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Direct gas injection

G'day all,

I'm thinking of putting my car on gas or direct gas injection. What the difference from direct gas injection and dual fuel. (apart from the cost, lol) Has anyone had any experience with putting direct gas injection on a 308? and is it possible to put direct gas on a carby feeded car?




duel fuel system means , LPG conversions are incorporated with the use of your present carburetor, the system is tuned at some place in between the duel fuel arrangements, and not really a good thing ,
Petrol setting on the dizzy should be 6 degree, LPG should be around the 10 degree, so they usually set the dizzy at 8 degree static, some place in between,
there is also a different curve on the LPG because of its high octane rating, also the curve on LPG, it sort of straightens out around the 1500 rpm mark, were as Petrol keeps on going higher up in the curve,
then there is the spark plugs, you really need two different heat ranges but only one is used,
not sure on the gas injection side ,others might comment on this, would like some feed back as i'm really interested in LPG set ups
so really the tune up for duel is not quite, 100%, still there are ways to get around this, you can have a management system or duel curve switch put in and change the curve etc ,it is suppose to work , don't know and have not heard of any body that has one ,but with modern cars that have duel fuel that come off the production line a guess that is what they have in all that electronic gadgetry,
on my set up, I can change my dizzy setting while driving , can set from 6 to 10 degree on the static setting, and I cut the vacuum line off when on LPG to reduce some of the curve, i'm still in the prototype stages of this at the moment (curve )but it seems to work for me, and of coarse hasn't cost me any $$$
however the BEST way is LPG only , positive feed cant go wrong, will be far better economy wise, and thats what your chasing as your talking LPG, check with Gas Research, also "Streetneet" Andrew ,has got a couple of good set ups with his LPG, not sure if he has pics in his sheds on it , will be changing mine to LPG only later on
Cheers, Jacks.
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Direct injection gas will only go on a fuel injected car - and is very expensive and complicated - especially if you want dual fuel - if it is straight gas it isn't too bad to put in as you just replace the fuel injectors with gas injectors - as far as I know though there is only 1 place advertising these systems and they have only really done it on a Magna - I would stick with the standard LPG setup - cheaper and proven that it works

premhg, what's the place you are talking about? I wan't to have a look-see just for interest's sake.
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Thanks for the info, i'm going to be doing some more reasearch into it. I did some research on my own behalf. Theirs a place called Knox Ford, in Victoria, they do direct gas injection. Yea only works on fuel injected cars. Keep me posted about your your prototype curve i'm really intereseted.



I'm interested in that LPG injection as well, so any information would be great
Cheers, Jacks.
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Sequential Vapour Injection has been popular in Europe for a few years now.
There are some aussie companies starting to get into it.
Have a look at:


There was also a couple of systems on ebay recently, but they were asking around $1800 for injectors and vapouriser.

Brett (bf6379)

Here's a link to an Aussie mob that do lpg injection - From what I understand they inject lpg as a liquid (i.e. no converter needed). Or go to Parnells website and look under sequential vapour injection - this is injecting vapour instead of liquid.



HQ Tonner with gas ...
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I had communication via email to Barry at Gas Injection Technologies about 6 months ago. At the time his system was very close to the end of the development stage, but he had nothing to sell. The system that I spoke to him about was also Sequential Vapour Injection and you do need a converter, although it is positive pressure, not negative pressure as used with the Impco mixers. The big difference with his system is that the injectors have identical electrical characteristics as the factory petrol injectors, so you dont need any additional electronics to drive the injectors. On most of the other SVI systems you need an additional LPG ECM that either runs alone or interfaces with the factory ECM. On most later model EFI cars, the ECM monitors injector current pulses and checks for ringing and other irregular pulse shapes and starts generating fault codes if everthing is not right.
The advantage of the LPG injection being sequential is that the gas is injected into the manifold right at the port only when that cylinder is on the intake stroke. This means there is no huge amount of gas in the intake manifold at any one time, no catastrophic backfires to blow the crap out of your air box. All the blokes that drive LPG V6 Commodores know about that.


I have just taken my car in to get the new gas vapour injection setup and so far so good, I went in today to look at it and the tank and computer are already installed.

HI car-on-vapour

me to, please
Cheers, Jacks
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Direct cylinder injection with gas is what we need!

"I've got grey news for you, its neither good nor bad." - Quote of the week from a co-worker.

Never Drive A Car Younger Than Yourself!

So this is only available on an "EFI" car. My 350 runs mechanical fuel injection and I can't see why this wouldn't work on my setup.

Just curious as to what type of mechanical injection are you running?

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hey guys my name is tyson i own an operate alltered gas equipment).i specialise in gas and direct gas injection on retro cars having doing it for the last coupla years.a few samples are injected on straight gas EB XR8 347 stroker std 5.0 litre cam 11.5 comp mild tune 250hp at f350 460BB 310hp at wheels.65 ford xp 302 winsder with gen3 multi coil packs 13.1comp mild roller hyd cam std cast iron headers 232hp at wheels.currently doing sr20turbo in toyota ute.WB 308 ute.fully worked VN commodore 355 stroker.were in perth street car mag the latest and the last.i know there fords but they,v still got 8 cylinders.

hi tyson
i am interested in a performance lpg(injection) application for my RB30ET
wouldn't mind a chat
can i call you or better still drop into your workshop
curious,is your injection system vapour or liquid?,what HP can each injector support,can i run my exhisting EMS(wold 3d)?

Gday Tyson
I have a Hornet with the AMC high compression 360 engine 10:1 and have been following your Perth Street Car Articles. I plan on using this lpg injection setup as soon as I get financial for it. Ideally I would like a twin turbo, centrifugal or belt driven blower all under hood with 3/4 of a bug catcher out of the bonnet. Firstly, Given that manifolds are hard to get a hold of in Australia, Is this setup retrofitted to the existing manifold??? Second, What dollar figures have your previous similar projects come to?. Obviously without forced induction costs! Third, what waiting periods am I in for. Where are you in Perth??





this is Tyson.our lpg system is straight lpg no petrol as i dont like petrol at all.its fully programmable timing pulse width, boost retard ,thermo fan idle, controll etc.the rb 20 punched out 240hp at the wheels at motorvation with 10 lbs of boost at 6500rpm these things go to 7500 an was runnig bit lean so more gas more kilowatts.i can retro fit to any aluminium manifold but having a look is always the best bet for me.prices vary.i just finished playing with an AMC those things rev hard any forced induction will work great.this guys got heaps of AMC parts manifolds just moving my workshop to number is 0409140226

Hey, I work at a lpg installer in the Bayswater, Vic area and we have gas injected many many many cars and I thought I would clear some stuff up. First, direct injection relates to fuel being injected in the combustion chamber. what you are looking at is vapour injection.

There are a few brands floating around the market lately, as it is being rushed into the market over the past few years. I wouldn't fit anything but Impco's BRC, Vic Auto Gas's Tartarini, or SprintGas's OMVL. The procedure is the same in the rear of the car with cylinder mounting and lines and it all flows forward to a gas regulator at the front of the car. the regulator flows vapour through a 1/2" pipe, through a finlet and into an injector rail or four, controlled by the gas ecu, piggy backing off the petrol ecu. the gas flows through injectors and into 3/16"ish (different systems use different sizes) hoses with a barb fitting drilled and tapped into your inlet manifold. on an already injected car it is an affordable option but its around the $4000 mark.

for a carby fed car, it takes a little more. you dont have a petrol ecu to rely on for an injector signal, or for cold starting. although this is overcomable. we have gas injected a 34 f*@d roadster (bosses car) with BRC injectors and reg and a halteck ecu and power increase was massive. we are still looking for oppertunitys to fine tune the car between all the work we have on and I am trying hard to get him onto a 1/4 mile. the straight gas injection systems can cost real big, $5000 and up doing it cheaply.. the main cost being ecu as an aftermarket petrol ecu needs to be used or an even more expencive aftermarket gas ecu ($4000 for ecu alone).

If you want to spend that kinda dosh on your car, I'd be happy to do the job for you, but I'd probably recomend a redline manifold and some gas research or some good ol' impco dual fuel.

I will be gas injecting my mini panel van after the body work is done. its great technology and works real well.

Rat Man: I have done supercharged cars too and they go great :)

Tyson, mate tried to ring a number of times but no answer can you confirm your number and shop address, need you to throw an eye over my Rambler and start the brainstorm. Cheers. Jardin.

this is Tyson my number is 0409140226 i live in the hills so reception is bad sometimes. Were not going to malaga we are going to midvale 11 runyon rd just outside midland we,ll b setting up there from may the 2nd.

this is Tyson from RAGE LPG.Vapour injection works on any vehicle an works great we see alot of power increases escpecially through the lower part of the rev range great torque increase.Our ECU,s are specially designed to run LPG vapour injectors and is designed an made in W,A has a lifetime warrantie an cost $1000.We try to flow the vapour directly at the valve head we use the best we could find stainless keihn injectors that flow 4700cc (about 600hp for set of 8)of lpg and prins converters that will flow up to 450hp each.all our set ups use custom fuel rails speedflow fittings and are custom wired into the car there is alot of work involved modifying the manifold depending on the model to accept the injecters to make the whole lot look hot and factory plus fitting manchester tank lines converters plus alot more etc .We dyno the car b4 and after for the best results we can get.For example an AU v8 will cost u $5000 straight lpg fitted drive in an out(we offer ongoing support for any upgrades to the car cam change nitrous boost etc we just put NOS on an old 66 XP 302 STRAIGHT LPG and that lights up great) depending on part prices as they sometimes vary we only use the best parts available under bonnet components have a 2 year or 40,000km warrantie.We do dual fuel now as well due to high demand boats an turbo deisles.An older retro car v8 from rods to WB,s will cost around $5500 up wards depending on horsepower levels wanted.Fully fitted drive in dynoed and drive out.WE,LL LPG ANYTHING.

R.A.G.E LPG Racings address is 11 RUNYON RD MIDVALE we,ll b there from the 10th of may ph 0409140226 or 0417086773.

Thanks for the info Tyson.

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Tyson, you got a website? I would love to see some of the stuff you are spitting out. you sound like you take some pride in your work, I like that :)

Hi mate. Just wondering about Direct injection for a VZ Clubsport. I just about to commit to getting a Sprintgas direct Injection setup put into the car with a donut tank. Am getting charged just over $5000. The money isnt too much of an issue, but I'm wondering if the sytem you use is better for keeping the performance up to scratch and what you would charge. Cheers mate

Hi,Igot my monaro fitted at Autogas connection and it runs like a charm.On the Dyno the power peaked just a smidge more than the high octane v power pulp.187 rwkw.
currently all else is stock.

Dose anyone know who has the highest octane lpg?

LPG is a mixture of Propane and Butane. The amount of Propane can range from 100% down to 50% (i.e 50/50 Propane/Butane).

Commercial Propane has a Research Octane Number (RON) of 100 and a Motor Octane Number (MON) of 97.

Commercial Butane has a Research Octane Number (RON) of 92 and a Motor Octane Number (MON) of 89.

LPG sold by:

Caltex: RON = 100.

Shell: MON = 92 minimum.

BP: MON = 93, RON = 100.


Hi, dunno if this is the right place for this question but my ba backfired today and popped the air box off now it will not run on gas at all it is dual fuel and runs on petrol nice everything else is completly normal but will just keep stalling on lpg!!!

Any help would be great....

Hi, its possible you may have damaged the diaphram in the gas mixer. a backfire sends huge reverse pressures into the intake, through the gas mixer and back to the air box. usually when the system is installed, a blow out plug or sleeve or similar is fitted in/on the air intake between the gas mixer and the manifold, so that if/when the gas backfires, the reverse pressure is dissipated out thru the plug etc, rather than backwards thru the gas carb. Check the air duct/intake to make sure it is all still in the right place, if the air intake is dislodged etc, then u have a gas leak and it will run lean and wont idle. if there are no plugs/leaks/ or anything else wrong with the system, its more than likely you may need to replace/fix your gas mixer - they are not designed to take the full impact of a backfire, which is why most fitters will fit a backfire plug etc...

Hi, can anyone answer a few questions i have:
Im installing a toyota SC14 supercharger onto my worked LPG 202. The motor already has 9.8:1 compression, lots of head work and cam etc etc etc. Im using a slightly modified VK efi manifold. I have been looking at draw thru and blow thru systems and have found that while it is possible (a few people have done it) to blow thru both impco and gas research gas mixers, it is not recommended. I am only looking at about 5 psi boost, so not heaps, but need to find a gas system that will work well under positive pressure, plus try to limit backfires. I know that draw thru systems are prone to (very expensive) backfires, as the supercharger and all intake lines would be full of gas - resulting in blown up blowers from a single backfire!
I have deduced that possibly two impco 200 series mixers mounted side by side, fed by 2 model L impco converters might work in a blow thru config, although im now looking at the possibility of vapour injection.

Can anyone give me some info on whats involved in setting up a vapour injection system on a holden 202, straight gas but using an EFI manifold, plus a blower running approx 5psi? Also how much a vapour sytem like this might cost?
Some say it can be done, others say it cant. I know some vapour systems rely on starting the car on petrol to warm it up, then switch automatically to gas so the injectors dont freeze up on cold starts... is this a problem on straight LPG cars?
What happens with computers etc on a car pre-computer? Can any EFI computer be modified to work with the vapour injection?

Any info would be great!


Hi, I have been running an SC14 (no clutch) blow through setup with a gas research carb bolted to a VK EFI manifold (in place of the standard EFI throttle body). The main problem with the blow through is that when the throttle is snapped closed (e.g. when changing gears at high RPM), the pressure between the blower and closed throttle body causes the blower to want to stop spinning. This turns the V-belt drive to liquorice in no time. To run this setup, you will need either/or combination of a BOV (between blower and carb) or clutch (like original SC14 design). I have experimented with the BOV and found it to work exceptionally well. Unfortunately, running a BOV in this location will increase the induction noise on deceleration. i.e. Like a turbo you get the "pssst" noise. Unlike a turbo you get the "pssst" noise constantly when off the throttle. Very, very loud. Even when rerouted back into the induction tubing. Louder in fact on deceleration than acceleration. Very, very fast. Very, very bad Zen(NVH). Another issue with the reroute to the front of the blower is superheated induction temps causing the teflon on the rotors to cook. I could have rerouted out the exhaust but have decided to go turbo now. Strata exhaust, blow through gas research carb. That's another story....

Yeah I might have guessed that because the blower is pumping air all the time your BOV is pssst-ing whenever the throttle is shut and the revs are high.
So have you had any problems with blowing thru your gas research carb? What converter/s to you run? Do you have any problems with leaning out at high revs or anything?
Iv heard problems with blown systems tending to blow the gas back into the converter and therefore running lean under higher boost. Normally the converter relies on engine vacuum to draw the gas thru, does this need to be overcome by using a different converter or different diaphram springs? Is an impco model L ok?

Anyone one with more info, would be fantastic!


The converter must be balanced (or biased) with a sample of the boost pressure.

This maintains a constant differential pressure between the output of the converter and the boost pressure.

In a normally aspirated setup, the final stage diaphragm in the converter is balanced to atmospheric pressure (or close to it), so the output of the converter will be about -0.05 psi below atmospheric pressure.

In a forced induction setup, the "atmosphere" side of the diaphragm is connected to the output of the blower/turbo. So, assuming 5 psi boost, the output pressure of the converter will be 4.95 psi above atmosphere.

Impco model L converters are rated at 5 psi max boost.


So thats as easy as connecting the bottom vent outlet in the impco model L to the manifold?
Will this still work if im using a bypass valve and a clutch pulley so the blower turns off at low revs/load when not needed? The motor then turns into a N/A engine. Will the converter still work if it now sees engine vacuum instead of boost?

Are there any other options to using the impco system under forced induction? ie a model L converter and 200 series mixer..?


Hi, i'm currently building a 48 chev stylemaster hotrod. I plan to put a nice 383 stoker in her, 195cc AFR heads and a hurrican performance manifold. But since she will proberbly be driven daily i'm thinking about ecconomy, and gas seems to be the go. The last few months i've been studying up on different gas systems. And i think i will run it on straight gas through a gas research throttle body but the problem i have is really cosmetic, as i will be showing her at meets, shows and so on i wont it to look traditional under the hood. Gas research throttle bodies look good but they dont sit under a nice chrome air cleaner. The other option i have explored are gas injectors, but i wont have an existing OEM to run the injectors off. Thus creating my first problem with injectors, also injectors take away the look i'm after alltogether. So i want traditional looks, as much as 400 horsepower and some sort of ecconomy.
Can any one help me with some ideas.

G'day Mate - Technocarb is the most trad looking gas throttlebody - looks like a billet four barrel - because it is. All you've got to do is hide the mixer, which I've done down behind the radiator - or if you're really determined, it MIGHT fit directly behind the carb under a twin four barrel air cleaner - with a lot of work.
I'm having a bit of grief with Technocarb here though - check out the thread.
Good luck with the project!

R.A.G.E.LPG Racing in perth do hi performance dedicated vapour injection and custom make there own billet 4 barrel throttle bodys that flow some good numbers i think 750+cfm they run 2 converters they tune them on there dyno for best economy and max power a bit like the barry grant carbys with sleeves a freind of mine had his 351 f100 done there he had an impco 300 duel fuel setup on it then they put the billet mixer on it turning it into dedicated he said power was way up an his econmy was awsum he would get 2 trips from midland to carousel and back with impco, with billet mixer he got 4 trips.there injection theyv got this dodge challenger in there 16 gas injectors big 1000hp turbo 440 motor he reckons looks sick they,ll be dynoing that soon apparently.

hi guys i have a 350 chev motor what is the best straight gas system that i can put on (is a duel gas research system best for me(i am in melbourne ) for best results and preformance can someone direct me to a place? and what $$$$ am i looking at

thanks jake

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