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What to do to get more power out of a Propane motor

4K views 10 replies 9 participants last post by  chvyhs 
#1 ·
So I'm building my buggy right now I was trying to figure out how I could get more power out of it. It's pretty much a stock 22R with a header and propane injection. What are the easiest ways to get more power cheap? Port matching the head and intake manifold? Plug the coolant lines to the intake so the intake stays cooler? Thinner head gasket? Mill the head down a couple .00010"? Better cam shaft selection? Head and valve work?

List my options from cheapest/easiest to expensive/difficult.

Thanks
 
#2 ·
To start with...I doubt that your head is even .001" flat not to mention .0001"! I'll give you a few ideas, first, you can probably advance your timing some. Do you have an aftermarket cam? You can also fly cut the head....just milling it flat is going to take a couple thousands off and will increase your compression ratio very slightly to a lot depending on how much material is removed. Other than that....get a v8 or don't stress about pulling every last pony out of your 4 banger.
 
#3 ·
You can only, generally, move up about 0.5 CR points by milling. Fly cutting? It ain't a V-dub air cooled motor...

If you are trying to actually gain power with it, you can increase your comp ratio by pistons, advance your timing, and/or add a turbo.
 
#6 ·
The same tricks that help make power on a gas motor will work to make power on propane. It sounds like you already have some good ides and know what to do. Contact the guys at got propane, they are awsome about answering ?'s and stuff and if you need parts you should buy from them!
 
#8 ·
Basically anything that will bump a gas motor will do the same in an LPG motor. With LPG you can safely bump the compression up without detonation as well as the timing. You can run 11:1 easily and I've seen guys running up to 12.5:1 with propane.

BTW I agree, any good rebuild should have the deck flycut. Good measure to take to assure a flat, true surface.
 
#10 · (Edited)
If you're running the carb manifold I think there is more power to be had from the EFI intake. I haven't run any of our engines on the dyno however the buttdyno tells me that our propane engines that use the EFI manifold are stronger. If you compare the area of the throttle housing on the EFI to that of the carb base adapter it's fairly easy to see the EFI is larger. So far all our engines have ended up at .040 over, a Comp cam, and header. Turn the 40s with no probelm. Also as mentioned above you can run the timing way advanced with the high octane equivelent of the propane. We are currently running the 225 mixer as apposed to the 200 that some folks are using. Not sure how much if any differnece that makes.
 
#11 ·
I should have meantioned that I"m building a Formula Four and I'm trying to stay within the class rules. I also have the Got Propane kit.

Thanks for the advice. I'm going to see what kind of head work is offered at my local machine shop and get a better ignition system for now. I'll have to keep my eye out for a EFI intake. It sounds like it's worth a try. If I can't get enough out of the 4 cylinder, I'll probably end up with a 4.3 V6.
 
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