well in all honesty this 2 week install is like gilligans island.... was supposed to be a 3 hour tour, a 3 hour tour.

But on the upside almost 3 months later its almost done and for less than the rebate $$$$

The twin su lpg fired ran and drove for the first time since 27th dec 2007 today, and fired first time.

It did start and roughly idle 2 weeks ago but had an issue every time you started the car, it would backfire lpg out the carb like a shotgun blast!

ends up bening the hitachi style su are different even in the intlet to the su slightly and this was causing an air flow issue with lpg bouncing off the edge of the su creating turbulance from the jets and the plunger in the su and causing the shot gun blast.

It idled ok after that though. didnt rev all tht clean.

but now.. its like a new car (havent driven it yet but heard it). just awaiting final tuning on dyno for mixture levels (he doesnt do power figures or runs, only for mixtures) and tidying up of some wiring.

but as sus sat for so long one of the plungers is slower on the up take to about 2500rpm then raises freely, seems like might be gummy or need a quick emery on the shaft to make it slide more freely.

48lt of useable gas and didnt take up much more room than the stock tank and lines, lpg filler is even fitted behind stock fuel filler lid for stealthness.

Close to done and pictures to come soon, camera phone sucks in the workshop.

so its that easy...

good stuff, i'll be interested to see how she goes on the cruise.

hehe other than a little slower to spool up, the LPG will show some nice benefits when you can keep your foot into it while all the petrol vehicles start detonating...

and the money you save...

Good stuff unfam another bbq powered datto on the streets lol keen to see how uve set it up to

G'day unfamilia. This lpg setup has been done before. In 1994 by myself and it may prove to be an engine melting nightmare. I will let you know where I went wrong with the setup and what I had to do in the rnd to fix it and make it run like a champion.

The first thing is that a 'simple' lpg mixer is a venturi type mixer. The smallest part of the mixer needs to be approx 25% smaller in diamater than your throttle body butterfly's to provide enough neg pressure to effectively draw against the convertor. I used amos mixers from a rover 175cd stromberg and they were almost the same size as the su throat and it caused lean mixtures. It ran smooth and revved but it leaned the L18 to the point of melting the bronze valve seats fitted as standard. New head fitted same problem with the 4gas annalizer.

Second problem is that when you use the plungers of the su you are effectively robbing the lpg mixer of its response from the throttle plate thus weakening the vacum signal to the lpg mixer. The lpg has to not only get past the mixer but the loaded plunger designed solely for the purpose of wet fuel delivery. It is why the su is a 'constant depression' setup. If the mixer size is right and you have enough restriction in the mixer to effectively feed the engine it would be of benifit to remove the plungers so there is only one venturi.

The most effective way to run a twin mixer setup is to use 2 constant depression lpg mixers. 2 impco 125 mixers.

I genuinely hope you have no trouble with yours as your mixers look different to the ones I used but they were designed for a 175 throttle body and not a 150 like yours.

If it does cause problems then I have a spare lpg manifold I made suited to a worked motor for straight lpg. 'VL throttle body and mods to suit either simple or complex mixer' Feel free to give me a pm or call. I am AAFRB accredited and have played with many types of systems although I am far from an expert.

Hope it works well. Don 0418253351

might come and see you don after its up and running, those bbq burner style mixers were what caused the problem with the backfiring, have inserted vk efi commodore venturis into the air stieam using the burner rings as housings.

The only problem with the su lpg set ups is getting enough draw on start up but with the mixer im using it has a bit of pressure in there that helps push the gas out into tthe air stream. This is as the su set up on start up doenst have as much draw for the gas as a conventinal single inlet set up.

the plungers are pretty much redundant with lpg As i inderstand as the butterfly at the back of the su does most of the metering in the inlet side of things and may insert helper spirngs to keep the plungers raised a bit so they done block off air flow completely, but once again this will affect draw of the gas.

As you would understand, its all a matter of seeing what works with this kind of set up to get it running, no off the shelf kits really available.

Its on an a15 with mild cam so may not be as bad as the L18 melt down, but atleast it may warrant a L series conversion if it all goes wrong (hope not)

i have an OMVL system it's been good, it's kind of hard to tune without a proper gas analyser, but i run a propane only system, with a variable venturi mixer, somewhat like an SU carb, it might run a bit lean according to the o2 sensor, the EGT hasn't been too high, so i don't know that melting engines is a problem, i ran mine hard for 9+ hours on several occasions and it didn't hurt anything when the engine was apart for the un-related oil pump fiasco.

I was thinking...

A15's came as lpg forklift engines and other industrial apps. so melting engines is not a common problem.

dual fuel systems tend to not work well on either fuel.

fork lift engines dont want to rev to 6500rpm either, they max at 4000 due to cam i think from memory.

dual fuel is waste of time for performance, its one or the other. with a bit of a head skim to bump up compression, will make more power again.

had to remove venturi system and go back to burners, they provided too much gas on tuning, good cold start up but too much gas, couldnt be restricted enough. convertor can pump enough for a 3ltr motor!

Put restrictors into the inlets of the burner style lpg mixers, great cold start up and good all round flow, still on the richer side but not overly. Final tuning on monday for all rev ragne mixtures etc.

I recommend OMVL... impco is old technology more suited to tractors...