LPG Chimaera (Follow My Conversion)
Discussion
SILICONEKID345HP said:
Thanks Dave .
Could you just answer this question ?
There are millions of vehicles out there running piggy back ECU`s ,why are most people happy with this setup even if it does not adjust timing ?
Yes you're right, there are millions of vehicles out there running piggy back ECU`s that do nothing with the ignition, but to understand why you need to understand who the target market is for these systems.Could you just answer this question ?
There are millions of vehicles out there running piggy back ECU`s ,why are most people happy with this setup even if it does not adjust timing ?
Typically it's the guy with an everyday modern production car that just wants to cut his fuel bill. If you have an OEM engine management system it won't have two maps and it'll also be hard to hack the ECU, although obviously performance chips are available for a lot of cars.
If you are going dual fuel you really need two maps, the LPG industry gets around all this by intercepting what the OEM petrol ECU is doing with the petrol injectors.
This manipulation of the petrol fueling in an attempt to get the fueling right for LPG is what the LPG piggyback is doing, but the bottom line is it's starting with & twisting the wrong information.
If you wanted the piggyback to intercept & twist the petrol ignition map too things would get very complex & the systems would become much more costly.
So LPG piggyback ECUs just work on the fueling and will typically give you a 22% drop in economy over petrol, which given the significantly lower price of LPG at the pumps still delivers a huge saving.
Given the target market LPG systems need to be easy to fit, the LPG piggyback ECU needs to be easy to set up and the whole setup needs to be cheap to buy.
If they deliver the customer's expected fuel savings without messing with the ignition it makes no sense to add complexity and cost, but that doesn't mean an LPG conversion can't be a lot more efficient.
If you have a system that allows you to build bespoke fuel & ignition maps for each fuel you'll reap the rewards.
That's why my economy drop over petrol is 18% and your average LPG conversion will deliver 22%, that improvement is mostly down to the ability the Canems Duel Fuel ECU gives me to build a proper LPG ignition map.
This is because LPG is 110 Ron (petrol 95-98 Ron), it's also because LPG burns in a very different way to petrol, get the ignition map right for gas and you recover a chuck of economy loss.
Add in the ability to build a bespoke LPG fuel map and you claw back even more
You could come close to the same thing with your Emerald, you just need the LPG piggyback ECU for its peak & hold injector drivers
ChimpOnGas said:
SILICONEKID345HP said:
Thanks Dave .
Could you just answer this question ?
There are millions of vehicles out there running piggy back ECU`s ,why are most people happy with this setup even if it does not adjust timing ?
Yes you're right, there are millions of vehicles out there running piggy back ECU`s that do nothing with the ignition, but to understand why you need to understand who the target market is for these systems.Could you just answer this question ?
There are millions of vehicles out there running piggy back ECU`s ,why are most people happy with this setup even if it does not adjust timing ?
Typically it's the guy with an everyday modern production car that just wants to cut his fuel bill. If you have an OEM engine management system it won't have two maps and it'll also be hard to hack the ECU, although obviously performance chips are available for a lot of cars.
If you are going dual fuel you really need two maps, the LPG industry gets around all this by intercepting what the OEM petrol ECU is doing with the petrol injectors.
This manipulation of the petrol fueling in an attempt to get the fueling right for LPG is what the LPG piggyback is doing, but the bottom line is it's starting with & twisting the wrong information.
If you wanted the piggyback to intercept & twist the petrol ignition map too things would get very complex & the systems would become much more costly.
So LPG piggyback ECUs just work on the fueling and will typically give you a 22% drop in economy over petrol, which given the significantly lower price of LPG at the pumps still delivers a huge saving.
Given the target market LPG systems need to be easy to fit, the LPG piggyback ECU needs to be easy to set up and the whole setup needs to be cheap to buy.
If they deliver the customer's expected fuel savings without messing with the ignition it makes no sense to add complexity and cost, but that doesn't mean an LPG conversion can't be a lot more efficient.
If you have a system that allows you to build bespoke fuel & ignition maps for each fuel you'll reap the rewards.
That's why my economy drop over petrol is 18% and your average LPG conversion will deliver 22%, that improvement is mostly down to the ability the Canems Duel Fuel ECU gives me to build a proper LPG ignition map.
This is because LPG is 110 Ron (petrol 95-98 Ron), it's also because LPG burns in a very different way to petrol, get the ignition map right for gas and you recover a chuck of economy loss.
Add in the ability to build a bespoke LPG fuel map and you claw back even more
You could come close to the same thing with your Emerald, you just need the LPG piggyback ECU for its peak & hold injector drivers
ChimpOnGas said:
Yes you're right, there are millions of vehicles out there running piggy back ECU`s that do nothing with the ignition, but to understand why you need to understand who the target market is for these systems.
Typically it's the guy with an everyday modern production car that just wants to cut his fuel bill. If you have an OEM engine management system it won't have two maps and it'll also be hard to hack the ECU, although obviously performance chips are available for a lot of cars.
If you are going dual fuel you really need two maps, the LPG industry gets around all this by intercepting what the OEM petrol ECU is doing with the petrol injectors.
This manipulation of the petrol fueling in an attempt to get the fueling right for LPG is what the LPG piggyback is doing, but the bottom line is it's starting with & twisting the wrong information.
If you wanted the piggyback to intercept & twist the petrol ignition map too things would get very complex & the systems would become much more costly.
So LPG piggyback ECUs just work on the fueling and will typically give you a 22% drop in economy over petrol, which given the significantly lower price of LPG at the pumps still delivers a huge saving.
Given the target market LPG systems need to be easy to fit, the LPG piggyback ECU needs to be easy to set up and the whole setup needs to be cheap to buy.
If they deliver the customer's expected fuel savings without messing with the ignition it makes no sense to add complexity and cost, but that doesn't mean an LPG conversion can't be a lot more efficient.
If you have a system that allows you to build bespoke fuel & ignition maps for each fuel you'll reap the rewards.
That's why my economy drop over petrol is 18% and your average LPG conversion will deliver 22%, that improvement is mostly down to the ability the Canems Duel Fuel ECU gives me to build a proper LPG ignition map.
This is because LPG is 110 Ron (petrol 95-98 Ron), it's also because LPG burns in a very different way to petrol, get the ignition map right for gas and you recover a chuck of economy loss.
Add in the ability to build a bespoke LPG fuel map and you claw back even more
You could come close to the same thing with your Emerald, you just need the LPG piggyback ECU for its peak & hold injector drivers
That`s brilliant ,so basiclly the piston is not in the right place when it sparks . That`s probably why in the old days it was very difficult to get the engine running well on both fuels when running a distributor.Typically it's the guy with an everyday modern production car that just wants to cut his fuel bill. If you have an OEM engine management system it won't have two maps and it'll also be hard to hack the ECU, although obviously performance chips are available for a lot of cars.
If you are going dual fuel you really need two maps, the LPG industry gets around all this by intercepting what the OEM petrol ECU is doing with the petrol injectors.
This manipulation of the petrol fueling in an attempt to get the fueling right for LPG is what the LPG piggyback is doing, but the bottom line is it's starting with & twisting the wrong information.
If you wanted the piggyback to intercept & twist the petrol ignition map too things would get very complex & the systems would become much more costly.
So LPG piggyback ECUs just work on the fueling and will typically give you a 22% drop in economy over petrol, which given the significantly lower price of LPG at the pumps still delivers a huge saving.
Given the target market LPG systems need to be easy to fit, the LPG piggyback ECU needs to be easy to set up and the whole setup needs to be cheap to buy.
If they deliver the customer's expected fuel savings without messing with the ignition it makes no sense to add complexity and cost, but that doesn't mean an LPG conversion can't be a lot more efficient.
If you have a system that allows you to build bespoke fuel & ignition maps for each fuel you'll reap the rewards.
That's why my economy drop over petrol is 18% and your average LPG conversion will deliver 22%, that improvement is mostly down to the ability the Canems Duel Fuel ECU gives me to build a proper LPG ignition map.
This is because LPG is 110 Ron (petrol 95-98 Ron), it's also because LPG burns in a very different way to petrol, get the ignition map right for gas and you recover a chuck of economy loss.
Add in the ability to build a bespoke LPG fuel map and you claw back even more
You could come close to the same thing with your Emerald, you just need the LPG piggyback ECU for its peak & hold injector drivers
When setup for LPG the engine would pink when running on Petrol .
ss ,we need knowledgeable blokes like Dave who has the balls to take massive projects like this .
CHIMV8 said:
I read shorter novels while soaking the sun in,than some of your replys LOL!
Ha ha, you boys kill me
Sardonicus said:
Boom! Boom! 
And now we've got Basil Brush chiming in
In response, I'll make three simple points...
1. My posts may be long, but clearly you're still reading them, or you wouldn't be commenting
2. Even though I sometimes struggle to be concise I do try to keep what I'm saying accurate, informative & based on everything I've genuinely learned & continue to learn on my demented LPG TVR journey
3. Invariably there are more people quietly & anonymously reading all my waffle, enjoying & never commenting on it..... than reading & complaining about how long my posts are
Read if you're interested, ignore if you're not; but I can't see the point in reading it all then complaining its too long & detailed
Love you all (especially Daz)
wuckfitracing said:
As a fan of your posts and a fellow LPG runner (not on the Chim though) keep em coming. Superb.
Thanks Colin & Simon, and that's enough encouragement for me to go into waffle mode again, as we know I don't need much encouragement The next development of 'Ol Gasbag' being an LPG volume correction strategy that will provide pre-combustion correction to compliment the post combustion closed loop correction.
The volume of LPG changes considerably more than a liquid fuel over the range of normal ambient & under bonnet temps, as the volume changes so does the air fuel ratio unless you have some form of correction strategy.
As such an open loop map doesn't work that well, only the automatic ECU correction provided by referencing a wide band lambda sensor is fast enough to nail AFRs over a range of normal operating temps.
But even closed loop isn't perfect as its an after combustion event correction strategy, what the ECU is working with on closed loop is what went on the last time fuel was burnt by analyzing the waste product. It then makes changes based of the assumption everything with the fueling is going to be the same for the upcoming next combustion event, in effect the ECU is already working with old redundant data.
And the reality is the volume swings on LPG can be so violent & rapid this assumption is rather flawed. Of course closed loop correction is happening so rapidly over thousands of combustion events what you tend to see on the AFR meter is a blending average effect around your targets.
But to be honest my AFRs on gas still aren't quite as constant as they are on petrol with a +- 0.5 (or more) swing around the target being commonly observed on my AEM X-Wifi wireless IPod Touch AFR reader.
So what about if you look at, understand & correct for the volume of the fuel before it even reaches the injectors?
That to me is worth exploring, so very soon with the help of David Hampshire at Canems I'll be correcting the LPG injector durations before the combustion event based on the true volume of the LPG just before it enters the combustion chamber, which should give the ECU an easier life than simply relying the current closed loop strategy (which will of course still remain in place).
Get the fueling right before combustion, then fine tweak things using the post combustion closed loop strategy and I'm hoping we can hit the magic 15% increase in fuel consumption over petrol which remains the holy grail of LPG vapor injection.
I'm currently running semi-sequential batch fired injection, any further improvements after we've got LPG volume correction working properly will only come from implementing fully sequential injection.
But for fully sequential injection I'll need a cam position sensor and that's where the ancient engine I'm working with really starts to let me down.
But hey......never say never
Edited by ChimpOnGas on Sunday 18th January 11:47
ChimpOnGas said:
Thanks Colin & Simon, and that's enough encouragement for me to go into waffle mode again, as we know I don't need much encouragement
The next development of 'Ol Gasbag' being an LPG volume correction strategy that will provide pre-combustion correction to compliment the post combustion closed loop correction.
The volume of LPG changes considerably more than a liquid fuel over the range of normal ambient & under bonnet temps, as the volume changes so does the air fuel ratio unless you have some form of correction strategy.
As such an open loop map doesn't work that well, only the automatic ECU correction provided by referencing a wide band lambda sensor is fast enough to nail AFRs over a range of normal operating temps.
But even closed loop isn't perfect as its an after combustion event correction strategy, what the ECU is working with on closed loop is what went on the last time fuel was burnt by analyzing the waste product. It then makes changes based of the assumption everything with the fueling is going to be the same for the upcoming next combustion event, in effect the ECU is already working with old redundant data.
And the reality is the volume swings on LPG can be so violent & rapid this assumption is rather flawed. Of course closed loop correction is happening so rapidly over thousands of combustion events what you tend to see on the AFR meter is a blending average effect around your targets.
But to be honest my AFRs on gas still aren't quite as constant as they are on petrol with a +- 0.5 (or more) swing around the target being commonly observed on my AEM X-Wifi wireless IPod Touch AFR reader.
So what about if you look at, understand & correct for the volume of the fuel before it even reaches the injectors?
That to me is worth exploring, so very soon with the help of David Hampshire at Canems I'll be correcting the LPG injector durations before the combustion event based on the true volume of the LPG just before it enters the combustion chamber, which should give the ECU an easier life than simply relying the current closed loop strategy (which will of course still remain in place).
Get the fueling right before combustion, then fine tweak things using the post combustion closed loop strategy and I'm hoping we can hit the magic 15% increase in fuel consumption over petrol which remains the holy grail of LPG vapor injection.
I'm currently running semi-sequential batch fired injection, any further improvements after we've got LPG volume correction working properly will only come from implementing fully sequential injection.
But for fully sequential injection I'll need a cam position sensor and that's where the ancient engine I'm working with really starts to let me down.
But hey......never say never
My advice would be to have a LPG tank berried in your garden and purchase pump ,even more savings .The next development of 'Ol Gasbag' being an LPG volume correction strategy that will provide pre-combustion correction to compliment the post combustion closed loop correction.
The volume of LPG changes considerably more than a liquid fuel over the range of normal ambient & under bonnet temps, as the volume changes so does the air fuel ratio unless you have some form of correction strategy.
As such an open loop map doesn't work that well, only the automatic ECU correction provided by referencing a wide band lambda sensor is fast enough to nail AFRs over a range of normal operating temps.
But even closed loop isn't perfect as its an after combustion event correction strategy, what the ECU is working with on closed loop is what went on the last time fuel was burnt by analyzing the waste product. It then makes changes based of the assumption everything with the fueling is going to be the same for the upcoming next combustion event, in effect the ECU is already working with old redundant data.
And the reality is the volume swings on LPG can be so violent & rapid this assumption is rather flawed. Of course closed loop correction is happening so rapidly over thousands of combustion events what you tend to see on the AFR meter is a blending average effect around your targets.
But to be honest my AFRs on gas still aren't quite as constant as they are on petrol with a +- 0.5 (or more) swing around the target being commonly observed on my AEM X-Wifi wireless IPod Touch AFR reader.
So what about if you look at, understand & correct for the volume of the fuel before it even reaches the injectors?
That to me is worth exploring, so very soon with the help of David Hampshire at Canems I'll be correcting the LPG injector durations before the combustion event based on the true volume of the LPG just before it enters the combustion chamber, which should give the ECU an easier life than simply relying the current closed loop strategy (which will of course still remain in place).
Get the fueling right before combustion, then fine tweak things using the post combustion closed loop strategy and I'm hoping we can hit the magic 15% increase in fuel consumption over petrol which remains the holy grail of LPG vapor injection.
I'm currently running semi-sequential batch fired injection, any further improvements after we've got LPG volume correction working properly will only come from implementing fully sequential injection.
But for fully sequential injection I'll need a cam position sensor and that's where the ancient engine I'm working with really starts to let me down.
But hey......never say never
Edited by ChimpOnGas on Sunday 18th January 11:47
It is the same stuff isn`t it !
Sardonicus said:
Cam phasing is easy even with the RV8 Dave using the stock dizzy but modified (making it stumpy if you like) you only need one trigger event every engine cycle the ECU sorts the injection timing etc 
Super interested in this & need to learn more Simon, teach me please.Edited by Sardonicus on Sunday 18th January 18:51
Speak to your ECU installers 1st Dave but providing your inj loom had each ground returned back to the ECU rather than wired for batch fire within the loom i.e like the stock CUX loom (or it will be another loom)other than that its just a matter of a bit of extra wiring to the cam sensor and setting up within the software providing the Canems has the additional outputs of 8 inj grounds rather than your current four (semi seq) obviously there will be a bit of trial and error and optimization but you get the jist and using something like this 
Its been done before 
Its been done before Edited by Sardonicus on Sunday 18th January 21:13
Sardonicus said:
Speak to your ECU installers 1st Dave but providing your inj loom had each ground returned back to the ECU rather than wired for batch fire within the loom i.e like the stock CUX loom (or it will be another loom)other than that its just a matter of a bit of extra wiring to the cam sensor and setting up within the software providing the Canems has the additional outputs of 8 inj grounds rather than your current four (semi seq) obviously there will be a bit of trial and error and optimization but you get the jist and using something like this
Point two in the detail specification below looks interesting?
[url]
|http://thumbsnap.com/d5zuoHab[/url
ChimpOnGas said:
On a separate note here's one especially for Daz...
Photo taken this afternoon, when was the last time you paid £2.49 for a gallon of fuel?
Stop press, LPG now being sold at the above station for £0.489p a litre.Photo taken this afternoon, when was the last time you paid £2.49 for a gallon of fuel?
That's just £2.22 a gallon!!!
I did 204 miles yesterday for £19.70, so it's now delivering better economy than the Holy Grail £0.10p a mile.
You'll need to be getting 48mpg from your petrol car to match that, not bad for a 4.0 litre V8 TVR
New gas volume correction strategy and vaporiser temp management system to follow in a week or so to deliver even better economy figures.
'Ol Gasbag' just gets better and better
SILICONEKID345HP said:
Otherwise known as single point or a gas ring.Utter shyte!!!
Makes a carburetor look like a state of the art fuel delivery/metering device.
Avoid!!!!
If you know what you're doing though, gas is good
https://www.youtube.com/watch?v=YF8G318wHt0#t=19
A turbo 4.0-litre delivering a 9 second pass on regular forecourt LPG.
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