c thermostat and running the engine at 86c is correct.
Of course at idle with the 75c thermostat fitted your coolant would still have reached fan activation temp (90c) and your coolant would have spiked at 93c before the fans started to drag that number down, this will be exactly the same with your 88c thermostat fitted because both thermostats will be fully open before the fans chime in.
So the 88c thermostat wont influence your peak coolant temp but it will save you fuel, keep your engine operating at the correct safe temperature and give you a far better performing heater when you need it in the cooler months. Essentially you've replaced all the negatives of your too cool thermostat with all the benefits of using the correct 88c thermostat as specified by the makers of the engine and without increasing the probability of overheating or liner slip one bit.
You've made the right choice
Just to wrap this thermostat business up its important to understand for those still running the Lucas 14CUX the thermostat is an important component integral to the correct functioning of this sophisticated electronic fuel injection system, and the thermostat value specified when the system was designed for the Rover V8 engine was 88c.
On page 26 of the factory cooling system manual it clearly states the value of the thermostat is 88c and outlines the testing procedure to check it is correctly functioning within a window of 85 - 89c.
This is further supported by the following factory thermostat spec that also included the Morgan Plus 8.
Now if you go to the factory fuel injection manual covering the Lucas 14CUX Hotwire system there is clear instruction that all checks must be completed with the coolant temperature between 80c - 95c, clearly this tells us this is the correct operating temperature window for the engine when warm and even more critically what the fuel injection system expects to see from a warm engine and considers the optimum operating temperature window.
It's quite clear operating the engine outside of this 80c - 95c window specified by the designers of 14CUX fuel system is not recommended, lower than 80c and the 14CUX will very likely still be applying a level of cold start enrichment and going above 95c is considered above the safe threshold and optimal 15c operating window.
Further more Mark Adams contributes the following in the ACT website....
"It is essential that the coolant thermostat is working correctly, especially on catalyst-equipped cars. The fuel injection system is optimised to provide accurate mixture control within normal temperature ranges."
And of course we now know from the factory fuel injection manual covering the Lucas 14CUX Hotwire system that the 'normal' temperature range is 80c - 95c.
Mark Adams goes on to sate....
"In the case of catalyst-equipped vehicles Oxygen/Lambda control does not start until the engine has reached 70 degrees Centigrade, therefore the absence of a thermostat may cause terminal cat damage."
https://www.actproducts.co.uk/2011/lucas-14cux-fue...
As previously stated the function of a thermostat is to help the engine reach its optimum operating temperature as quickly as possible which we now know to be 80c - 95c as specified by the engine manufacturer and critically the designers of the electronic fuel injection system that feeds it.
We also now know to achieve the 80c - 95c optimum operating temperature Land Rover working in partnership Lucas specified an 88c thermostat, this is what I mean when I say the thermostat is a an important component integral to the correct functioning of the electronic fuel injection system.
Of course it's entirely up to the readers of this post if they decide they know better and choose to ignore the fact an 88c thermostat was specified and the 80c - 95c optimum operating temperature window was clearly laid out by the engine manufacturer and the designers of the electronic fuel injection system, but be aware the 14CUX while very out of date by modern standards is still actually a very sophisticated system and for it to work correctly it needs to operate as designed.
Despite the fact the thermostat value the designers specified was 88c I'm not here to tell you you absolutely must fit an 88c thermostat, all I'm doing is presenting the component and operating specifications clearly communicated by the designers and manufacturers of the system. With this unarguable factual evidence laid before us you can of course choose to do with it what you will, but personally I'd recommend paying close attention to what the manufacturers of the engine and the designers of the electronic fuel injection system are saying/specifying because one thing is for sure..... they're not publishing this information for fun
At least with the TT6811-03 temp sender fitted you'll finally easily and reliably be able to see if you are operating your engine inside or outside of the important 80c - 95c optimum operating temperature window Land Rover and Lucas specified, as such I now feel my attempts to help the TVR Chimaera community on this one can be considered concluded.
Hope it helps chaps
On page 26 of the factory cooling system manual it clearly states the value of the thermostat is 88c and outlines the testing procedure to check it is correctly functioning within a window of 85 - 89c.
This is further supported by the following factory thermostat spec that also included the Morgan Plus 8.
Now if you go to the factory fuel injection manual covering the Lucas 14CUX Hotwire system there is clear instruction that all checks must be completed with the coolant temperature between 80c - 95c, clearly this tells us this is the correct operating temperature window for the engine when warm and even more critically what the fuel injection system expects to see from a warm engine and considers the optimum operating temperature window.
It's quite clear operating the engine outside of this 80c - 95c window specified by the designers of 14CUX fuel system is not recommended, lower than 80c and the 14CUX will very likely still be applying a level of cold start enrichment and going above 95c is considered above the safe threshold and optimal 15c operating window.
Further more Mark Adams contributes the following in the ACT website....
"It is essential that the coolant thermostat is working correctly, especially on catalyst-equipped cars. The fuel injection system is optimised to provide accurate mixture control within normal temperature ranges."
And of course we now know from the factory fuel injection manual covering the Lucas 14CUX Hotwire system that the 'normal' temperature range is 80c - 95c.
Mark Adams goes on to sate....
"In the case of catalyst-equipped vehicles Oxygen/Lambda control does not start until the engine has reached 70 degrees Centigrade, therefore the absence of a thermostat may cause terminal cat damage."
https://www.actproducts.co.uk/2011/lucas-14cux-fue...
As previously stated the function of a thermostat is to help the engine reach its optimum operating temperature as quickly as possible which we now know to be 80c - 95c as specified by the engine manufacturer and critically the designers of the electronic fuel injection system that feeds it.
We also now know to achieve the 80c - 95c optimum operating temperature Land Rover working in partnership Lucas specified an 88c thermostat, this is what I mean when I say the thermostat is a an important component integral to the correct functioning of the electronic fuel injection system.
Of course it's entirely up to the readers of this post if they decide they know better and choose to ignore the fact an 88c thermostat was specified and the 80c - 95c optimum operating temperature window was clearly laid out by the engine manufacturer and the designers of the electronic fuel injection system, but be aware the 14CUX while very out of date by modern standards is still actually a very sophisticated system and for it to work correctly it needs to operate as designed.
Despite the fact the thermostat value the designers specified was 88c I'm not here to tell you you absolutely must fit an 88c thermostat, all I'm doing is presenting the component and operating specifications clearly communicated by the designers and manufacturers of the system. With this unarguable factual evidence laid before us you can of course choose to do with it what you will, but personally I'd recommend paying close attention to what the manufacturers of the engine and the designers of the electronic fuel injection system are saying/specifying because one thing is for sure..... they're not publishing this information for fun
At least with the TT6811-03 temp sender fitted you'll finally easily and reliably be able to see if you are operating your engine inside or outside of the important 80c - 95c optimum operating temperature window Land Rover and Lucas specified, as such I now feel my attempts to help the TVR Chimaera community on this one can be considered concluded.
Hope it helps chaps
I totally understand it's tempting to believe our engines are significantly different from the Rover V8 fitted to a Range Rover or Discovery, but the truth is this just isn't the case, in all the important aspects and perhaps with the exception of the stroked 5.0 litre a Rover V8 in a TVR is really no different to those installed in the Land Rover vehicles.
Even the 5.0 litre has the exact same architecture, water jacket volumes, water pump, and as we all know the radiator TVR used on Chimaeras was just a Range Rover rad with some very minor changes to the hose outlet angles. Ok so compression ratio is going to have a bearing on heat production for sure, but I've said it hundred times now so I'll say it again... "the peak coolant temperature seen by your engine (no matter which capacity it is) will always be after the thermostat (even an 88c thermostat) has fully opened".
Once this is understood you'll soon realise why you can not solve overheating issues with a lower value thermostat, FACT!
When the fans chime in on your Chimaera the coolant will be at 90c and will reach an absolute maximum of 95c before the fans help bring the coolant temp down to roughly 86c, a 5.0 litre fitted with a low value thermostat is still going to hit that absolute maximum of 95c because all the thermostats being discussed here up to and including the correct 88c one will be fully open at the 90c fan activation point.
Now we know you can't solve overheating with a lower value thermostat we need to understand all you're going to do when you fit a lower value thermostat is force the engine to take longer to warm up to it's correct 80c - 95c operating window and in the winter months run cooler than the minimum 80c out on the open road when driving at speed, however if you fit the correct 88c thermostat your engine even on a warm day will run at a consistent 86/87c which is absolutely perfect and running 86/87c is of course totally safe and exactly what the 14CUX expects to see from a fully warmed engine!
With the correct 88c thermostat fitted your ECU will be managing the fuel metering and idle behaviour precisely as it's designers intended, at this point we should not kid ourselves, it's important we all accept while some chipping of the ECU went on at TVR this only really made small changes to the fuel map. The chips used by TVR did not alter the fact the 14CUX ECU is still looking to identify a fully warmed engine condition by virtue of the coolant temperature being within the 80c - 95c window as clearly laid out in the factory fuel injection manual, this critical perimeter is embedded within the core workings of the ECU does not change one bit by fitting a fuel chip!
So if you fit a lower value thermostat you're not protecting your engine from liner slip or overheating, all you're doing is forcing the engine to take longer to reach this very important 80c - 95c coolant temp window that tells the ECU to come out of cold start enrichment and that the engine is not exceeding 95c.
What also tends to happen with an 82c thermostat is you'll see a true 80c - 83c on a warm day when driving at speed which is actually fine, however come the cooler months the coolant tends to take for ever to get there and indeed what you typically see is 75c which is well below the 80c low limit of the correct operating temp the ECU uses to determine the engine is in its fully warmed running condition.
I've run both an 82c thermostat and and the correct 88c thermostat and I can 100% guarantee you the 88c thermostat gives better results, by switching from an 82c to an 88c thermostat you'll exchange 82c for 86c when driving at speed during the summer months, this 4c difference makes absolutely fek all difference so there are no disadvantages to running an 88c thermostat... FACT!
Where the totally summer safe 88c thermostat comes into its own is when ambient temps stat to cool a little, this will typically be from the autumn months on but even during the summer if you drive your TVR at night you'll immediately start to see the benefits of switching to the correct 88c thermostat. During cooler ambient temps with an 82c thermostat you will definitely suffer sub 80c running temps at speed which puts you outside what the ECU interprets as a fully warmed engine, and for heavens sake don't fit a 74 degree thermostat what ever you do.
Even with my 88c thermostat fitted my coolant temp will fall to 81c when on the motorway on a really cold day but the engine warms up so much faster than with my old 82c thermostat and unlike the 82c thermostat coolant temps never dip below the all important 80c lower threshold.
So there are no disadvantages in fitting the correct 88c thermostat, only benefits!
TVR may well have supplied the Chimaera with an 82c thermostat but they also fitted the engine with way too cool and highly inappropriate shrouded electrode NGK B7ECS, these two choices may be perfect if you're endurance racing and probably came as a consequence of what was needed on the Tuscan Challenge cars, but the uncomfortable truth is despite the fact as TVR owners we all think we are race car driving Gods we are just not using our cars the way a Tuscan Challenge TVR got used.
The 82c thermostat and highly inappropriate way too cool shrouded electrode NGK B7ECS spark plugs used by TVR is why we so often see this....
What we are seeing here is an NGK B7ECS spark plug that being a No7 is simply not getting hot enough to self clean, we are almost certainly also seeing it the problem has compounded by the fact the coolant is not reaching the 80c - 95c window so the ECU is still applying the last stages of cold start enrichment and is a classic symptom of the too lower value thermostat syndrome.
Change the plugs to a No6, and a set of good old cheap as chips BPR6ES plugs are just fine, then replace that 82c thermostat with the correct value 88c one and all this plug fouling goes away in an instant. Your TVR will idle better, run smother out on the open road and use less fuel, finally with your new found improved combustion efficiency will come more power too.
The reality is 99.9% of us drive our TVR Chimaeras on the road 99% of the time, we are not out there campaigning in the Tuscan Challenge going balls out a wide open throttle, we are driving normally on the public highway where we will inevitably experience periods at idle and everything in between. If you are choosing components for a race car they will be very different from those that deliver optimum performance on the road, you now just need to be honest with yourself as to the genuine type of driving to actually do and admit you yourself the Rover V8 in your TVR and the 14CUX electronic fuel injection system that meters fuel to it is really 99.8% all Rage Rover/Discovery.
All this may not be what the TVR community wants to hear, but thems the facts folks!
Even the 5.0 litre has the exact same architecture, water jacket volumes, water pump, and as we all know the radiator TVR used on Chimaeras was just a Range Rover rad with some very minor changes to the hose outlet angles. Ok so compression ratio is going to have a bearing on heat production for sure, but I've said it hundred times now so I'll say it again... "the peak coolant temperature seen by your engine (no matter which capacity it is) will always be after the thermostat (even an 88c thermostat) has fully opened".
Once this is understood you'll soon realise why you can not solve overheating issues with a lower value thermostat, FACT!
When the fans chime in on your Chimaera the coolant will be at 90c and will reach an absolute maximum of 95c before the fans help bring the coolant temp down to roughly 86c, a 5.0 litre fitted with a low value thermostat is still going to hit that absolute maximum of 95c because all the thermostats being discussed here up to and including the correct 88c one will be fully open at the 90c fan activation point.
Now we know you can't solve overheating with a lower value thermostat we need to understand all you're going to do when you fit a lower value thermostat is force the engine to take longer to warm up to it's correct 80c - 95c operating window and in the winter months run cooler than the minimum 80c out on the open road when driving at speed, however if you fit the correct 88c thermostat your engine even on a warm day will run at a consistent 86/87c which is absolutely perfect and running 86/87c is of course totally safe and exactly what the 14CUX expects to see from a fully warmed engine!
With the correct 88c thermostat fitted your ECU will be managing the fuel metering and idle behaviour precisely as it's designers intended, at this point we should not kid ourselves, it's important we all accept while some chipping of the ECU went on at TVR this only really made small changes to the fuel map. The chips used by TVR did not alter the fact the 14CUX ECU is still looking to identify a fully warmed engine condition by virtue of the coolant temperature being within the 80c - 95c window as clearly laid out in the factory fuel injection manual, this critical perimeter is embedded within the core workings of the ECU does not change one bit by fitting a fuel chip!
So if you fit a lower value thermostat you're not protecting your engine from liner slip or overheating, all you're doing is forcing the engine to take longer to reach this very important 80c - 95c coolant temp window that tells the ECU to come out of cold start enrichment and that the engine is not exceeding 95c.
What also tends to happen with an 82c thermostat is you'll see a true 80c - 83c on a warm day when driving at speed which is actually fine, however come the cooler months the coolant tends to take for ever to get there and indeed what you typically see is 75c which is well below the 80c low limit of the correct operating temp the ECU uses to determine the engine is in its fully warmed running condition.
I've run both an 82c thermostat and and the correct 88c thermostat and I can 100% guarantee you the 88c thermostat gives better results, by switching from an 82c to an 88c thermostat you'll exchange 82c for 86c when driving at speed during the summer months, this 4c difference makes absolutely fek all difference so there are no disadvantages to running an 88c thermostat... FACT!
Where the totally summer safe 88c thermostat comes into its own is when ambient temps stat to cool a little, this will typically be from the autumn months on but even during the summer if you drive your TVR at night you'll immediately start to see the benefits of switching to the correct 88c thermostat. During cooler ambient temps with an 82c thermostat you will definitely suffer sub 80c running temps at speed which puts you outside what the ECU interprets as a fully warmed engine, and for heavens sake don't fit a 74 degree thermostat what ever you do.
Even with my 88c thermostat fitted my coolant temp will fall to 81c when on the motorway on a really cold day but the engine warms up so much faster than with my old 82c thermostat and unlike the 82c thermostat coolant temps never dip below the all important 80c lower threshold.
So there are no disadvantages in fitting the correct 88c thermostat, only benefits!
TVR may well have supplied the Chimaera with an 82c thermostat but they also fitted the engine with way too cool and highly inappropriate shrouded electrode NGK B7ECS, these two choices may be perfect if you're endurance racing and probably came as a consequence of what was needed on the Tuscan Challenge cars, but the uncomfortable truth is despite the fact as TVR owners we all think we are race car driving Gods we are just not using our cars the way a Tuscan Challenge TVR got used.
The 82c thermostat and highly inappropriate way too cool shrouded electrode NGK B7ECS spark plugs used by TVR is why we so often see this....
What we are seeing here is an NGK B7ECS spark plug that being a No7 is simply not getting hot enough to self clean, we are almost certainly also seeing it the problem has compounded by the fact the coolant is not reaching the 80c - 95c window so the ECU is still applying the last stages of cold start enrichment and is a classic symptom of the too lower value thermostat syndrome.
Change the plugs to a No6, and a set of good old cheap as chips BPR6ES plugs are just fine, then replace that 82c thermostat with the correct value 88c one and all this plug fouling goes away in an instant. Your TVR will idle better, run smother out on the open road and use less fuel, finally with your new found improved combustion efficiency will come more power too.
The reality is 99.9% of us drive our TVR Chimaeras on the road 99% of the time, we are not out there campaigning in the Tuscan Challenge going balls out a wide open throttle, we are driving normally on the public highway where we will inevitably experience periods at idle and everything in between. If you are choosing components for a race car they will be very different from those that deliver optimum performance on the road, you now just need to be honest with yourself as to the genuine type of driving to actually do and admit you yourself the Rover V8 in your TVR and the 14CUX electronic fuel injection system that meters fuel to it is really 99.8% all Rage Rover/Discovery.
All this may not be what the TVR community wants to hear, but thems the facts folks!
Austin Seven said:
Very pleased with this mod, it is great to be able to trust the gauge; it was clearly not credible previously. Thanks COG for finding this one and passing it on.
Great news, gad it helped I fully expect the TVR parts specialists get hold of this one, which I think will be a good thing for the TVR community as they will buy in bulk and sell in singles.
An 88 degree thermostat works just fine, warm up is fast and it holds 85 - 88c on a run, it's also the thermostat value the engine is intended to run.
A lot of people fit an 82c thermostat (TVR included) but that doesn't make it right any more than the too cold no 7 endurance plugs TVR fitted were right, TVR seemed to be setting the engine up for the track but the truth is most drive exclusively on the road so no 6 plugs and an 88c thermostat are a far more suitable choice.
An 82c thermostat is probably preferably if you're a track day kind of guy, but you will hold around 80c on a run and often lower in winter so you'll suffer poor heater performance, but more importantly the engine management system expects a higher figure of 85 to 88c on a run.
Never fit a thermostat in the 70s as these will give very poor heater performance in the winter when you need it and the engine management system will not leave warm up enrichment, this will shorten spark plug life, kill your fuel economy and probably your kill lambda sensors too.
Enjoy, Dave.
A lot of people fit an 82c thermostat (TVR included) but that doesn't make it right any more than the too cold no 7 endurance plugs TVR fitted were right, TVR seemed to be setting the engine up for the track but the truth is most drive exclusively on the road so no 6 plugs and an 88c thermostat are a far more suitable choice.
An 82c thermostat is probably preferably if you're a track day kind of guy, but you will hold around 80c on a run and often lower in winter so you'll suffer poor heater performance, but more importantly the engine management system expects a higher figure of 85 to 88c on a run.
Never fit a thermostat in the 70s as these will give very poor heater performance in the winter when you need it and the engine management system will not leave warm up enrichment, this will shorten spark plug life, kill your fuel economy and probably your kill lambda sensors too.
Enjoy, Dave.
I hate to burst your bubble, but TVR Power who were responsible for prepping the engines they bought in from Land Rover didn't always get it right, indeed its truly laughable to think TVR knew better than the highly qualified, experienced, and well funded engineers who designed the Lucas 14CUX and developed the Rover V8 engine.
This post alone proves that TVR didn't always make the right choices or do things properly, if they had done the job properly they would have fitted a properly matched sender in a proper waterway and we wouldn't need the improved sender I've presented here and so many of us have seen great improvements from.
The truth is if you fit an 82c thermostat you may well see what you think is the right temperatures on the guage, but as proved by so many its almost certainly not your true coolant temp because temp sender accuracy is apalling due to the craaapy way TVR fitted the sender in an adapter which creates a blind spur.
Im sorry to say this is just another example of the quality of TVRs engineering standards what they did with the sender was a lazy bodge so I wouldnt blindly follow what thermostat value they specified if I were you.
The sender positioning TVR got it wrong is much like their use of inappropriately too cool and shrouded number 7 heat range spark plugs, TVR were clearly taking the lessons they learned on the track and started applying them to their road cars. This is of course a flawed approach as what works well on a race car most certainly does not work well on a road car.
If you run an 82c thermostat and the shrouded numbe 7 plugs get ready for this which is a textbook example of a spark plug failing to self clean because it's not reaching a high enough temperature to self clean.
You could follow little old TVR who built cars in a shed in Blackpool, but you'll be ignoring what the very clever engine and ECU designers/engineers at Lucas & Land Rover intended, seriously just because some blokes who worked for TVR said its right doesn't instantly mean they new better than the highly qualified engineers from Lucas and Land Rover.
History teaches us quite often the complete opposite is true in fact!
This post alone proves that TVR didn't always make the right choices or do things properly, if they had done the job properly they would have fitted a properly matched sender in a proper waterway and we wouldn't need the improved sender I've presented here and so many of us have seen great improvements from.
The truth is if you fit an 82c thermostat you may well see what you think is the right temperatures on the guage, but as proved by so many its almost certainly not your true coolant temp because temp sender accuracy is apalling due to the craaapy way TVR fitted the sender in an adapter which creates a blind spur.
Im sorry to say this is just another example of the quality of TVRs engineering standards what they did with the sender was a lazy bodge so I wouldnt blindly follow what thermostat value they specified if I were you.
The sender positioning TVR got it wrong is much like their use of inappropriately too cool and shrouded number 7 heat range spark plugs, TVR were clearly taking the lessons they learned on the track and started applying them to their road cars. This is of course a flawed approach as what works well on a race car most certainly does not work well on a road car.
If you run an 82c thermostat and the shrouded numbe 7 plugs get ready for this which is a textbook example of a spark plug failing to self clean because it's not reaching a high enough temperature to self clean.
You could follow little old TVR who built cars in a shed in Blackpool, but you'll be ignoring what the very clever engine and ECU designers/engineers at Lucas & Land Rover intended, seriously just because some blokes who worked for TVR said its right doesn't instantly mean they new better than the highly qualified engineers from Lucas and Land Rover.
History teaches us quite often the complete opposite is true in fact!
At the risk of bursting a few more bubbles for the vast majority of us what we have is just a good old low compression Range Rover engine that may or may not have had a little bit of head porting work from TVR..... but mostly not!
If you put this engine in a light sports car it may well get down the road very well indeed, but not because your old Range Rover engine has suddenly and miraculously become a highly strung, high compression, high performance exotic power plant, its still an old Range Rover engine it's just moving around a lot less mass.
TVR definitely didn't know what they were doing when they fitted the temp sender in a blind spur or we wouldn't have needed this post, and they also didn't choose well when they selected NGK B7ECS spark plugs or it wouldn't be that so many have reported benefits by switching to a BPR6ES, the exact same spark pugs specified for the old Range Rover our old Rover V8 engine was directly lifted from by the way.
For the avoidance of any doubt I'm not talking about cammed up higher compression RV8 engine builds, supercharged or turbocharged engines, I'm talking to by far the vast majority who read these pages who I recommend fit an 88c thermostat. The vast majority who just like me use a good old TVR Chimaera on the road not the race track, a road car that carries what is essentially the same good old Rover V8 that in absolutely in every important respect is exactly what you got in a good old Range Rover.
Now, if you study the engine management system the vast majority of us run which of course is the exact same engine management system used on and designed for the the good old Range Rover engine you'll discover the very clever engineers who designed it intended the engine to run within a 85-95c window, of course it's up to every owner to choose if they ignore this.
The good old Range Rover and its good old Rover V8 as fitted to the average good old TVR Chimaera used on the road which fits the profile of the vast majority of us is an engine that was designed to run BPR6ES spark plugs an an 88c thermostat, indeed the value of the thermostat is one of the critical components that not only makes up the cooling system its and equally critical component in the Lucas14CUX fuel injection system.
Of course despite the fact the highly qualified engineers at Land Rover would have conducted extensive reliability testing of the good old Rover V8 engine with an 88c thermostat in engine testing facilities that would have made the whole TVR company look like a shed at the bottom of your garden I would still never recommend an 88c thermostat to my TVR friends unless I myself had completed my own testing and seen clear benefits with absolutely no risks or downsides.
So for anyone still questioning what Land Rover specified for the good old Rover V8 and if its the right choice for your good old Chimaera that runs the same good old low compression Rover V8, I'm here to tell you I've run the 88c thermostat for some six years now and over tens of thousands of miles.
For the record my TVR does not live under a cover in the back of the workshop 90% of the year doing next to no miles every year, my TVR gets used almost every day of the week in all road conditions and all weathers. Time and time again my good old Rover V8 engine with its 88c thermostat has seen ambient temperatures soar to over 100 degrees Fahrenheit while stop start creeping along in horrific traffic jams in the South of France and Itally.
Also keep in mind my 88c thermostat equipped TVR runs on hot burning LPG that has none of the cooling effects of petrol, so if you're still not sure the engineers at Land Rover knew what they were doing when they specified an 88c thermostat for the good old Rover V8 as fitted to the vast majority of good old road driven Chimaeras don't worry, I've done six years and tens of thousand of miles of additional exhaustive and intensive stress testing of my engine fitted with an 88c thermostat and I'm hear to 100% reassure you all there are absolutely no risks whatsoever.
Now if we focus on the dreaded overheating condition for a moment of course it doesn't matter a jot if you fit a 75c, 82c or an 88c thermostat, because the fact is your peak temperature when you actually run the risk of overheating is still going to be the exact same 95c because all these example thermostat values will be fully open well below 90c, so all of them will be doing absolutely nothing to assist engine cooling at idle to save you from overheating.
Remember engines don't tend to to overheat when you're just driving about, air flow through your radiator sees to that, liquid cooled engines tend to overheat at idle which is why we tend to see this happen in traffic jams. To be clear if you fit an 82c thermostat you'll be driving about at 80-82c so the only difference when driving about on an 88c thermostat is you'll see 85-88c and both will hit the same 95 absolute peak at idle but mostly more like 93ish, if you are really worried about overheating just lower your fan on temp as this will actually do something where no thermostat even a 75c one can ever hope to help because it will be fully open long before your engine reaches peak coolant temp.
Thems the facts folks so don't be put off fitting an 88c thermostat, all its going to give you is faster warm up times, better heater performance in the cooler months when you need it, and an engine that will operate in the temperature window the designers of the fuel injection system intended.
This post is for the vast majority of good old Chimaeara owners who run their good old standard Rover V8 in their good old Chimaera on the road, track day types and the forced induction crowd should follow the more track focused spark plug and thermostat choices made by TVR. For the record TVR did get it right, its just somewhere along the way they forgot the vast majority of the cars they where building were actually going to be used on the road... not the race track!
If you put this engine in a light sports car it may well get down the road very well indeed, but not because your old Range Rover engine has suddenly and miraculously become a highly strung, high compression, high performance exotic power plant, its still an old Range Rover engine it's just moving around a lot less mass.
TVR definitely didn't know what they were doing when they fitted the temp sender in a blind spur or we wouldn't have needed this post, and they also didn't choose well when they selected NGK B7ECS spark plugs or it wouldn't be that so many have reported benefits by switching to a BPR6ES, the exact same spark pugs specified for the old Range Rover our old Rover V8 engine was directly lifted from by the way.
For the avoidance of any doubt I'm not talking about cammed up higher compression RV8 engine builds, supercharged or turbocharged engines, I'm talking to by far the vast majority who read these pages who I recommend fit an 88c thermostat. The vast majority who just like me use a good old TVR Chimaera on the road not the race track, a road car that carries what is essentially the same good old Rover V8 that in absolutely in every important respect is exactly what you got in a good old Range Rover.
Now, if you study the engine management system the vast majority of us run which of course is the exact same engine management system used on and designed for the the good old Range Rover engine you'll discover the very clever engineers who designed it intended the engine to run within a 85-95c window, of course it's up to every owner to choose if they ignore this.
The good old Range Rover and its good old Rover V8 as fitted to the average good old TVR Chimaera used on the road which fits the profile of the vast majority of us is an engine that was designed to run BPR6ES spark plugs an an 88c thermostat, indeed the value of the thermostat is one of the critical components that not only makes up the cooling system its and equally critical component in the Lucas14CUX fuel injection system.
Of course despite the fact the highly qualified engineers at Land Rover would have conducted extensive reliability testing of the good old Rover V8 engine with an 88c thermostat in engine testing facilities that would have made the whole TVR company look like a shed at the bottom of your garden I would still never recommend an 88c thermostat to my TVR friends unless I myself had completed my own testing and seen clear benefits with absolutely no risks or downsides.
So for anyone still questioning what Land Rover specified for the good old Rover V8 and if its the right choice for your good old Chimaera that runs the same good old low compression Rover V8, I'm here to tell you I've run the 88c thermostat for some six years now and over tens of thousands of miles.
For the record my TVR does not live under a cover in the back of the workshop 90% of the year doing next to no miles every year, my TVR gets used almost every day of the week in all road conditions and all weathers. Time and time again my good old Rover V8 engine with its 88c thermostat has seen ambient temperatures soar to over 100 degrees Fahrenheit while stop start creeping along in horrific traffic jams in the South of France and Itally.
Also keep in mind my 88c thermostat equipped TVR runs on hot burning LPG that has none of the cooling effects of petrol, so if you're still not sure the engineers at Land Rover knew what they were doing when they specified an 88c thermostat for the good old Rover V8 as fitted to the vast majority of good old road driven Chimaeras don't worry, I've done six years and tens of thousand of miles of additional exhaustive and intensive stress testing of my engine fitted with an 88c thermostat and I'm hear to 100% reassure you all there are absolutely no risks whatsoever.
Now if we focus on the dreaded overheating condition for a moment of course it doesn't matter a jot if you fit a 75c, 82c or an 88c thermostat, because the fact is your peak temperature when you actually run the risk of overheating is still going to be the exact same 95c because all these example thermostat values will be fully open well below 90c, so all of them will be doing absolutely nothing to assist engine cooling at idle to save you from overheating.
Remember engines don't tend to to overheat when you're just driving about, air flow through your radiator sees to that, liquid cooled engines tend to overheat at idle which is why we tend to see this happen in traffic jams. To be clear if you fit an 82c thermostat you'll be driving about at 80-82c so the only difference when driving about on an 88c thermostat is you'll see 85-88c and both will hit the same 95 absolute peak at idle but mostly more like 93ish, if you are really worried about overheating just lower your fan on temp as this will actually do something where no thermostat even a 75c one can ever hope to help because it will be fully open long before your engine reaches peak coolant temp.
Thems the facts folks so don't be put off fitting an 88c thermostat, all its going to give you is faster warm up times, better heater performance in the cooler months when you need it, and an engine that will operate in the temperature window the designers of the fuel injection system intended.
This post is for the vast majority of good old Chimaeara owners who run their good old standard Rover V8 in their good old Chimaera on the road, track day types and the forced induction crowd should follow the more track focused spark plug and thermostat choices made by TVR. For the record TVR did get it right, its just somewhere along the way they forgot the vast majority of the cars they where building were actually going to be used on the road... not the race track!
Edited by ChimpOnGas on Friday 9th August 08:05
Nice one Dalamar
I suspect when DT said they went to Smiths they're referring to Caerbont who supply the TT6811-03 sender and many products branded as Smiths.
https://www.caigauge.com/smiths-instruments
So it looks Caerbont either let DT order the TT6811-03 in singles or DT ordered two or more, in either case DT are definitely worth a call for anyone who just wants one TT6811-03 sender.
Nice work Dalamar, it looks like you've sorted it
I suspect when DT said they went to Smiths they're referring to Caerbont who supply the TT6811-03 sender and many products branded as Smiths.
https://www.caigauge.com/smiths-instruments
So it looks Caerbont either let DT order the TT6811-03 in singles or DT ordered two or more, in either case DT are definitely worth a call for anyone who just wants one TT6811-03 sender.
Nice work Dalamar, it looks like you've sorted it
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