Blowthrough propane fuel system

[defrag010]

As I've mentioned before, I'm in the planning stage for building up a moster VH to sit on a stand for now and replace the stock VH in my rx7 when it blows up. It's going to be completely forged, 4" bore, offset grind on crank for about 5.4L, and have alot of headwork done including 3mm over exhaust and 2mm over intake valves along with delta regrind cams and some mean springs. Basically, I'm sticking two GM-8 turbos on and going all out on it and building it specifically for propane (about 11:1 compression due to milled heads and flat top pistons).

Thus, I've decided to run the car on propane. I've already researched and picked out the right components that I need for my horsepower goals, but I haven't really been able to find the answers to a few simple questions. I have read that LPG performance is a little bigger down under than it is here, so this is the only place I knew of where there are alot of aussies that know about this stuff.

-Can you take a downdraft mixer (like an impco 425) and run it side draft? I'd assume so, since the propane is already a vaopr once it gets to the mixer.

-Does the fuel consistancy change with tank pressure? ex. - will I have to top off every few miles to stay on tune, or will I be able to run the same tune at high power levels until the tank is empty?
Modified by defrag010 at 5:35 PM 11/6/2006

[elwesso]

not really on topic, but i didnt know you had a VH in an RX... where/when did you post info about this?

[defrag010]

I posted about it a buttload of times before and just after we got the VH subforum.. I guess everyone payed more attention to the other swaps or something.

It's not 100% done, as I still have to find a T56 and make an adapter, but I have my mounts done.

[elwesso]

oh ok, i was thinking you were done, but its not running yet...

[Mettler]

Good stuff defrag, this is the first I've heard of it too, and I'm sure I've read pretty much every thread in this subforum. I don't read any other parts of Nico though, that may be why I haven't read about it.

You should start a dedicated thread about your project car so that we can check out your updates, I'm interested in seeing your progress!

[defrag010]

thanks! It's not progress thread worthy yet, though, cause I'm doing a Vortec 4.3 ---> 280ZX swap right now and I'm not going to start on the rx7 till after that. I decided to go all out on the rx7 instead of just throwing the VH in there like I had planned originally. I also bought a M30 to put a stock vh45 in too, so I have quite the stable of incomplete swaps right now.. on Top of being a fulltime college student!!! lol

Here are a few pics of the rolling chassis when I got it cleaned up. It will look the same, only it will have widebody fenders (bought this week).

[maxnix]

Why propane? Less BTU per unit volume.

Seems like you have more that enough on your plate now. Keep it simple and you might finish one!

[Nyloc]

1. To the best of my knowledge you can mount the LPG mixer whichever way you want.

2. The system runs a regulator, you get consistent fuel delivery right up until the last drop.

3. Trying to convert the older mixer system to blowthrough might have a few pitfalls, since it keeps the lpg pressure at a finely balanced level fractionally above atmospheric and allows the gas into the intake stream via a venturi lifting a plate. Suckthru, and running the fuel thru the turbos would be easier, or the newer electronic LPG injection systems.

4. If youre going for power this system would be harder to tune for reliability, despite the higher octane. As Maxnix says you loose a lot of energy with LPG, the higher compression ratios possible due to higher octane only barely negate that. It can and will still detonate in the cylinder. Accurate fuel delivery over the rev range at the ratio required will be difficult.

5. look up the eng-tips forums, the automotive fuel and engineering section, and have a search. Theres some very knowledgable people there who have answered a lot of propane related questions.

[defrag010]

Nyloc... Thanks!!!!!

I've posted this on a few other forums, and the guys on speedtalk say that running blowthrough will be alright as long as I give the converter a boost reference. I was originally going to do draw-through, but I keep hearing about backfires.. and I don't want my intake plumbing to blow up! Are backfires very common?

the reason I want to go with propane is because I am absolutely sick of the differences in pump gas consistancy where I live. One week, the gas is awesome.. next week, the same gas from the same pump will ping like a mofo, etc. I've tuned alot of pump gas turbo cars (dsm's, a few hondas) and I don't want to always have to worry about bad gas. Plus, propane is alot cheaper than gas too and there is a u-haul refill station about a block from my house. I'm aware of the lower BTU vs. gas, and that's why I am putting the turbos on!

[Nyloc]

Backfires can happen while starting. I've only managed to get a backfire while cranking and opening the throttle overly wide at the same time, with the lp gas powered vehicles ive owned. One was multipoint injected with a flap type AFM, it would simply blow the intake hose off at one end when it backfired. Backfires happen about twice a year on average, with a daily driver. Normally a backfire will result in a decent bang. With suckthru it wil be huge! Specially if you have intercooler plumbing, there will be a nice big volume of gas. Maybe not a good idea.

[defrag010]

Okay whew, i didnt know if it was a common thing or not. That doesn't sound too bad cause I'm not going to be daily driving this car that much. Would there be a way to setup my intake system after the mixer to where it would just come apart by design rather than grenading my turbos or messing stuff up? like a rubber coupler somewhere or a blowoff valve as a failsafe?

Also, if I was going to do draw through, would I just revert to the carb size that my engine would regularly use n/a?

Do you think an IHI GM-8 turbo has the right kind of seals to be run in drawthrough?
Modified by defrag010 at 12:55 PM 11/9/2006

[Ezekial]

never saw any posts about your car either mate!!

link??

dont know if this helps any??http://home.iprimus.com.au/pro...l.htm

Twin Turbo LPG VH45DE 550hp @ 15psi

[defrag010]

WOW, that is Exactly what I want to do only I want to use two tanks and two converters/mixers with my custom intake mani.

Is there any more info on his setup?

[Ezekial]

send him an email mate ... or give him a call ... 7 hours behind + 1 day ahead

or if you tell me some questions you want answered I'll be happy to call him for you

[Nyloc]

never saw any posts about your car either mate!!

link??

dont know if this helps any??http://home.iprimus.com.au/pro...l.htm

Twin Turbo LPG VH45DE 550hp @ 15psi

That is just awesome! I like... alot.

And a much better source of answers for defrag.

[muchilus]

it's very weird to heard someone in US try to use LPG. But let me introduce my self, i'm living in D.R. (Dominican Republic) here is better often to use LPG as a alternative fuel, by obviously first by price 3 gallons of lpg by the price of one premiun unleaded gasoline, second benefits to the engine, third is a green fuel , and less pollutions , around 35-65% less that gasoline.

but the reason why i answer you this question is because already own a infiniti fx35 2005 with LPG installed, but not with a mixer as you think is with a full sequential injection system. the system works identical as the same principle of Gasoline, use ECU apart, that controls all the additional parameters and device, like injectors (LPG), MAP sensor (LPG), release valves, Selenoids.the vehicle always start in gasoline, and change automatically to LPG after you pass the 1,600rpm even if you get empty of LPG you cross automatically to gasoline, has a level information unit, also you can change manually what ever you want to use any of both fuels. also i had a Toroidal Tank, that is almost identical to spare tire, and can fit in the most of the trunks.

Benefits from the system:

-keep your horsepower and acceleration by a fraction of the gasoline cost.-keep your engine clean of carbon, because burn 100% doesn't leave residue in the cylinder chamber, so not contamination to the oil, spark plugs and catalytic converter.-GREEN FUEL -cheaper-Pure Italian Technology.

If you need further details just let me know .

Regards,

Carlos A. [email protected] My msn.

[hannibal]

You guys rock!

Ive heard of propane injection, but never running completely on propane...

[T45]

The shipyard I used to work at had a nissan 4 banger LPG forklift. I tried to take it when I left but it wouldn't fit in the civic.

[muchilus]

also , i have my Infiniti fx 35 very hook up!

Tartarini Sequential System LPGStillen Cat-Back ExhaustStillen HeadersStillen Cold intake airUndernox underdrive pulleyHigh Flow Catalytic Converteraround 42hp to wheels additional to reach 326hp (the same of fx 45), and much better running on lpg. i'm doing the drag time in 1/4 mile in 15.3 Seconds, in both fuels. Petrol and Propane.

[muchilus]

the system works perfectly in 3-4-5-6-8 cylinder vehicles.

how i can insert a picture here!? i've trying with the icon "insert image" but doesn't work

[muchilus]

If you want to get better performance that petrol and archive your goal, try out with the Tartarini Sequential System.

Regards,

[Raxephon]

how i can insert a picture here!?

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