Poll on low temperature thermostat
Poll: Poll on low temperature thermostat
Total Members Polled: 76
Discussion
Morning all
I have just had a low temprature thermostat fitted by my local independent specialist and I was wondering what the general view is on them.
Do you think they are a good idea?
Do you have one?
Are you planning on getting one?
Just curious really as my brother in law (who has a 997 C4S) was asking me whether it was worth fitting and I guess I couldn't really answer!
I know the low temp thermostat means that the coolant circulates round the engine 'earlier' than it would with a standard thermostat and that *may* mean it could reduce the chances of the cylinder changing shape but I have no proof of this and I have just taken it as read that it's a good idea to fit one......a bit like an insurance policy really.
What is the general view on them?
I have just had a low temprature thermostat fitted by my local independent specialist and I was wondering what the general view is on them.
Do you think they are a good idea?
Do you have one?
Are you planning on getting one?
Just curious really as my brother in law (who has a 997 C4S) was asking me whether it was worth fitting and I guess I couldn't really answer!
I know the low temp thermostat means that the coolant circulates round the engine 'earlier' than it would with a standard thermostat and that *may* mean it could reduce the chances of the cylinder changing shape but I have no proof of this and I have just taken it as read that it's a good idea to fit one......a bit like an insurance policy really.
What is the general view on them?
It is not rocket science. About 99% of the failures of scored bores occur on bank 2 of the engine. Scoring occurs when the temperature between the piston and the cylinder bore becomes too hot, and thins the oil viscosity too much just there and no longer prevents the friction from overheating the piston face and it melts and instantaneously solidifies again in lumps that score themselves into the cylinder bore.
Why only bank 2 and not the seemingly identical bank 1?
The pistons pushes hardest on the thrust stroke. On bank one this is on the bottom face of the cylinder bore where the coolant flows in - so is the coolest. On Bank 2 it is the top of the cylinder but the coolant still flows into the bottom so by the time it gets to the top it is a little hotter (that's its job - to take heat away from the engine by getting hotter).
That small temperature increase is just enough to make some engines score a cylinder or 2 but must therefore be a very tight marginal temperature rise between the top and bottom of each cylinder bank and therefore can be made more reliable if that small temperature difference could be catered for on bank 2.
If it was possible to lower the temperature on bank 2 so the top of the cylinders are as cool as the bottom on bank 1 - it seems logical that they would not fail as much (since everything else is identical).
Without stripping and rebuilding an engine there is nothing practical that can be done to lower the cylinder temperature on bank 2 except to lower it overall by fitting a lower temperature thermostat - so the top of bank 2 cylinders now run at the same temperature the bottom of bank 1 used to. Of course bank 1 will now run slightly cooler than before and there is no guarantee that it will always prevent scoring one day (especially if there are other problems emerging like leaky radiators, stuck fans or an old coolant pump) - but for £60.00 +Vat - frankly it is a no brainer to me.
If you fit one and it doesn't go wrong in the future you will never know if it was worth it or not (but you will not have a failed engine). If you fit one and it still goes wrong - there must have been something else wrong anway but at least you tried. If you don't fit one and your engine scores - you will have done nothing to try and prevent it and be due a huge bill to fix it.
Your choice.
Baz
Why only bank 2 and not the seemingly identical bank 1?
The pistons pushes hardest on the thrust stroke. On bank one this is on the bottom face of the cylinder bore where the coolant flows in - so is the coolest. On Bank 2 it is the top of the cylinder but the coolant still flows into the bottom so by the time it gets to the top it is a little hotter (that's its job - to take heat away from the engine by getting hotter).
That small temperature increase is just enough to make some engines score a cylinder or 2 but must therefore be a very tight marginal temperature rise between the top and bottom of each cylinder bank and therefore can be made more reliable if that small temperature difference could be catered for on bank 2.
If it was possible to lower the temperature on bank 2 so the top of the cylinders are as cool as the bottom on bank 1 - it seems logical that they would not fail as much (since everything else is identical).
Without stripping and rebuilding an engine there is nothing practical that can be done to lower the cylinder temperature on bank 2 except to lower it overall by fitting a lower temperature thermostat - so the top of bank 2 cylinders now run at the same temperature the bottom of bank 1 used to. Of course bank 1 will now run slightly cooler than before and there is no guarantee that it will always prevent scoring one day (especially if there are other problems emerging like leaky radiators, stuck fans or an old coolant pump) - but for £60.00 +Vat - frankly it is a no brainer to me.
If you fit one and it doesn't go wrong in the future you will never know if it was worth it or not (but you will not have a failed engine). If you fit one and it still goes wrong - there must have been something else wrong anway but at least you tried. If you don't fit one and your engine scores - you will have done nothing to try and prevent it and be due a huge bill to fix it.
Your choice.
Baz
hartech said:
- but for £60.00 +Vat - frankly it is a no brainer to me.
Is there a need to flush the coolant etc when replacing the thermostat with a lower temperature one (thus bumping up the cost considerably)?Also, where does one purchase these lower temp thermostats, is it a Hartech only item?
Thanks!
hartech said:
It is not rocket science. About 99% of the failures of scored bores occur on bank 2 of the engine. Scoring occurs when the temperature between the piston and the cylinder bore becomes too hot, and thins the oil viscosity too much just there and no longer prevents the friction from overheating the piston face and it melts and instantaneously solidifies again in lumps that score themselves into the cylinder bore.
Why only bank 2 and not the seemingly identical bank 1?
The pistons pushes hardest on the thrust stroke. On bank one this is on the bottom face of the cylinder bore where the coolant flows in - so is the coolest. On Bank 2 it is the top of the cylinder but the coolant still flows into the bottom so by the time it gets to the top it is a little hotter (that's its job - to take heat away from the engine by getting hotter).
That small temperature increase is just enough to make some engines score a cylinder or 2 but must therefore be a very tight marginal temperature rise between the top and bottom of each cylinder bank and therefore can be made more reliable if that small temperature difference could be catered for on bank 2.
If it was possible to lower the temperature on bank 2 so the top of the cylinders are as cool as the bottom on bank 1 - it seems logical that they would not fail as much (since everything else is identical).
Without stripping and rebuilding an engine there is nothing practical that can be done to lower the cylinder temperature on bank 2 except to lower it overall by fitting a lower temperature thermostat - so the top of bank 2 cylinders now run at the same temperature the bottom of bank 1 used to. Of course bank 1 will now run slightly cooler than before and there is no guarantee that it will always prevent scoring one day (especially if there are other problems emerging like leaky radiators, stuck fans or an old coolant pump) - but for £60.00 +Vat - frankly it is a no brainer to me.
If you fit one and it doesn't go wrong in the future you will never know if it was worth it or not (but you will not have a failed engine). If you fit one and it still goes wrong - there must have been something else wrong anway but at least you tried. If you don't fit one and your engine scores - you will have done nothing to try and prevent it and be due a huge bill to fix it.
Your choice.
Baz
So Baz - how do we go about buying them from you? Fancy kicking off a new thread with free postage perhaps? Why only bank 2 and not the seemingly identical bank 1?
The pistons pushes hardest on the thrust stroke. On bank one this is on the bottom face of the cylinder bore where the coolant flows in - so is the coolest. On Bank 2 it is the top of the cylinder but the coolant still flows into the bottom so by the time it gets to the top it is a little hotter (that's its job - to take heat away from the engine by getting hotter).
That small temperature increase is just enough to make some engines score a cylinder or 2 but must therefore be a very tight marginal temperature rise between the top and bottom of each cylinder bank and therefore can be made more reliable if that small temperature difference could be catered for on bank 2.
If it was possible to lower the temperature on bank 2 so the top of the cylinders are as cool as the bottom on bank 1 - it seems logical that they would not fail as much (since everything else is identical).
Without stripping and rebuilding an engine there is nothing practical that can be done to lower the cylinder temperature on bank 2 except to lower it overall by fitting a lower temperature thermostat - so the top of bank 2 cylinders now run at the same temperature the bottom of bank 1 used to. Of course bank 1 will now run slightly cooler than before and there is no guarantee that it will always prevent scoring one day (especially if there are other problems emerging like leaky radiators, stuck fans or an old coolant pump) - but for £60.00 +Vat - frankly it is a no brainer to me.
If you fit one and it doesn't go wrong in the future you will never know if it was worth it or not (but you will not have a failed engine). If you fit one and it still goes wrong - there must have been something else wrong anway but at least you tried. If you don't fit one and your engine scores - you will have done nothing to try and prevent it and be due a huge bill to fix it.
Your choice.
Baz
Greenslade said:
So at what temperature does everybody's car run at - mine settles at 80c, whether pootling/idling or being enthusiastic. So when you have a lower temp thermostat fitted what temp do you run at now.
Out of interest every 1 degree over 80c is 1% less HP at full throttle.
On my 997 - I've never seen the water temp needle move (once it's up to temperature), but what does move around dependent on driving "style" is the oil temperature gauge. 90-95 Degrees C is roughly normal operating and spirited use takes it over 100 Degrees C. Hard use means seeing more like 110+ Out of interest every 1 degree over 80c is 1% less HP at full throttle.
Greenslade said:
So at what temperature does everybody's car run at - mine settles at 80c, whether pootling/idling or being enthusiastic. So when you have a lower temp thermostat fitted what temp do you run at now.
Out of interest every 1 degree over 80c is 1% less HP at full throttle.
Mine was noticeably under the 80 degree mark. But as I stated earlier this was going off the temp. gauge only. Unfortunately I never got to get a more accurate reading. Out of interest every 1 degree over 80c is 1% less HP at full throttle.
My 997 C2S has had its engine rebuilt at Hartech (by previous owner) and at the time the low temp thermostat was not proven technology, so was left out even though he had done a lots of other ‘betterments’.
Since I read up on it, I felt it was a no brainer, Baz has done some pretty detailed explanations on its benefits. I think it’s a decent job though as they need the car in for a day.
Will it amount to anything? I don’t know, but I ‘like to think’ I take care of my car and that’s why it’s on the Hartech maintenance plan and goes there every 6k for a service (those lads do know their cars).
As far as differences, the oil temp gauge on the left had side of the dials reads about 5c less at any given style of driving.
Since I read up on it, I felt it was a no brainer, Baz has done some pretty detailed explanations on its benefits. I think it’s a decent job though as they need the car in for a day.
Will it amount to anything? I don’t know, but I ‘like to think’ I take care of my car and that’s why it’s on the Hartech maintenance plan and goes there every 6k for a service (those lads do know their cars).
As far as differences, the oil temp gauge on the left had side of the dials reads about 5c less at any given style of driving.
Greenslade said:
So at what temperature does everybody's car run at - mine settles at 80c, whether pootling/idling or being enthusiastic. So when you have a lower temp thermostat fitted what temp do you run at now.
Out of interest every 1 degree over 80c is 1% less HP at full throttle.
My 02 Boxster's coolant temp ranges from around 190F to a high of 226F depending upon how hot is out and how I drive the car and whether I have the A/C on or not. (With the A/C on the fans run all the time and this tends to keep the coolant temp down and keeps the temp level a bit flatter.)Out of interest every 1 degree over 80c is 1% less HP at full throttle.
I took my 02 Boxster up in the hills last summer on a mid-90's day and drove the heck out of the car in lower gears holding rpms near redline until the coolant (monitored in real time) reached 226F. Then pulled over and let the engine idle. No scoring. No overheating.
That's not the first time I've driven the car in high temps. Back in 2004 I encountered 116F ambient air temp (in southern AZ) and even then while the coolant temp climbed to 226F (and stayed there even though the radiator fans were on high) and the intake air temp reached 135F and the engine compartment fan ran non-stop even at while on the highway the engine suffered no harm. The dealer on my behalf contacted the factory and I was told the factory said as long as no warning lights came on the engine suffered not one whit from the high temp running. (With over 253K miles on this engine I think the factory was right.)
Oh, I've driven the Turbo in 119F temps a year or so ago and at highway/freeway speeds for over 200 miles with nary a problem. Had I not had the outside temp display on the dash I wouldn't haven't known how hot it was. The car was unfazed by the heat.
The Boxster's t-stat is 190F and is fully open around that temp. A lower temp t-stat I can't see helping to lower the coolant temp when the temp climbs above 190F and in the case of the high heat I mentioned above, when it climbs to 226F.
What I see helping lower some the engine's operating temperature is doing what Porsche does when it wants to provide more engine cooling, and that is to add more engine cooling. More radiator. My Boxster has 2 radiators, the Turbo has 3.
The Turbo also has better aerodynamics and under the same climatic conditions appears to run cooler.
I have a graphic that shows for lower temps engine wear increases. In a 60 hour engine test at 70F (all temps are operating temps) the wear is 0.008 inches; 120F: 0.002 inches; 155F: 0.001 inches; 180F: 0.0005 inches; and 210F: 0.0003 inches.
Fuel consumption was worse at cooler temps too. At 70F: 3.8gph; then at the same temps as above: 3.5gph, 3.2gph, 2.9gph, and 2.8gph.
Lower temp t-stat? Well, an owner can do to his car whatever he wants, but for my cars? No thanks.
Sincerely,
Rockster.
Rockster - you do not have a scoring problem with a Boxster anyway (as you would see if you read our literature on the subject).
The only engines that suffer this problem are the Cayman S, 996 3.6 and 996 3.6 and 3.8.
Most of the reasons for this are published on www.hartech.org buyers guide sections 4 and 5. Some reasons additional reasons we understand but are still testing and in consultation with some of the manufacturers involved and may publish results when we are sure of the outcome in the future. Some of it we may decide to keep to ourselves.
A Boxster temperature gauge reads fairly true up to 80 to 85 deg then under states the reading - were your readings from your dash board gauge or something else. Do you also realise that if your radiator or expansion tank or cap were leaking at the temperatures you were running at then localised boiling would take place in the cylinders. Fortunately the Boxster is the most robust of this engine range.
If you gauge reads 80 when your thermostat is set for 190 (which is 88 deg C) something is not right anyway.
The thermostat is fitted on the way into the engine - the outlet temperature is therefore higher (8 to 10 degrees usually). If you re-apply your research to those running temperatures (the cylinders being the last port of call for the coolant and therefore the hottest) the majority will confirm that a lower internal engine temperature produces the most power and reliability.
You are right that if the ambient temperature is so hot and the engine worked so hard that the basic cooling system cannot lower it below 80 deg then a lower temperature thermostat will not lower it any more - but most drivers would desist from such speed if they noticed such a high temperature anyway. It is the opening temperature combined with the rate of opening that protects engines with a lower temperature thermostat fitted for longer.
Wear rates you quote are beyond silly - if parts wear 8 thou (or 0.2mm) in 60 hours (or say 2000 miles) engines would be wrecked by about 200 miles fro new!
It seems to me therefore that your apparently authoratative statements are a mixture of inacuracies, miss information and plain silly talk and are not even relevant to a Boxster anyway.
Please now tell us why bank 2 of the engines that do suffer - fail and score bores - while bank 1 doesn't.
Baz
The only engines that suffer this problem are the Cayman S, 996 3.6 and 996 3.6 and 3.8.
Most of the reasons for this are published on www.hartech.org buyers guide sections 4 and 5. Some reasons additional reasons we understand but are still testing and in consultation with some of the manufacturers involved and may publish results when we are sure of the outcome in the future. Some of it we may decide to keep to ourselves.
A Boxster temperature gauge reads fairly true up to 80 to 85 deg then under states the reading - were your readings from your dash board gauge or something else. Do you also realise that if your radiator or expansion tank or cap were leaking at the temperatures you were running at then localised boiling would take place in the cylinders. Fortunately the Boxster is the most robust of this engine range.
If you gauge reads 80 when your thermostat is set for 190 (which is 88 deg C) something is not right anyway.
The thermostat is fitted on the way into the engine - the outlet temperature is therefore higher (8 to 10 degrees usually). If you re-apply your research to those running temperatures (the cylinders being the last port of call for the coolant and therefore the hottest) the majority will confirm that a lower internal engine temperature produces the most power and reliability.
You are right that if the ambient temperature is so hot and the engine worked so hard that the basic cooling system cannot lower it below 80 deg then a lower temperature thermostat will not lower it any more - but most drivers would desist from such speed if they noticed such a high temperature anyway. It is the opening temperature combined with the rate of opening that protects engines with a lower temperature thermostat fitted for longer.
Wear rates you quote are beyond silly - if parts wear 8 thou (or 0.2mm) in 60 hours (or say 2000 miles) engines would be wrecked by about 200 miles fro new!
It seems to me therefore that your apparently authoratative statements are a mixture of inacuracies, miss information and plain silly talk and are not even relevant to a Boxster anyway.
Please now tell us why bank 2 of the engines that do suffer - fail and score bores - while bank 1 doesn't.
Baz
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