Outer Limits 4x4 Board

just wondering if anyone else has a 100 series 4.5L duel fuel gas injection system and what kind of power difference they get from petrol compared to gas. My 1998 manual 4.5L hammers on petrol but on gas i reckon i loose around 20% power. I have a snorkel and i have noticed that when running on gas i can hear the engine making a tapping noise but as soon as you switch to petrol the tapping noise goes away and i get instant power. Just wondering if anyone has any idea's as to the power loss as my mechanic has dyno tuned it 4 times and cannot get it to match petrol.

gas system is eurogas

dazlin wrote:just wondering if anyone else has a 100 series 4.5L duel fuel gas injection system and what kind of power difference they get from petrol compared to gas. My 1998 manual 4.5L hammers on petrol but on gas i reckon i loose around 20% power. I have a snorkel and i have noticed that when running on gas i can hear the engine making a tapping noise but as soon as you switch to petrol the tapping noise goes away and i get instant power. Just wondering if anyone has any idea's as to the power loss as my mechanic has dyno tuned it 4 times and cannot get it to match petrol.

gas system is eurogas

And you never will get it to match petrol.

Gas injection should come very close to Petrol, and sometimes beat it for power.
The only thing it will never outdo is economy per litre.

Could be time to tune it, and service it, change the LPG filters etc.

i believe when an engine is tuned to gas it needs done under load 95% of gas installers just rev the car to tune it believing this is under load. you need to have it dyno tuned for best results, in my honest opinion though you will never get it to run as good as the petrol if you want it to run on both. however if you have it tuned straight to gas with petrol removed completely you may get it to perform a little better some may beg to differ, foor those people d your homework and see which has a higher octane, please prove me wrong

CRUSHU wrote:Gas injection should come very close to Petrol, and sometimes beat it for power.
The only thing it will never outdo is economy per litre.

Could be time to tune it, and service it, change the LPG filters etc.

+1

I'm running a '99 4.5l on Vapour Injection LPG. First off the tapping you hear is the gas injectors, its nothing to get stressed about. I was warned about this before I had mine converted. The gas injectors are pretty noisy.

As far as power goes I'm getting slightly more out of the LPG. I've tested it up a few long hills and found that she does accelerate faster on gas than petrol. Economy is a different matter though. On Petrol I'm averaging 17-19 l/100 but on gas I'm getting 21-24 l/100.

The wierd thing is that on gas the variance in economy is based on the load I'm carrying. Driving gently or hard, city or highway seems to make little difference.

LPGas 1 did the conversion and had the car for 3 days! Other's were quoting 1 day. These guys did the full dyno tune and road tune. I won't say that the conversion was painless (I did have a installation related problem) but I can't fault their service or how they responded to the problem that I had.

It sounds like you may have a tune issue. I'm really happy with the tune on mine, I can change from gas to petrol under load up a hill and you can't feel the transition.

my cruiser has heaps of gear on it and weighs heaps so my economy is allways going to be crap. on petrol it is around 23L/100 and on gas around 28/100. Mine switches between gas and petrol perfectly, i just want more power from gas so i think i might get it re-tuned. It has been dyno tuned 4 times by the same guy so maybe i need someone eles to look at it.

I know a guy that dyno tunes LPG in Hallam, if your interested, pm me.

i have a 98 auto ave 26l/100 km on both petrol and auto only notice a slight difference in power when switching to petrol from gas but other wise happy with it

You will never match the economy, but you can match or exceed the power with Injection, and dual fuel.

So did you get the snorkel after you had the gas tuned? Because if you did then you need it re tuned with the new airflow dont you? I have to get my gas re tuned because i got a new snorkel and air filter as well. But gas was painful to drive before that because i dont think it has been serviced in a while.

When I booked mine in for the gas injection they asked if I had cruise control or not. Any ideas what difference that makes ? Do they need to be tuned differently ?

maybe different wiring at the throttle body??

clownman wrote:i believe when an engine is tuned to gas it needs done under load 95% of gas installers just rev the car to tune it believing this is under load. you need to have it dyno tuned for best results, in my honest opinion though you will never get it to run as good as the petrol if you want it to run on both. however if you have it tuned straight to gas with petrol removed completely you may get it to perform a little better some may beg to differ, foor those people d your homework and see which has a higher octane, please prove me wrong

what if you ran a new computer with 2 timing maps? more advance for gas. all being injected shouldnt be any different than being dedicated gas or not.

MaccA

i got 2hp difference favouring gas, (105 series elko gas) what dyno did you get it tuned on?

have you got an equalisation thingummy (cant think of the proper name for it - help me out here guys) in the snorkel for the gas - this could be why you are getting crap power

I'm assuming they installed a piggyback ecu to handle the gas injectors and timing map adjustments for the gas?
My 3RZ is using Gas Research carby and has same power on petrol and gas, but on gas is using more fuel.
If you are anywhere near Dandenong, I can highly recommend Swift Automotive on Swift Way, off Dandenong-Frankston road. They dyno tuned mine, and have no problems fixing little issues or rechecking the tuning if there are any issues free of charge. Ask for Peter, he's a good bloke.

Another thought, if the gas injectors are making a fair racket, is it possible that they may be triggering the knock sensors to retard timing? May need someone with an OBD scanner to check if there is any knock retard occuring...?