Why Don't We Run Gas?

[JoelyMoley]

hey guys, just been reading a bit on LPG and finding websites stating the minimum RON of LPG is around the 99 mark, which got me thinking whats stopping most skyline drivers from jumping on the LPG band wagon, 50-60c/L fill-ups sound like a godsend to me, not to mention the higher run would technically equate to better performance no? sorry if this is a stupid question im just genuinely interested (thats what sitting on a computer all day at work does to ya! )

thanks guys!

[zebra]

Mainly because Even the very best LPG systems dont support big HP...and the fact that there isnt much room to mount tanks in the car...and oh...LPG is for Taxis

[GTScotT]

+1 annoying to mount a tank and poorly developed LPG systems

[JoelyMoley]

Mainly because Even the very best LPG systems dont support big HP...and the fact that there isnt much room to mount tanks in the car...and oh...LPG is for Taxis

ah ok, so the limiting factor would be injectors or? lol i wouldn't mind sacrificing my boot for that kind of saving at the bowser! must admit i would feel like a complete knob-jocky grabbing that lpg pump at the servo lol

[Messiah]

i read an article some time ago that stated that injectors where the biggest hold up, however some mob claimed to have fixed this problem.

I think its an issue of fuel density and injector speed... but it was a looonnnggg time ago.

[zebra]

Its also a gas flow issue when the tank is getting low...the pressure drops right off.

[TiTAN]

ah ok, so the limiting factor would be injectors or? lol i wouldn't mind sacrificing my boot for that kind of saving at the bowser! must admit i would feel like a complete knob-jocky grabbing that lpg pump at the servo lol

i did the math a while ago and to run 350kw you needed 18 of the largest LPG injectors that were on offer. not to mention a computer capable of controlling all 18 properly.

[STATUS]

hey guys, just been reading a bit on LPG and finding websites stating the minimum RON of LPG is around the 99 mark, which got me thinking whats stopping most skyline drivers from jumping on the LPG band wagon, 50-60c/L fill-ups sound like a godsend to me, not to mention the higher run would technically equate to better performance no? sorry if this is a stupid question im just genuinely interested (thats what sitting on a computer all day at work does to ya! )

thanks guys!

Propane (the better gear) only yields about 86% of energy per volume of petrol but is partially compensated by the higher stoich of 15.6:1.... so it always yields lower results... ie a step backwards.

Tank pressure is the biggest issue, much like nitrous a lpg tank needs to be stabilised temp wise to deliver consistent pressure otherwise your mixtures change with the seasons or days etc... simply dangerous for high output engines. Much has been done lately to alleviate these issues including running fuel pumps inside the LPG tank and a pressure regulator. Currently around 700hp is the sensible limit of these kind of liquid injection systems Normally Aspirated

[N1GTR]

There was a thread in here a while back about a GTR being converted to gas.

Also there's one semi regular forum member in Sydney with a stagea on gas. The tank is where the spare wheel goes so it's not that bad

[JoelyMoley]

There was a thread in here a while back about a GTR being converted to gas.

Also there's one semi regular forum member in Sydney with a stagea on gas. The tank is where the spare wheel goes so it's not that bad

until you get a flat that is

like i said, not looking to do it myself but was just wondering, yea the stag gas driver is was prompted the rare brain activity during work

[89CAL]

lol it is sorta a good point, why does noone do it.... but when my brain thinks any further then that i just think

"skyline filling up with LPG and running on LPG, thats not right"

like i said, good point but i wouldnt want to do it to my skyline and i dont know many others that would either lol just seems wrong

[clip14]

from the top of my head there are a few reasons why. LPG injection systems were a bit behind the times for a long while, only recently are there decent fuel delivery methods to deliver a pressurised gas into a internal combustion application.

the other reason as prev stated also is the availability, fitting and weight of the gas cylinders required. This has changed recently with composite cylinders becoming widely used and affordable. nowadays you can get a torus shaped cylinder which will fit in your spare wheel well.

so all in all, a lot of the reasons why lpg was never used in the past have now been solved, the old ideas are still prevalent though which explains why not many people use it.

lpg has a higher effective octane rating which means higher compression/boost/timing can be run.

the cost per litre is also cheaper, although balance this out with the fact that lpg is less energy dense (energy per volume) than petrol, along the same idea as how larger injectors are required to run e85 (since its less energy dense than petrol, requiring more to support the same power levels).

the ongoing cost savings are there, if you can work your head around the setup, then it may be a worthwhile idea.

[urtwhistle]

My R34 GTT is dual fueled, and paid for it self in about a year. like previously said the main problem is Line pressure and the tuning to make it work, esp with a vapour sequential injection set up like mine.

1 work around is to run dual gas lines, dual convertors and dual injectors. (highly ugly and impracticle).

Liquid injection is 10x better, no gas convertors, constant fuel pressure as there is a pump in the gas tank and alot less wiring. and allot higher power capabilities.

another trick is to trigger the gas computer to revert back to running on petrol once a set rev or load point is hit.

regards

Chris

[NYTSKY]

If you had a modified N/A skyline you could get it to run gas no problem. And make a few extra KW with the liquid injected systems.

I was looking into these with a modified Falcon i use to have but the cost of the conversion put me off. Was about 5k from memory.

[MrStabby]

Gas injection is old skool. I've heard the XR6T boys are having great results with liquid LPG injection. Thanks to boyle's law it makes more power than 98, and the effect to especially beneficial on forced induction engines due to the heat added by the compressor. The biggest problem for them is limited supply of the kit making it difficult to source. I havent looked into it myself - all this info is second hand.

[STATUS]

Gas injection is old skool. I've heard the XR6T boys are having great results with liquid LPG injection. Thanks to boyle's law it makes more power than 98, and the effect to especially beneficial on forced induction engines due to the heat added by the compressor. The biggest problem for them is limited supply of the kit making it difficult to source. I havent looked into it myself - all this info is second hand.

power has never been a problem, its mixture stability thats the main issue and those new "fandangled" liquid injection systems you talk of are still having injector freezing issues at high hp.

attached is the 700hp engine i was talking about aerlier on the engine dyno, running a aeromotive 1000 pump and in tank and regulator, ecu compensation for pressure is clearly seen on the fuel rails.

[zebra]

also all the Liquid injection setups can only run 4cylinders so you need two kits for a 6 or 8

[JoelyMoley]

if its problem is with big hp, wouldn't a fairly stock GTS-T a duel fuel setup of gas for general light driving and 98 for some heavy fun be a ideal setup? im a absolute nub at the workings of LPG so im obviously missing something as it still feels like a win-win in my books

[zebra]

the extra weight will hurt the performance big time.

if you really wanna got for cheap fuel convert to E85 or even have the car detuned to run on 91 ULP.

or keep the 5k and whack a Gt3037 Pro S on the car

[JoelyMoley]

the extra weight will hurt the performance big time.

if you really wanna got for cheap fuel convert to E85 or even have the car detuned to run on 91 ULP.

or keep the 5k and whack a Gt3037 Pro S on the car

like i said, by no means am i looking to go gas on the liner, was just curious if their was a viable technical reason for the lack of gas powered sports cars and thats been explained fairly well

out of the 3 their i definately know what my young impressionable mind steers towards