A quick question can a standard mixer LPG setup (on dual fuel car) be used with forced induction (supercharger or turbo). I know multipoint injection LPG setup can definitely be used for those.

Suckthrough - yes on unintercooled setups. On an intercooled setup its a big no-no, not because the fuel will condense, but because there is a lot of volume of fuel/air mix for a backfire to ignite.

Someone did a CAPA ute with gas IIRC. Suckthrough setup, unintercooled.

I have certainly seen standard mixture LPG and turbo but NOT dual fuel using either standard or lpg gas research carb. This is the emissions legal way of turboing pugeot 505 V6 on aussiefrogs.com

That site will guide you to and lpg only method.

Suckthrough - yes on unintercooled setups. On an intercooled setup its a big no-no, not because the fuel will condense, but because there is a lot of volume of fuel/air mix for a backfire to ignite.

Someone did a CAPA ute with gas IIRC. Suckthrough setup, unintercooled.

So no intercooler ah, that means turbo is definately not an option. Some supercharges you can run up 10psi with no intercooler (mainly centrefugal), are there any boost limitations with mixer LPG set up?

The reason why no intercooler is simple - you have a large volume highly combustible mixture in a semi-enclosed container - add an ignition source, and you have yourself a bomb. Scary.

Running forced induction unintercooled is a product of adibiatic efficiency (how efficiently the compressor does its job) compression ratios, carbon deposits, ignition advance, whether water injection is run, outside temperature, phase of the moon etc.

The only complication is the ignition advance you need for LPG is the exact opposite of what you need for forced induction.

Do you want to do this to a Magna?

Suckthrough - yes on unintercooled setups. On an intercooled setup its a big no-no, not because the fuel will condense, but because there is a lot of volume of fuel/air mix for a backfire to ignite.

Someone did a CAPA ute with gas IIRC. Suckthrough setup, unintercooled.


How much is this going to cost the OP?

The reason I'm asking is if this is something that's going to run into the $6 - $7k bracket, wouldn't it be easier/ cheaper to have all 'under the hood' parts of the LPG system replaced with an injection system?

I was quoted $2-$2.5k to have it all replaced in my TL. It's surely a cheaper/ quicker method of acquiring some real gains for the car? Then you have more options to explore for supercharging at a later stage. Plus all gains are genuine gains whereas with the mixer system all gains are as stated less the % loss that is accompanied with this type of system.

Dude,
I have a blow-through turbo lpg setup on my car :D. My car is working proof that this concept is not only workable, but can handle much more than the 10psi boost that I am running. I have an intercooler which is not filled up with gas or anything like that, as I have the gas mixer mounted right in front of the throttle body. Turbo or supercharged LPG means that you do not have to buy any expensive fuel management systems, saving you money I guess. You can ask me heaps of questions about it if you want :) I will try to find and send some pics or even post a youtube video :)

Shagna

Blow through will work? I didn't think the mixers were capable of this! Interesting. All I have seen is suck through systems. What mixer are you using?

LPG would be a shyteload cheaper than paying for the fuel for the very thirsty sprintex setup.

Blow through will work? I didn't think the mixers were capable of this! Interesting. All I have seen is suck through systems. What mixer are you using?

LPG would be a shyteload cheaper than paying for the fuel for the very thirsty sprintex setup.

Sprintex is a whole different kettle of fish. On Shagnas turbo setup - hes mixer is along way after he compressor, mounted right before the T/B. On a sprintex setup, where the compressor is after the throttlebody - you don't really have an option of putting the mixer after the compressor, unless you go direct LPG injection. Thats really the only way you can I can see of running LPG with Sprintex blower setup on a magna.

Dude,
I have a blow-through turbo lpg setup on my car
Shagna

So at 10 PSI you had no problems? I can understand a turbo concept (& how spupercharger setup might be difficult to accomplish because of where its located after the TB), my mixer right infront of my TB anyhow (at least thats what ive been told). What about tuning, who & how would that be done. Oh yea if you got time some pics would be awesome.

I have been quoted 3gs to make my car multipoit injection LPG, if i can get away with leaving my current mixer setup that would be great.

I have spent way past 7gs on my car already, unfortunately nothing really on perfomance, exept by quad tips :) & k&n panel filter. So im really keen to go ahead with it.

After doing some research I really don’t understand why blow through on LPG with intercooler is not suitable option?

I would think blow through design will be more beneficial to LPG with mixer set up.

Picture this

Turbo compressor is placed right after the air filter; followed by an intercooler, then compressed air (under boost) goes past the LPG mixer which is placed right before the throttle body. Then LPG/air mixture goes into the cylinder for the ignition. The benefits I can see (like mentioned previously) is the absence of expensive fuel management systems, no need for bigger injectors(since its an LPG mixer); LPG setups are fully tunable I don’t see a need for a piggy back either.

And from shagna’s experience with 10 PSI boost I don’t see any problems with such set up?

Am I wrong?

Yeah, but notice I said suck through systems.

Was having a brain freeze with sprintex and blow through - I was upgrading firmware on codecs so my mind was elsewhere.

Time to take photo's...

Oki doki. This is a work in progress requiring editing so bear with me if you are reading this...

The first photo got into my batch conversion on accident. I thought I wouldn't remove it now. It is of my work mate at our head office in Brisbane

2nd photo is an overview of the engine bay showing a lot of changes involved with turbo and lpg. Lots of hoses and pipes and stuff.

3rd photo shows a lack of wiring onto the fuel injectors meaning that this is a dedicated LPG setup. If I was to run the turbo with petrol, it would run very lean after about 2psi boost, which is when the stock fuel delivery system maxes out with the stock engine management, so dedicated LPG means I can't do that as there is no petrol.

4th photo shows a plumb back fitted. A blow off valve can be used if it operates just like a plumb back, which to my knowledge most of them do. The gas converter cannot be allowed to respond to the surging pressure from the compressor wheel if no pressure relief is fitted. If there is no plumb back or blow off, the surging will force the diaghram in the gas converter to move in from out fluctuating the fuel deliver from lean to stoich to lean to stoich to lean as long as there is surging between compressor to throttle body. However, once neutralised all is normal.

2nd lot of photos

1st photo shows the converter. Notice the pipe on the front of the converter. Without the pipe there is a little hole so the converter gets a reference of the ambient air pressure for natually aspirated engines. In this case the pipe is connected somewhere between the compressor and the throttle body. It can be mounted with the 'main diaghram balance pipe' (refer to 2nd and 3rd photo) but in my case it is mounted after the compressor and before the intercooler. There is a little more boost here then elsewhere in the the intake system and it is ok in this case. The purpose for this pipe is to increase the gas pressure not flow. Great for when the converter is fighting over the boost provided by the turbocharger.

2nd and 3rd photos show the main diaghram balance pipe. This pipe is the main pipe to determine whether your car is boosted or not. Normally the air flowing though the 'carburettor' style gas mixer creates a slight vacuum force on the front of a diaghram. When you boost this diaghram is pushed the other way shutting off fuel delivery. The balance pipe brings air pressure to the back of the diaghram returning it to the normal position. The venturi effect created by the gas mixer still creates a slightly lower pressure region on the front of the diaghram, the same as natually aspirated systems. This pipe needs to be located as close as possible for the diagram to operate correctly.

4th photo shows the 'powervalve'. In normal conditions, this has an electronic valve controlled by a computer which monitors oxygen sensor readings and basic throttle position readings. This device maintains a stoichometric air fuel ratio by constantly adjusting the flow of gas vapour fed into the gas mixer and in turn, the engine - just like todays petrol engine management systems. This is needed if you convert your EFI car to LPG but not if it is carburetted.

3rd batch of photos plus youtube video

1st photo shows the location of the gas converter, the vapour line into the mixer and its location infront of the throttle body. The shorter the vapour line the better. Especially for dedicated LPG setup. Dual fuel setups usuall start on petrol first and then switch over to gas. So the shot vapour line and close proximity of the mixer to the throttle body helps with starting and also provides the best performance for the engine.

2nd photo is just an overview of the entire setup.

3rd photo is proof of an intercooler being used in this turbo lpg setup.

4th photo shows the back of my car. I thought I wouldn't leave it out - note lpg on number plate :)

Youtube video:

EDIT: youtube thread for videos!!

Sorry about the youtube video people :( at least its kind of informative

Please excuse the youtube video for me being a bit of an idiot. There is one area where I call the gas converter a 'mixer'. I am confused and hungry so maybe I will make another video with my friend that helped me install and tune the system.

In regards to tuning, there is little difference compared to a natually aspirated car. There are the aformentioned extra pressure lines but the rest can be tuned just like an N/A LPG car. It's so easy that I did the tuning myself down the street, albeit with some intruction. Lets have a look...
Idle screw: adjusts the amount of fuel delivery for idle. Sets up a 'base map' for the sensitivity screw. Any adjustment to sensitivity may result in an adjustment required for idle

Sensitivity screw: like a 'fuel curve' this will 'map' the the diaghrams sensitivity across the whole range of air pressure going into the engine. It is remarkably simple to achieve a nice 'fuel curve'. Any adjustments to the idle screw will upset the sensitivity and will need adjustment.

Powervalve main flow screw: Adjusts the maximum amount of gas to be delivered under full throttle and high rpm conditions. Has a small effect on the amount of gas delivered under light engine loads.

FP31 Gastek LPG & CNG Microprosessor: has an adjustment for the idle throttle position adjustment. This forces the powervalve to remain fully open in idle conditions running the engine slightly richer than stoich. Perfect for cold engines and provides a reliable idle. The FP31 can understand when the driver puts the pedal to the metal, as it will fully open up the powervalve for maximum fuel and when the druver returns to normal, will go into 'closed loop' fuel monitoring as previously described for maximum efficiency.

Well that will do for now. I hope this helps for any curious LPG people out there. For turbocharged systems the modern gas converters and microprosessors can handle the boost really well and most people would have no idea that the car was on LPG.

LPG often has negative effects on N/A cars maximum power and effeciency. This is less noticeable in turbocharged cars. Let me explain why.
Benefits for why LPG is good for boosted cars...

1. You can advance the timing. If it is a dedicated LPG system with or without a turbocharger, the timing can be advanced to take advantage of the higher 'octane' this makes the vehicle much more efficient and have a noticeable difference in max power and torque. This is ofcourse if the vehicles timing can be adjusted eg. distributor, crank angle sensor, aftermarket engine management etc...

2. It's boosted! The gas mixer on an N/A engine restricts the air going into the motor at high rpm at wide open throttle maybe up to a couple of inchs of vacuum on a boost gauge. Being boosted the engine will run at the specified boost regardless of what restriction in the intake as the max boost will be governed by the wastegate.

3. I forget but there is one. I will edit this post when I remember.

Thanks so much for such detailed info. I’m so convinced now to do ahead with it. I’m actually looking for some turbos at the moment, might go with Garrett gt25 since RPW has manifolds & dump pipes for sale thus making it easier to install a turbo.

One last question I have, is your LPG equipment besides the extra pressure lines, is all standard. I had my car converted about 6 months ago just wondering if I need to change anything. Does it take any “performance” type of a converter to deliver stable vapor enough for 10 PSI boost?

Great Vid was interesting to watch do you know how many awkw your car makes

The article here may have some figures?

http://autospeed.com/cms/article.html?&A=2367

EDIT: No it doesnt :( but its a good read, even though Ive read it about 20 times over the years.

Doesn't LPG have a significantly lower calorific value compared to petrol? Seems like you'd be losing a ton of power by having an LPG install rather than petrol.

Also is it dedicated LPG? Engine management must go crazy with dual fuel.

Doesn't LPG have a significantly lower calorific value compared to petrol? Seems like you'd be losing a ton of power by having an LPG install rather than petrol.

Also is it dedicated LPG? Engine management must go crazy with dual fuel.

Lower yes, tons NO.... only barely noticiable diffence is at high rpms only but as was expalined before boost will improve that... Even in LPG mode VT commodore stands no chance agains my TJ, tested over & over again :). Look on VT driver's face priceless....

Ah yes, I remember that day. Notice in the article the secondary fuel rail. Silly setup it was with the fuel management that I had. Interesting digg. My engine bay looks a bit different now.

LPG does have a lower calorific value but in a dedicated setup or boosted setup the difference is not very noticeable, if at all. A few posts ago I mentioned about how it gets improved. I should get my car on a dyno because it would be interesting to see what power it has.

Italian made 'Airod' gas converters are great. That's what I have. The small pressure line on the front of the converter increases the pressure heaps turning a lower flowing converter into a higher flowing converter by increasing the gas pressure - just like a malpassi rising rate fpr. Check to see if you have a hole here and if you do, PERFECT. A pipe will be connected there. There should be a hole on the rear plate which is for RAM air intake systems and in my case a turbocharged system. Accordin to the converter, I just have a hardcore ram air intake system, so if you see a hole (maybe with a thread) PERFECT. Other modern converters based on the same principle of how it works, which I beleive most are, would be able to work. I was showing a work mate who owns a TH wagon with dual fuel. His converter was not an Airod one but it had the capabilities for the correct lines to be fitted. So he and possibly you could get blown and spend zero dollars on aftermarket fuel computer!

BTW

Thanks so much for such detailed info. I’m so convinced now to do ahead with it. I’m actually looking for some turbos at the moment, might go with Garrett gt25 since RPW has manifolds & dump pipes for sale thus making it easier to install a turbo
Thats crazy :D as in awesome crazy shiz!!!

Doesn't LPG have a significantly lower calorific value compared to petrol? Seems like you'd be losing a ton of power by having an LPG install rather than petrol.



I think it's actually more to do with the octane rating of LPG, which as you may or may not be aware is much much higher than even the highest octane pump petrol you can buy.

So you end up with a extremely high octane rating fuel source in an engine designed to run crappy regular unleaded - so of course it isn't going to realise its full potential. Hence why people who do LPG conversions on regular petrol engines loose some power. Rebuild the engine with say 15:1 compression (11 or 12:1 for turbo) however and it would be a different story.

Hell yeah!

Also, something I forgot to mention:

It is also possible - in low boost setups, that no management is needed to control ignition timing under boost conditions. This is because of the awesome anti-pinging properties of LPG. Otherwise MSD ignition products make a few nifty modules that not only increase the spark output but also retard ignition timing under boost. Perfect as LPG likes a little extra oomph in the spark. Something I would like instead of my Link piggyback ECU :)