LPG with forced induction.

engmpoll · Post by **engmpoll** » Wed Jul 30, 2008 7:34 pm

Anyone here running LPG with some form of forced induction? either supercharged or turbo? What setup are you using, lpg sequential injection or the good old fashioned venturi mixers? and finally suck through or blow through. Also anyone with any thoughts on this please have your say!!

Thanks in advance!!

v8man · Post by **v8man** » Wed Jul 30, 2008 8:02 pm

not a v8 but seen a lot of porsches 911 turbo on lpg in London

camel1 · Post by **camel1** » Fri Aug 08, 2008 10:05 pm

[/img]
Thats my wade ro34 on a 3.9 rover
LPG only use,in IMPCO equipment a Model E regulator and a 425 Carb draw through
The carb fits onto a holley 4 barrel throttle plate and can be mounted at any angle! With MSD ignition with boost retard it runs very well.
The belt has now been changed to a single multi vee.

engmpoll · Post by **engmpoll** » Tue Oct 21, 2008 2:24 pm

camel1

I'm trying to get my head around the function of the carb??!! I assume its just used for the butterfly in it to control the air flow. Am I right? Also your set up as draw through, does lpg suffer the same problems as petrol with draw through setups or is the fact it is gas when going through the charger solve this problem.??

chodjinn · Post by **chodjinn** » Tue Oct 21, 2008 2:48 pm

well the carb would be to get the LPG stuff in surely?

And what do you mean 'suffer the same problems as petrol' on a draw thru system? The fuel will act as a coolant in a draw thru configuration, which is a benefit, not sure about LPG though (I'm assuming it will have a similar effect?)

engmpoll · Post by **engmpoll** » Tue Oct 21, 2008 4:21 pm

The lpg wont be plumbed into the carb direct it would have to enter the engine as a liquid then. The lpg will be plumbed in via a vapouriser which feeds a mixer mounted to the inlet of the carb. Then when you open the throttle the butterfly will open in the carb and more air will be drawn in causing a vacuum in the mixer and pulling the lpg into the engine.

With regards to draw through systems, I was led to believe with petrol as it enters the turbo/supercharger it is spun to the outside of the turbo/supercharger by the effects of centrifuge and therefore the mix is weak entering the engine. Thats why blow through is more preferred?? Whether this is the same with lpg as it is already in a gaseous state prior to entering the turbo/supercharger I don't know.

chodjinn · Post by **chodjinn** » Tue Oct 21, 2008 5:16 pm

well you seem to understand why the carb is there, so why ask?!

As for suck thru, i'm sure centrifugal forces do come into affect, but plenty of people run them will silly amounts of power without issues. I used to run 250bhp through 2 HIF carbs sucked thru twin turbos, until the engine went bang lol

engmpoll · Post by **engmpoll** » Tue Oct 21, 2008 6:08 pm

Your right, kinda answered my own question.

I read about this issue with draw through when gsxr1100's were having mr.turbo kits bolted to them left, right and centre. I would imagine your limited on the boost side of things due to not having the ability to fit an intercooler.

I found this website,

http://www.go-lpg.co.uk/Turbo.html

is anyone buying this? It sounds a bit like scare mongering, I don't doubt that it could happen but this website seems to force the point a bit 'you need an expensive sequential injection system to run with forced induction' etc etc.

chodjinn · Post by **chodjinn** » Tue Oct 21, 2008 7:45 pm

Quite simply, bullcr@p IMO.

How many top fuel dragsters etc. run suck through systems? Plenty.

If any doubt, check out Barry Grant, one of the best tuners for twin turbo V8s in the states. He has repeatedly ran suck-thru kits for chevys etc without intercooling for decades for motors pushing 600/800/1000bhp+, so it can be done without issues.

Maybe the motorbike/website thing came a problem due to such small inlet manifolds, which may exaccerbate such an issue as mixing? Dunno, pure speculation. To be honest i don't see it being a problem on a V8. Get it done mate!

Post by **katanaman** » Tue Oct 21, 2008 8:24 pm

That page is on about LPG. Going by some of the posts in here it can and frequently does go bang in the wrong places. Not saying sequential is the only answer just LPG has more of a tendency to backfire and could potentially do what he is describing all be it he is a bit extreme.

engmpoll · Post by **engmpoll** » Tue Oct 21, 2008 8:25 pm

Bull, exactly what I was thinking!! They just want idiots to buy there expensive injection systems!!

Right lets get cracking!!!

camel1 · Post by **camel1** » Wed Oct 22, 2008 10:44 pm

Well that picture seems to have got a few heads scrat,in

First off.
The carb is an IMPCO 425 this bolts onto a holley throttle plate 4 barrel off various carbs.The carb itself works in the same way as a SU.

The Reducer is a IMPCO model "e" two stage.

And just for the record no! it does not and has not spat back ever even when race,ing.
This setup is good for about 350bhp so a 3.9 with that old blower on is well within that!.
Will try to post a link for more pictures of the setup in morning.
Forgot to mention this motor is gas only!..
No petrol on the car in anyway!.

Post by **Rossco** » Thu Oct 23, 2008 2:59 pm

Only sensible thing they say on that page is that LPG will tend to dry the bearings out. That's not to say it will but I did notice the grease degrading on mine.