LPG Tuning On The Cheap.

[Beefy Laser]

hey,

Im not much of an expert on the tuning of LPG or carbs, so heres the scenario.

Mate has bought a 88 Mazda E2000 van, plans to use it for his plumbing business, so gonna carry around 300kg in tools and shit, and about 500kg in beer

Engine is the FE 2 litre sohc carby job. It is dual fuel with a cheap and nasty gas install. Runs mmmokay on petrol but gutless as a sissy on gas.

So he says to me, how can i give it more balls on gas? and make it use not so much as its chewing thru gas its goin outta fashion.

any ideas?

Having a look at the gas system, its all pretty cheap. The carby is just used as a TB when the gas is on. Small converter underneath the van. The mixer looks like a round piece of pipe put inbetween the air cleaner and the carb, and the gas enters thru a pipe in the side. There is no vacuum lines or anything going back to converter. So how does it know how much gas to use??? and how do you stop it using too much and bogging? coz baby it bogs bad. there is a needle valve adjustment for the gas but this seems way too crude for any decent quality to be obtained.

what sort of IGN timing and dwell would the lpg like? and what soft of mixture...lean or rich?

And the other thing is the air filter is a big cylinder pos thing. Worth putting a pod on instead?


open the floodgates...

thanks all.

Beefy.

[Beefy Laser]

i know this is not really the usual 'performance' kind of thread, but it does keep in with the DIY theme on here.

but a gas van with balls.... would be hell funny if it could light up the backs

anyone....

[steevo]

By its very nature you will use more LPG than petrol due to its lower BTU figure so you wil always be slightly behind petrol in economy stakes but the price of LPG evens it out.

To maximise LPG performance you should close the plug gap a little as LPG is harder to ignite and ideally you should have more inital timing and less total but the dizzy should be recurved to achieve this or the fitment of a dual igntion curve box may be better.Also the coil and leads should be in top notch condition as LPG will show up any inadequecies (sp?) of the ignition sytems.

As for the bogging down,Take it and have it put on a 4 gas analyser and have the mixtures set correctly.

Steve

[Beefy Laser]

steevo,

I agree with you fully about using more LPG by nature. I am led to believe that it is in the vicinity of 20/30 percent more than petrol. But the thing is getting like 100km to a tank and its a standard size tank apparently, not sure if its 30 or 50 litres.

Davo (van guy) says he has set the static timing at 10degs advance and dwelling at 40 i think he said. I believe the leads are shithouse so thanks for that point. Spark plugs are dead stock ngk's which makes them about 0.8-0.9 gap.

I once heard that lpg likes running with colder plugs, any truth?

He is a stingy bastard so i cant see him taking it into repco for a 4gas analysis. I mean as far as i can see, the only adjustment whatsoever for the gas system is a needle valve in line with the mixer, THATS IT! i cant see how this would work in relation to load/rpm and run at all. will pass that on though.

My thought was to run a HEI ignition box (diy kit jobby). Gives an extra 10 degrees dwell extension and fatter spark. gotta be good for lpg right? cant see him dishing for the jaycar key pad programmable one though... prolly would be better.

thanks for the info.

[steevo]

Beefy Laser,

On sole LPG motors like mine i run 2 or 3 numbers colder than standard due to LPG`s clean burning properties and ability not to foul up plugs and also becuase my motor has got a hefty increase in compression,But on a dual fuel stock motor i would leave them alone especially if it burns some oil as the plug tip needs to get hot enough to "self clean" or you may end up with missfires etc due to foulded up plugs.

Really the only way to get the mixtures right (wether it helps with the bogging or not im not sure) is to have it on the analyser but the up side of this is the economy might be helped if its running too rich.

Steve

[mopar lover]

That motor is a piece of shit !

A mate had an 2000 E2000 with a factory dual fuel setup. If the install is anything like the factory impco setup its all crap. The pipe between the mixer and carby is a restriction. I couldn't get his car to idle properly in gas or petrol with the pipe on. Pulled the pipe off and the idle actually went up 50 rpm. The van had 2 speeds slow and slug (gas). The only way I know to curb the gas consumption is to be VERY conservitive with the throttle. I used twice as much gas as my friend when I drove the van.

As a note vans are not fully tax deductable, so he got rid of it and got an AU XR8, which now uses less petrol even with him regularly giving it some.

[van318]

there is no way you can get it to run well when it is not dedicated to one fuel,or the other.
When tuning to run on both,there are a lot of compramises that have to be made.
If you piss off one or the other,you should then be able to get it to run better.

[carazy]

you can make youself a mixture sensor as found on autospeed.com.au
put this in the exhaust and turn the gas feed mixture setting till it's in the middle (it's a small valve on the hose going in to the carbi)
that way you can tune it yourself and get it near on perfect everytime.

[Beefy Laser]

steevo,

the spark plug thing is a good point. I think he runs it like an hour a week on petrol, but who knows. It is handy having duel fuel coz the gas seems to die quickly when it runs out, so a quick flick to petrol is always good. so i guess the standard heat ranges stay.

mopar,

i see your point but dont fully agree. The motor has done almost 300,000km and its original, and runs pretty well for its age. Idles pretty damn good for a oldie, but power delivery leaves something to be desired. maybe the 2000 model was a little worse who knows.

slow and slug haha it seems like that. When we go out on jobs and have to go uphill like the freeway its 50 in 110 zones for a whyle.... just wont go faster. Its funny with the gas, more u floor it, more it bogs and slows down. tuning issue im sure. Davo cant be conservative with throttle, as he is basically a feral and doesnt know how to stick to rules and speeds. but good point though.

vans not tax deductable. had no idea at all. Told him u said that and he said he's allowed to depreciate 100% on tax over 4 years. hardly worth it for 3g though.

van,

i agree, the simpler the better. rip off the carby and put a TB on and would be so much simpler. But duel fuel is handy though. good point.

carazy,

moving swiftly to look that up... cheers mate!


thanks all. any opinions on the finer points like ign timing, dwell and mixture ratios?

beefy, on behalf of a lazy prick who stinks