LPG Chimaera (Follow My Conversion)

[ChimpOnGas]

SILICONEKID345HP said:

I`m happy with a standard tank bolted down in the back, now i am even more confused .I thought the piggyback read fueling and spark then made calculations to convert to LPG .

I have three maps 1 Full power 2 full power with pops and bangs and 3 a slightly leaned out map .

I thought i could have another switch to switch over to LPG then let the LPG copy which ever map i choose.

Did i get that completely wrong ?. .. It does sound good .

Well I'm not sure I can make it any clearer, just re-read my post slowly but this time try and digest the information.

If you want to keep the standard petrol tank go for it, just be aware that will mean your LPG tank will end up strapped to the paper thin fibreglass boot floor. This in turn will mean if you ever get rear ended the super strong steel LPG tank wiIl be forced into the aluminium petrol tank splitting it open and spilling petrol all over the LPG tank which has a nice 12v solenoid on it to get things really going

If you're happy with that fine, personally it's not for me.

You already have an excellent Emerald ECU with more than one map, so you've already got a good head start. Just fit an AEM Peak & Hold driver pack or better still an 8 cylinder LPG piggyback ECU and follow the rest of the instructions above.

If you don't like the 40-50mpg average economy with no performance loss you can easily go back to the original petrol only set up and no one would ever know.

Less than £1000 in parts plus fitting and a bit of fabrication work should do it, say £1500 in total.

[SILICONEKID345HP]

ChimpOnGas said:

Well I'm not sure I can make it any clearer, just re-read my post slowly but this time try and digest the information.

If you want to keep the standard petrol tank go for it, just be aware that will mean your LPG tank will end up strapped to the paper thin fibreglass boot floor. This in turn will mean if you ever get rear ended the super strong steel LPG tank wiIl be forced into the aluminium petrol tank splitting it open and spilling petrol all over the LPG tank which has a nice 12v solenoid on it to get things really going

If you're happy with that fine, personally it's not for me.

You already have an excellent Emerald ECU with more than one map, so you've already got a good head start. Just fit an AEM Peak & Hold driver pack or better still an 8 cylinder LPG piggyback ECU and follow the rest of the instructions above.

If you don't like the 40-50mpg average economy with no performance loss you can easily go back to the original petrol only set up and no one would ever know.

Less than £1000 in parts plus fitting and a bit of fabrication work should do it, say £1500 in total.

Thanks Dave . I could start by buying the bits once i find exactly what i need . Most of these LPG installers would not have a clue to do it the way you explained .I don`t fancy having the wasted spark kept the same ,it would be a waste of time .

Edited by SILICONEKID345HP on Sunday 21st December 22:08

[v8mgbgt]

Hi. I'm building a 700 hp ish jaguar XKR using the Ls9 supercharged engine.
Since my car is from a new shell I want to complete its initial registration on lpg only, which will reduce it's tax band.
If that works fine I'm happy to stay on gas only. This is not a daily use car so will be warming it up properly be using it.

I believe the Canem dual fuel ECU is my best option and intend to use Lloyds.

Most high spec injectors seem to supporti around 50hp I suppose I would need 16 to give me 800 hp capacity if I want even distribution. Unless you know of any injectors capable of supporting 90 hp.

Any recommendations on evaporaters and injector combinations to complete this setup would be appreciated.

Thanks

Nick

Edited by v8mgbgt on Saturday 3rd January 10:39

Edited by v8mgbgt on Sunday 4th January 09:56

[Boosted LS1]

Great thread.

I wanted to use lpg many years ago but back then I was kept waiting for dual fuel injectors to arrive. They never did, so the project was shelved. I also considered running 8 lpg injectors into the inlet ports of an aftermarket manifold with a holley carb sitting on top for when I wanted to use petrol. I was using a 'blow through TT' at the time.

It's good to see that things have moved on. I still plan to use lpg.

[ChimpOnGas]

v8mgbgt said:

Hi. I'm building a 700 hp ish jaguar XKR using the Ls9 supercharged engine.
Since my car is from a new shell I want to complete its initial registration on lpg only, which will reduce it's tax band.
If that works fine I'm happy to stay on gas only. This is not a daily use car so will be warming it up properly be using it.

I believe the Canem dual fuel ECU is my best option and intend to use Lloyds.

Most high spec injectors seem to supporti around 50hp I suppose I would need 16 to give me 800 hp capacity if I want even distribution. Unless you know of any injectors capable of supporting 90 hp.

Any recommendations on evaporaters and injector combinations to complete this setup would be appreciated.

Thanks

Nick

wow, that's some project!

For the vaporizer use two of these:

http://www.lpgshop.co.uk/kme-twin-410hp-reducer-in...

Your challenge will be the injectors, to get the capacity you need yet maintain resolution at low RPM to ensure good driveability you will almost certainly need staged injection (16 injectors - 8 up to 3k RPM and the second set of 8 joining in after that).

David Hampshire of Canems wound need to build a bespoke ECU perhaps based on the LS system he supplies to Garner Douglas?

It seems you're already talking to Lloyd Specialist Developments who work hang in glove with Canems and are true engineers that approach such projects with an with a engineer's approach to problem solving.

If I were you Id also be looking to contact the Australian drag racing community for advice on big horse power LPG systems, there are many guys down under that are making massive figures on gas so there's definitely something to be learned from them.

I'm not sure I'd go LPG only as the tax benefits are negligible and the cold start issues you'll be force to overcome will be quite challenging.

Have you considered going liquid injection?

Doing so would solve the injector sizing issue in a stroke as you'll no longer need peak & hold LPG injectors, as the name suggests with liquid injection you inject LPG still in it's liquid state through your existing petrol injectors.

Liquid injection requires a special LPG tank that houses a high pressure pump to keep the LPG in its compressed liquefied state right up to the injectors, once you've overcome the tank and pump challenges the fuel management through an decent ECU should be relatively straightforward.

Liquid injection also solves the cold start issue inherent in gaseous systems and the super cooled liquefied LPG is perfect for removing the heat created by a supercharger.

If I were you I'd definitely start some deep research into liquid injection, look again to Australia and Italy where these systems have been used for some years. Also Google Rouch LPG Mustang, Rouch USA are running an 800hp blown Mustang on a liquid propane system with amazing results.

http://www.muscularmustangs.com/2009/news0274_rous...

Good luck with your project, Dave.

Edited by ChimpOnGas on Friday 2nd January 11:58

[v8mgbgt]

Thanks Dave that is really helpful.

Because my car is a new build If I register on petrol the first years tax will be around £1,100 then £550 thereafter.
On LPG it will whichever low tax band I can get the immissions down to on the day of the test.. Maybe not zero with factory cats and eco tune, but definitely a lot less

There seems little point in putting it on the road if I can't afford to run it, so LPG solves both economy and road tax issue.

Liquid injection sounds like the way to go. I presume you need very high pressure injectors. I would think normal petrol injectors top out after 80 psi. LPG I read can stored upto 300psi.

Seems a shame to watste all that cooling on the evaporaters when it can cool combustion.

Will do some research on that.

Cheers

Nick

Edited by v8mgbgt on Friday 2nd January 16:14

Edited by v8mgbgt on Friday 2nd January 18:04

[ChimpOnGas]

v8mgbgt said:

Thanks Dave that is really helpful.

Because my car is a new build If I register on petrol the first years tax will be around £1,100 then £550 thereafter.
On LPG it will whichever low tax band I can get the immissions down to on the day of the test.. Maybe not zero with factory cats and eco tune, but definitely a lot less

There seems little point in putting it on the road if I can't afford to run it, so LPG solves both economy and road tax issue.

Liquid injection sounds like the way to go. I presume you need very high pressure injectors. I would think normal petrol injectors top out after 80 psi. LPG I read can stored upto 300psi.

Seems a shame to watste all that cooling on the evaporaters when it can cool combustion.

Will do some research on that.

Cheers

Nick

Edited by v8mgbgt on Friday 2nd January 16:14

Edited by v8mgbgt on Friday 2nd January 18:04

Wonderful project, very interesting, very well considered, very innovative.

The tax benefit makes perfect sense now you've explained it, very well conceived indeed.

In theory there are many benefits in injecting propane while its still in its compressed liquid state and many advantages over a gaseous such as mine, given your objectives I would say it represents the perfect solution.

However, you do face some significant challenges, the two key reasons liquid LPG systems haven't taken off yet are.

1. The high pressure pump must be fitted inside the LPG tank

This means you'll need to commission a specific tank for your application and is why the few liquid LPG kits offered are typically vehicle specific.

2. The reliability of high pressure tank mounted LPG pumps is poor

This is because the pump must work extremely hard while submerged in liquid propane within the tank and that's a very punishing environment indeed.

But don't let this put you off, if you can overcome these two challenges the benefits of liquid over gaseous LPG are immense. I've already proved you can make more power on gas than petrol injecting it as a gas, if you can reliably inject it as a liquid you're in for even bigger gains.

When you buy LPG at the pump you are not only getting the fuel, you're getting the energy used to compress it at the refinery, I currently throw this energy away when I turn the fuel back from liquid to gas in my engine coolant heated vaporizer. This wasteful approach is nothing short of criminal when I should be using the super cooling energy to further improve cylinder filling & volumetric efficiency.

The truth is it's very hard (probably impossible) to access this free energy with a gaseous system, but with a liquid system it's there to be enjoyed.

In summery you would be mad not to go liquid, focus on solving the two challenges above and you're results could very well be outstanding!

Bon chance!

Edited by ChimpOnGas on Friday 2nd January 19:11

[Boosted LS1]

The company I spoke with for liquid injection was based in Melbourne. I'll try to find the name when I get a chance. They seemed to provide installs for taxi firms in New York and were state approved or something like that. It has all the obvious benefits, especially for forced induction but as I mentioned earlier, dual fuel injectors hadn't come on stream. Does anybody know if these are a possibility? I guess they're probably not so important these days.

Dave, are you certain the pump has to be mounted inside the tank?

Edited by Boosted LS1 on Friday 2nd January 20:42

[SILICONEKID345HP]

Have you thought about cryogenic LNG (running in Taxis and buses) or even Hydrogen-Oxygen Fuel Cell ? Just fill up with water and go

Gasification might be the way to go https://www.youtube.com/watch?v=Zn2DYzgWB00

Edited by SILICONEKID345HP on Friday 2nd January 20:49

[v8mgbgt]

Thanks for your replys. Seem to be hijacking Chimp,s thread so I will start a new thread on Liqued LPG

Edited by v8mgbgt on Sunday 4th January 10:50

[ChimpOnGas]

v8mgbgt said:

Thanks for your replys. Seem to be hijacking Chimp,s thread so I will start a new thread on Liqued LPG

Edited by v8mgbgt on Sunday 4th January 10:50

Absolutely no problem with the hijack, liquid injection is the next evolution in the world of LPG so perfectly logical for the post to evolve in this direction.

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?

On a run I'm getting 25mpg on gas, so that's the magic £0.10p a mile

Now lets look at how the cost ratio between petrol & LPG has evolved in the last few months:

October 2014: Petrol @ 1.24 per litre / LPG @ 0.68 per litre = 1.823 x 23.2mpg = a petrol cost equivalent of 42.3mpg

January 2015: Petrol @ 1.057 per litre / LPG @ 0.547 per litre = 1.932 x 23.2mpg = a petrol cost equivalent of 44.83mpg

The most important thing is not how cheaply you can buy LPG but how much cheaper it is than the petrol sold at the same station you're buying your gas from on the same day, it's the percentage difference between the two fuels that really counts.

So while its true petrol is getting a lot cheaper, LPG is actually getting even cheaper still, in the above example I've seen the cost equivalent of a 2.5mpg improvement by doing absolutely nothing

And you'll need a need a really really dull car to even come close to the average 44.83mpg economy I'm getting from my 250hp TVR

Talk about cheap thrills

[SILICONEKID345HP]

ChimpOnGas said:

Absolutely no problem with the hijack, liquid injection is the next evolution in the world of LPG so perfectly logical for the post to evolve in this direction.

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?

On a run I'm getting 25mpg on gas, so that's the magic £0.10p a mile

Now lets look at how the cost ratio between petrol & LPG has evolved in the last few months:

October 2014: Petrol @ 1.24 per litre / LPG @ 0.68 per litre = 1.823 x 23.2mpg = a petrol cost equivalent of 42.3mpg

January 2015: Petrol @ 1.057 per litre / LPG @ 0.547 per litre = 1.932 x 23.2mpg = a petrol cost equivalent of 44.83mpg

The most important thing is not how cheaply you can buy LPG but how much cheaper it is than the petrol sold at the same station you're buying your gas from on the same day, it's the percentage difference between the two fuels that really counts.

So while its true petrol is getting a lot cheaper, LPG is actually getting even cheaper still, in the above example I've seen the cost equivalent of a 2.5mpg improvement by doing absolutely nothing

And you'll need a need a really really dull car to even come close to the average 44.83mpg economy I'm getting from my 250hp TVR

Talk about cheap thrills

You are doing very well at 25mpg on LPG ,I thought you lost about a third in efficiency.

[ChimpOnGas]

SILICONEKID345HP said:

You are doing very well at 25mpg on LPG ,I thought you lost about a third in efficiency.

A third is 33.3% Daz, that may have been true for the old single point systems but these days things are much better.

Most honest LPG installers will quote you a 20% increase in fuel consumption, but if you talk to people with a converted car you will often hear the real world figures are more like 20-25% if the system is working perfectly.

In 2004 Vauxhall offered a dual fuel Astra 1.6, as you can imagine Vauxhall had access to some very skilled engineers and conducted all their testing at Millbrook so things were measured properly. Vauxhall achieved an accurately measured economy loss of 22.45% on their extensively developed production ready car, so while this all happened 10 or so years ago we should still see 22.45% as a realistic figure for a good gaseous conversion these days.

To be fair my 25mpg is the very best "Driving Miss Daisy" LPG economy figure I've seen, and that's not the normal way the car gets driven (or should be driven).

As on petrol the car's the average fuel consumption (over a meaningful period) on LPG depends on the proportion of motorway & town driving I do, mostly I seem consume LPG at 23.2mpg at 80-85mph cruise but this can easily fall to closer to 20mpg if I press on or increase the number of aggressive acceleration events.

To get to the bottom of why we need to burn more LPG than petrol we need to understand that LPG is less dense than petrol, 1 litre of LPG weighs a feeble 0.67 Kg whereas 1 litre of Petrol weighs in at 0.72 Kg.

However if really you want an efficient fuel you need Diesel, a litre of which weighs 0.832 Kg, that increased fuel density and the high compression ratios used is why Diesels are so economical.

For some time now I've been closely monitoring the percentage LPG fuel consumption increase the Canems dual fuel system is delivering with its bespoke fuel & ignition maps.

Here are the results:
|

Type Of Driving	Petrol MPG	LPG MPG	Loss %
Town	21.10	19.37	8.2%
80-85mph Motorway	28.21	23.2	17.7%

I have to say I'm extremely happy with these figures, like I say most LPG conversions never do better than 20% and most consume 25% more fuel so 17.7% at a steady 80-85mph is an excellent result, drive it in town and you're hardly seeing a direct economy drop at all.

As a less dense gaseous fuel LPG occupies a greater volume than a liquid fuel so it tends to displace more of the air in the available space within the combustion chamber. In simple terms LPG takes up more space to give the same amount of energy as a liquid fuel.

To compensate you naturally open the throttle more to let more air in, the additional throttle opening over what you would normally use on petrol increases directly in proportion to the amount of work you're asking of the engine and the percentage economy loss follows in direct proportion.

Interestingly the other way to compensate is to compress the air, not only are you effectively increasing the compression ratio and so the volumetric efficiency of the engine, you are also making the air more dense so there's more room for that air displacing LPG.

Yet more reasons why LPG & forced induction make such happy bedfellows

If I'm honest what I've found so far surprised me, on petrol the difference between driving in town & driving on the motorway is a 35% improvement, however on LPG the improvement between town & motorway is a much smaller gain of 20%. Being an air displacing volume thing it'll be the same for any LPG conversion, but not many will achieve a 17.7% loss at 80-85mph.

While all this is interesting (to me), what really matters is the 40-45mpg cost equivalent I'm regularly enjoying with no loss in performance. Anyone claiming they're getting much better than this from their LPG TVR is either buying their LPG at a crazy low price where the petrol is very expensive, or they're getting a little confused with how to work out their cost equivalent figure properly.

Edited by ChimpOnGas on Monday 12th January 00:26

[SILICONEKID345HP]

ChimpOnGas said:

A third is 33.3% Daz, that may have been true for the old single point systems but these days things are much better.

Most honest LPG installers will quote your a 20% increase in fuel consumption, but if you talk to people with a converted car you will often hear the real world figures are more like 20-25% if the system is working perfectly.

In 2004 Vauxhall offered a dual fuel Astra 1.6, as you can imagine Vauxhall had access to some very skilled engineers and conducted all their testing at Millbrook so things were measured properly. Vauxhall achieved an accurately measured economy loss of 22.45% on their extensively developed production ready car, so while this all happened 10 or so years ago we should still see 22.45% as a realistic figure for a good gaseous conversion these days.

To be fair my 25mpg is the very best "Driving Miss Daisy" LPG economy figure I've seen, and that's not the normal way the car gets driven (or should be driven).

As on petrol the car's the average fuel consumption (over a meaningful period) on LPG depends on the proportion of motorway & town driving I do, mostly I seem consume LPG at 23.2mpg at 80-85mph cruise but this can easily fall to closer to 20mpg if I press on or increase the number of aggressive acceleration events.

To get to the bottom of why we need to burn more LPG than petrol we need to understand that LPG is less dense than petrol, 1 litre of LPG weighs a feeble 0.67 Kg whereas 1 litre of Petrol weighs in at 0.72 Kg.

However if really you want an efficient fuel you need Diesel, a lite of which weighs 0.832 Kg, that increased fuel density and the high compression ratios used is why Diesels are so economical.

For some time now I've been closely monitoring the percentage LPG fuel consumption increase the Canems dual fuel system is delivering with its bespoke fuel & ignition maps.

Here are the results:
|

Type Of Driving	Petrol MPG	LPG MPG	Loss %
Town	21.10	19.37	8.2%
80-85mph Motorway	28.21	23.2	17.7%

I have to say I'm extremely happy with these figures, like I say most LPG conversions never do better than 20% and most consume 25% more fuel so 17.7% at a steady 80-85mph is an excellent result, drive it in town and you're hardly seeing a direct economy drop at all.

As a less dense gaseous fuel LPG occupies a greater volume than a liquid fuel so it tends to displace more of the air in the available space within the combustion chamber. In simple terms LPG takes up more space to give the same amount of energy as a liquid fuel.

To compensate you naturally open the throttle more to let more air in, the additional throttle opening over what you would normally use on petrol increases directly in proportion to the amount of work you're asking of the engine and the percentage economy loss follows in direct proportion.

Interestingly the other way to compensate is to compress the air, not only are you effectively increasing the compression ratio and so the volumetric efficiency of the engine, you are also making the air more dense so there's more room for that air displacing LPG.

Yet more reasons why LPG & forced induction make such happy bedfellows

If I'm honest what I've found so far surprised me, on petrol the difference between driving in town & driving on the motorway is a 35% improvement, however on LPG the improvement between town & motorway is a much smaller gain of 20%. Being an air displacing volume thing it'll be the same for any LPG conversion, but not many will achieve a 17.7% loss at 80-85mph.

While all this is interesting (to me), what really matters is the 40-45mpg cost equivalent I'm regularly enjoying with no loss in performance. Anyone claiming they're getting much better than this from their LPG TVR is either buying their LPG at a crazy low price where the petrol is very expensive, or they're getting a little confused with how to work out their cost equivalent figure properly.

Very interesting Dave .I would like to use the car more but what does stop me is cost .I`m earning half the amount from five years ago and everything has increased in price .

What did alarm me is a trip from Nottingham to Stourbridge and back, cost me £70 ,that`s just to much for me. .I`m not bothered about using loads of fuel when i boot it ,that is to be expected but it would be nice to achieve 40mpg on a steady run ,this would allow me to cruise to places i love like Cornwall .


So its ether just do low mileage or get rid . I want to keep the car and actually use it so LPG may be the answer .The problem is i have used companies in the past who have made a complete mess so that worries me .Whats made things even more complicated is the way you explained how to get it fueled ,I would expect most of these LPG installers would not have a clue how to map the Emerald .Thanks Daz

[ChimpOnGas]

SILICONEKID345HP said:

Very interesting Dave .I would like to use the car more but what does stop me is cost .I`m earning half the amount from five years ago and everything has increased in price .

What did alarm me is a trip from Nottingham to Stourbridge and back, cost me £70 ,that`s just to much for me. .I`m not bothered about using loads of fuel when i boot it ,that is to be expected but it would be nice to achieve 40mpg on a steady run ,this would allow me to cruise to places i love like Cornwall .


So its ether just do low mileage or get rid . I want to keep the car and actually use it so LPG may be the answer .The problem is i have used companies in the past who have made a complete mess so that worries me .Whats made things even more complicated is the way you explained how to get it fueled ,I would expect most of these LPG installers would not have a clue how to map the Emerald .Thanks Daz

Get someone to do the hardware of the conversion (tank fitting, pipe work, vaporizer fitting ect) then get someone who knows the Emerald system to finish off the wiring and mapping.

Better still get someone like Lloyd Specialist Developments or Kits & Classics to do the whole thing.

Remember you only need the LPG piggyback ECU for it's peak & hold injector drivers, map one for petrol so if you're happy with that don't touch it, map two for LPG.

Keep in mind if you're consuming 20% more fuel with LPG you'll also need to carry 20% more of it to give you the same range. In my opinion that means ditching the 12.5 gallon TVR petrol tank unless you want a big ol gas tank taking up space in the boot.

Fabricate a frame and bolt to the rear body mounts then strap two stacked LPG tanks to that, this is not only a better use of space it's far safer too. You can then put a 4 gallon auxiliary petrol tank on top of that where Peter fitted his battery. With two low mounted swirl pots to stop fuel starvation on hard cornering you'll have a 5 gallon capacity which is very practical in itself.

Holding 65 litres of LPG takes me over 300 miles so very much the same as the petrol only car, and of course I've also got an additional 130 miles of petrol if I need it.

Remember however, more fuel means more weight and while the LPG tanks themselves hardly take up any more room than the original aluminum TVR petrol tank they're made of steel so are quite a lot heavier. If you carry a full 5 gallons of petrol then fill the LPG cylinders with 65 litres of gas it adds about 30kg to the back end of a standard petrol Chimaera.

To be honest all I've really noticed from this additional weight is better corning grip & traction, but I may still choose to fit slightly heavier rear springs this year.

If you do complete the conversion you'll definitely use the car a lot more, and remember its all easily reversible. But I've found once you start enjoying over 40mpg from your TVR you'll find it very hard to go back.

Nottingham to Stourbridge and back can't be much more than 150 miles can it?, if you burnt £70 worth of fuel at current prices you must have been doing 11 mpg

You might want to check your figures mate

Edited by ChimpOnGas on Monday 12th January 01:42

[SILICONEKID345HP]

ChimpOnGas said:

Get someone to do the hardware of the conversion (tank fitting, pipe work, vaporizer fitting ect) then get someone who knows the Emerald system to finish off the wiring and mapping.

Better still get someone like Lloyd Specialist Developments or Kits & Classics to do the whole thing.

Remember you only need the LPG piggyback ECU for it's peak & hold injector drivers, map one for petrol so if you're happy with that don't touch it, map two for LPG.

Keep in mind if you're consuming 20% more fuel with LPG you'll also need to carry 20% more of it to give you the same range. In my opinion that means ditching the 12.5 gallon TVR petrol tank unless you want a big ol gas tank taking up space in the boot.

Fabricate a frame and bolt to the rear body mounts then strap two stacked LPG tanks to that, this is not only a better use of space it's far safer too. You can then put a 4 gallon auxiliary petrol tank on top of that where Peter fitted his battery. With two low mounted swirl pots to stop fuel starvation on hard cornering you'll have a 5 gallon capacity which is very practical in itself.

Holding 65 litres of LPG takes me over 300 miles so very much the same as the petrol only car, and of course I've also got an additional 130 miles of petrol if I need it.

Remember however, more fuel means more weight and while the LPG tanks themselves hardly take up any more room than the original aluminum TVR petrol tank they're made of steel so are quite a lot heavier. If you carry a full 5 gallons of petrol then fill the LPG cylinders with 65 litres of gas it adds about 30kg to the back end of a standard petrol Chimaera.

To be honest all I've really noticed from this additional weight is better corning grip & traction, but I may still choose to fit slightly heavier rear springs this year.

If you do complete the conversion you'll definitely use the car a lot more, and remember its all easily reversible. But I've found once you start enjoying over 40mpg from your TVR you'll find it very hard to go back.

Nottingham to Stourbridge and back can't be much more than 150 miles can it?, if you burnt £70 worth of fuel at current prices you must have been doing 11 mpg

You might want to check your figures mate

Edited by ChimpOnGas on Monday 12th January 01:42

Thanks .I think i get it ,map two will have a bespoke map done on the rollers ,it will not be copying map 1 and the lPG ECU is just for the drivers .

Would the Piggyback ECU change the spark timing when used in the normal way ? If not is that the reason fpr the bespoke map ?

[ChimpOnGas]

SILICONEKID345HP said:

Thanks .I think i get it ,map two will have a bespoke map done on the rollers ,it will not be copying map 1 and the lPG ECU is just for the drivers.

Correct.

SILICONEKID345HP said:

Would the Piggyback ECU change the spark timing when used in the normal way?

No, LPG piggyback ECUs don't do anything with ignition, that's their big failing, they only work on the fueling by twisting the petrol injector durations to try and get things right for LPG

SILICONEKID345HP said:

If not is that the reason fpr the bespoke map ?

Your Emerald will be mapped on map 2 to give the optimum ignition advance for LPG which burns very differently than petrol, your Emerald would also be mapped on map 2 to give the optimum LPG fueling.

With a stand alone ECU like your Emerald the main mapping function of your LPG piggyback is no longer needed as you'll be mapping it correctly for LPG in the first place rather than trying twist the petrol map to get things right for gas. As I've said before all you really need the piggyback for is it's peak & hold injector drivers.

The only other useful feature a piggyback ECU offers that you may want to make use of is compensation for LPG pressure & temperature, 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, if you run the car open loop on LPG you'll find it impossible to maintain consistent AFRs as temperatures rise & fall.

This in turn will cause all sorts of running issues like surging, stalling, over rich, & over lean conditions. The solution is to run the car in closed loop, set your AFR targets and let your Emerald ECU make constant small corrections to follow those targets as it references the wide band lambda sensor many times a second.

In addition to the essential closed loop strategy there are some potential benefits in utilising that LPG volume correction feature most LPG piggyback ECUs offer. By creating an LPG volume correction table you can potentially give the Emerald ECU an easier life in closed loop.

In theory that means even more consistent AFRs which in turn means even smoother LPG operation.

[SILICONEKID345HP]

ChimpOnGas said:

Your Emerald will be mapped on map 2 to give the optimum ignition advance for LPG which burns very differently than petrol, your Emerald would also be mapped on map 2 to give the optimum LPG fueling.

With a stand alone ECU like your Emerald the main mapping function of your LPG piggyback is no longer needed as you'll be mapping it correctly for LPG in the first place rather than trying twist the petrol map to get things right for gas. As I've said before all you really need the piggyback for is it's peak & hold injector drivers.

The only other useful feature a piggyback ECU offers that you may want to make use of is compensation for LPG pressure & temperature, 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, if you run the car open loop on LPG you'll find it impossible to maintain consistent AFRs as temperatures rise & fall.

This in turn will cause all sorts of running issues like surging, stalling, over rich, & over lean conditions. The solution is to run the car in closed loop, set your AFR targets and let your Emerald ECU make constant small corrections to follow those targets as it references the wide band lambda sensor many times a second.

In addition to the essential closed loop strategy there are some potential benefits in utilising that LPG volume correction feature most LPG piggyback ECUs offer. By creating an LPG volume correction table you can potentially give the Emerald ECU an easier life in closed loop.

In theory that means even more consistent AFRs which in turn means even smoother LPG operation.

What afr`are you looking at for low speed driving ,cruise ,and maximum power .

I know its cheeky but do you have the blue print for your petrol tank ?

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 ?

Edited by SILICONEKID345HP on Monday 12th January 21:40

[ChimpOnGas]

SILICONEKID345HP said:

What afr`are you looking at for low speed driving ,cruise ,and maximum power .

I know its cheeky but do you have the blue print for your petrol tank ?

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 ?

Edited by SILICONEKID345HP on Monday 12th January 21:40

God, this is like 20 questions

I've tried to help but you've now turned the post into Daz's personal "build me an LPG conversion" help line.

Just start at page one and read, its all there.

Top tip.... if you're serious about doing it sooner or later you'll actually need to pay someone real money to complete the conversion for you.

Don't take this the wrong way mate but you can be a bit annoying, fortunately you invariably compensate for this trait with your frequent comedy moments

PM me if you want more detail & I'll be happy to help, until that is I get bored with all your questions, which I am right now TBH

Put everything you want to know in one email, that way you're not constantly asking me little detail question after little detail question over & over again one after the other.

[SILICONEKID345HP]

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 ?