GTR conversion to LPG

[thedriver]

I'm considering a conversion of either an R33 or R34 GTR to run solely on LPG. Does anyone know someone with the experience and knowledge that I could discuss this with?

Or does anyone have any information regarding it? I don't know of any LPG GTRs...

[NFS]

I don't know of many LPG GTR's either actually anyways you'd be best going for LPG injection I reckon..... Hard to get now but you can get it apparently it will give you the same power as normal.

[DAN00H]

from my understanding the LPG injection hasn't yet been fully developed. the idea was to inject it as a liquid, not a gas, as normally happens with gas cars. I heard there were problems in the conversion process.... there was an aussie company developing this system - if sorted, would totally kick arse!!! 110 octane!! and dirt cheap

As for running the 'normal' LPG, I've seen in mags turbo injected cars running it - mostly rotors. there was a mob in Melb that developed a kit to go on late model fords that used a screw supercharger and lpg system. (in one of my old zoom mags a believe???) I'd be very interrested in seening this done, but one of the problems is the burn rate of the LPG, which is slower than petrol - hence the research into gas injection. Email MD from zoom and ask him??? I'd do this with my GTR as well - think of the benefits!!!

[rev210]

It would work ok. But, always lower in power for the same setup against your BP98 fuel.

The only reason you do this is for ecconomy. Full stop. Irespective of the system you use.

It would be a complete bastard to get the hardware into the already cramped engine bay too.

[DAN00H]

It would work ok. But, always lower in power for the same setup against your BP98 fuel.

The only reason you do this is for ecconomy. Full stop. Irespective of the system you use.

It would be a complete bastard to get the hardware into the already cramped engine bay too.

I've seen cars running dedicated GAS produce more power when tuned for it than on 98 petrol. test case was a ford 460, 11:1 compression, originally set up for perimum petrol, motec injection etc tuned properly. owner found it very heavy on juice and decided to convert to dedicated LPG, following all the proper changes and tuning, it made more power that it did on petrol - same tuner, same dyno etc, no other mechanical changes....

[rev210]

DANOOH,

If I take your example then I must say the reason it doesn't follow the 'fact' that LPG cannot produce the same power is that you stated "..no other mechanical changes...."

You are probably aware that the combustion and flow characteristics of LPG dictate a need for an appropriate LPG camshaft design to make it work well. If the guy did not change anything and got more power with LPG then I can only say the original config was not tuned correctly in terms of camshaft timing or something fundamental like that. Or the camshaft profile was a poor choice to begin with. A true 11:1 ratio is also outside of the optimum compression ratio for an LPG dedicated 460, it ought to be around 10:1 not withstanding a rather huge solid camshaft profile to make it work best at very high compression. I would guess the pistons in that are flat tops and not concave style which LPG works better with too. At the end of the day at least the guy can rebuild the 460 later on and get better power doing it right.

If you question the guys at 'gasresearch' who make the dedicated performance gas carbies I'm sure they will tell you why they can get sort of close to straight fuel but, not beat it in terms of power for an equivelent optimised engine. Let me put it to you there are no race teams pushing the straight LPG barrow for the sensible reason that it can't produce the same power at a decent level of competition.

Diesel is a different kettle of fish though.

[DAN00H]

DANOOH,

If I take your example then I must say the reason it doesn't follow the 'fact' that LPG cannot produce the same power is that you stated "..no other mechanical changes...."

You are probably aware that the combustion and flow characteristics of LPG dictate a need for an appropriate LPG camshaft design to make it work well. If the guy did not change anything and got more power with LPG then I can only say the original config was not tuned correctly in terms of camshaft timing or something fundamental like that. Or the camshaft profile was a poor choice to begin with. A true 11:1 ratio is also outside of the optimum compression ratio for an LPG dedicated 460, it ought to be around 10:1 not withstanding a rather huge solid camshaft profile to make it work best at very high compression. I would guess the pistons in that are flat tops and not concave style which LPG works better with too. At the end of the day at least the guy can rebuild the 460 later on and get better power doing it right.

If you question the guys at 'gasresearch' who make the dedicated performance gas carbies I'm sure they will tell you why they can get sort of close to straight fuel but, not beat it in terms of power for an equivelent optimised engine. Let me put it to you there are no race teams pushing the straight LPG barrow for the sensible reason that it can't produce the same power at a decent level of competition.

Diesel is a different kettle of fish though.

:Oops: Rev210 - I stand corrected, I meant to say that the engine received no additional things ie headers, manifold, pistons. Yes, cam and disy were changed for gas specs, pistons etc were same as petrol build.

The car belongs to my older brothers friend, and will look into obtaining more details, it also had better MPG?!?! He did not use Gasresearch, but a modded 4 barrel - same style that my brother uses on his dedicated gas fairlane. LOL.

They use odd spark plugs, which tested well with the burn rate of LPG.... I trailled after a little while on the conversation.

oh, also used different thermostat

I'd imagine LPG would be no good in racing, but perhaps in LP form it would be used (providing someone sorts the injection issues - again, I wasn't really listening to the problems assocated with doing it etc, but pricked up my ears when they said inject LP + cooling properties of injecting the stuff!)

[awurth]

I guess people wouldn't use it for racing because of it being held in a pressurized vessel? After talking to various people I always believed dual fuel cars to run with less power in the LPG setup cause the car is tuned for petrol and the LPG requires more advanced timing to run properly. So I guessed that with a slower burn rate it must have a higher ron rating so you could pull more power out of it. just my guess. you wouldn't want to try put anything in the boot of the GTR if you did the conversion cause with the tank in there I can't see there being much more room. interersting to see some results.

[DAN00H]

I guess people wouldn't use it for racing because of it being held in a pressurized vessel?  After talking to various people I always believed dual fuel cars to run with less power in the LPG setup cause the car is tuned for petrol and the LPG requires more advanced timing to run properly.  So I guessed that with a slower burn rate it must have a higher ron rating so you could pull more power out of it.  just my guess.  you wouldn't want to try put anything in the boot of the GTR if you did the conversion cause with the tank in there I can't see there being much more room.  interersting to see some results.

LOL, I've seen firsthand the results of a ruptured gas tank - not pretty! lot worse than a ruptured fuel cell!!! Agreed, duel fuel is a compromise, I'd only use dedicated Gas, most Fuel injected cars use the petrol on start up though - hence the reason they are duel fuel. If I was running a GTR on Gas, I'd replace the petrol tank with a gas tank

[rev210]

LPG . It good at providing an ecconomical alternative, for the power chase it's a compromise.

You can do things to minimise the compromise but, it still stands as one. Even with LPG injection you won't get better than good old BP98 when the engines are tuned well for both.

Race enviroments probably don't like the pressurised tank, they like less the fact that LPG can't get the same power as BP98 let alone C16.

This does not mean to say you can't pull some great power for a street application out of an LPG system if things are matched well. The limits of power generation are quite high none the less with LPG.

[FATGTS-R]

my friend has a drag set up rodeo and it was originally duel fuel before he went crazy with power mods.

He also heard about these gas injectors and investigated and ran into the same brick wall. They were "under development" and not quite ready.

Dont quote me, but from memory one of the problems was the injectors freezing up ( apparently they ran OK in QLD but try run them in colder climates and they were cactus )and they were looking into a way of heating them or similar but the end cost was going to be way over the top for the hardware they needed to use to heat them or something along those lines.

[DAN00H]

thedriver - have you done any research into it?

[proengines]

One quick question... Why would you want to convert to LPG?

The reason you probably dont see any LPG GTR's around is because there aren't too many GTR taxis or courier vans.

Until someone perfects LPG injection you would need to run a blow through gas carby setup which would be a huge step backwards. You would end up with poorly metered fuel running through an intake setup not designed to carry anything but air. The ignition timing would need to be changed to suit the lpg, so you would need a separate ignition computer. The octane rating of LPG varies depending where you buy it, a lot of it is now apparently mixed with butane as it's cheaper. Then you need a tank in the boot to hold the gas, fit a converter or two in the engine bay somewhere etc.. etc..

This is before you even consider the accelerated wear on valve seats, the tappet clearances closing up, the lack of upper cylinder lubrication and cooling provided by petrol, the increased chance of detonation, not to mention the valve timing which would need to be changed to run efficiently on LPG.

If you then weigh up the cost of the conversion compared to the fuel savings.. say $3000 at a very minimum, the fuel usage, running LPG you may save 50c a litre but then each litre only gets you about 2/3 as far as a litre of fuel, so say a 60L tank of fuel will last you a week, you will need 80L of LPG to go as far, so $60 of petrol will get you as far as $40 of LPG. Thats about $20 a week you save or $1000 a year. Theres at least 3 years driving before you save a cent considering the cost of the conversion.

Finally, imagine trying to sell the car in a few years.. who would buy an LPG GTR?

[thedriver]

thedriver - have you done any research into it?

<{POST_SNAPBACK}>

Sorry - I let this slide a bit, didn't I???

I had done some research and not got very far. All the gas converters I spoke to had very little experience with turbo charged engines let alone a real performance vehicle like the GTR. Mostly the all did baby-cot carriers - fords and holdens...

I've actually changed my tak and realised that because of my lifestyle (snowboarding, scuba diving and mountain biking) I need a wagon... Enter Stage(a) left. Or maybe a Mitsubishi Legnum (but I don't think I can wait for compliance process)

Now I'm looking at either Stagea RS4 or RS260. Given my previous enquiry into the GTR, the basics still relate to the RS260, and hopefully the RS4 should be a bit simpler.

As for injected systems, Gen 3 gas injection has been available for some time and I understand that this does away with the mixer / carbie system that has been the trademark of LPG systems. There is also a system that was on New Inventors that claims to increase power... the GTi Stealth Injection System.

I've just sent Bill at GasInjection an email so hope to get some info back from him...

There was also a new LPG tank that I recently read about "somewhere" but can't find now, and it was more modular in design, more able to replace the existing petrol fuel tank and stronger.

But if anyone else has something useful I'd be willing to listen... especially given the lack of good advice that I have received thus far from the people in the LPG trade.

Cheers.

[psybic]

If you then weigh up the cost of the conversion compared to the fuel savings.. say $3000 at a very minimum, the fuel usage, running LPG you may save 50c a litre but then each litre only gets you about 2/3 as far as a litre of fuel, so say a 60L tank of fuel will last you a week, you will need 80L of LPG to go as far, so $60 of petrol will get you as far as $40 of LPG. Thats about $20 a week you save or $1000 a year. Theres at least 3 years driving before you save a cent considering the cost of the conversion.

Finally, imagine trying to sell the car in a few years.. who would buy an LPG GTR?

<{POST_SNAPBACK}>

So true. Good practical calculations there. Except one thing ofcourse... it was 50c difference. That gap is changing all the time. What about when it his $1 difference. Using this very good average calculations which I know would be about right for me. Suddenly its a $2000 a year saving. When oil gets worse, it will continue to make more and more sense.

Its about time LPG or another fuel source got some more serious thought.

Its like everyone always tries to be wise and predict fuel prices will hit $1, then $1.50, like they are clever or something, but its a no brainer, they will keep going up! As they do, we need to be on top of things and start some of the great mechanical minds out there think about this LPG setup. What about when the price difference is $1.50 per L! What will the difference be in 10years??

Who wants an LPG GTR? I do!!

[thedriver]

What about when the price difference is $1.50 per L! What will the difference be in 10years??

Who wants an LPG GTR? I do!!

<{POST_SNAPBACK}>

It's more than that though. I'm not just talking $$$ here, nor was only talking $$$ orginally:

LPG reduces wear on the engine...

it's cleaner burning....

You can run higher compression ratios....

it's better for the environment (wouldn't it be nice if the media caught on that "rev heads" were actually doing something positive)...

power loss has been virtually negated (or in some cases claims that power increases)... not sure about this though, as lpg contains less energy than petroleum

And yes... now that petrol prices are soaring the economy is looking even better if with the installation of an expensive system. Enthusiasist are hurting more than ever with the current prices and it will get worse (we all know that).

Does anyone know a good... no skip that. Does anyone know an EXCELLENT truly PROFESSIONAL autogas installer???

[tk80]

no....but speak to c&v in sydney. they know there stuff and have done this sort of thing in the past. ask for con

[The Mafia]

this is very interesting. I would love to go LPG... f**k the boot if its gonig to save me $50 a week.

Anyone done a successful conversion?

[psybic]

Who did the 10second VL's we always here about? That would be a good start.

[thedriver]

Who did the 10second VL's we always here about? That would be a good start.

<{POST_SNAPBACK}>

Very good point!

Edited September 29, 2005 by thedriver