Compression

[CB7lx91]

OK I'm gunna convert my car to run on propane. yeah I know, loss of power, more expensive, yadda yadda yadda. It's for a senior project. The ideal compression for a normally aspirated engine running on propane fuel is 12:1. That's pretttyyyy high.

My question is how do I get that high or damn near close to it?

I heard the h23 swap will bump to maybe 10:1

And that flat headed pistons will bump it up bit

[NAiL05]

H23 stock is 9:1 comp...

[preludeman92]

So, how are you going to go about converting to propane? Are you going to end up going with a carb setup of sorts?
What makes you think you need 12:1 compression to run with propane?
I have a problem thinking that forklifts run 12:1 compression, and I know a stock chevy small block is under 9:1 (xtreme4x4 runs propane on a couple projects).

[wed3k]

i dont think he knows what he is about to get into to...

[CB7lx91]

I read an article this guy created about how he converted to propane, and in it he rattled off all these facts, one of which was that propane combusts most efficiantly at 12:1. His car was carburated, don't know if that makes a difference.

[preludeman92]

You do realize you're going to have to run a carb, right? If you spray liquid propane into the combustion chamber, even at 8.8:1, your motor will go BOOM in a hurry!
You have to run the car off of gaseous propane.

You're best bet would probably be to contact Bisimoto and see if one of one of the f18a's he's imported has a carb manifold on it he could sell you. Then it'd be a matter of finding a propane carb and a regulator for it. I'd also run a heater on the propane line so that you make sure the liquid propane is vaporized like Bully Dog does on their propane injection kits for diesel trucks.

And for the record, you don't need 12:1 compression for propane to work. Propane just has much higher octane than gasonline, so you can run more compression. If you're really interested in doing this, you can buy complete conversion kits for small block chevy engines. The kits are catered towards the offroad crew.

[d112crzy]

H23 stock is 9:1 comp...

nail, stop spreading false info damnit. You've been doing a lot of that lately. I'm gona karate chop your ass.

An h23 head swap will not raise your compression, unless you mill the head.

An h23 has a 9.8:1 compression ratio.

your exhaust will smell freaking nasty. I hate the way forklift exhaust smell.

[NAiL05]

nail, stop spreading false info damnit. You've been doing a lot of that lately. I'm gona karate chop your ass.

An h23 head swap will not raise your compression, unless you mill the head.

An h23 has a 9.8:1 compression ratio.

your exhaust will smell freaking nasty. I hate the way forklift exhaust smell.

I have bad memory i just know its in that range.

[CB7lx91]

Haha thanks guys, I'm most likely not converting my car to propane, my mentor has a chevy truck and the conversion kit, so I might as well just convert his.

[Jarrett]

The reason for higher compression on a propane engine is its thermal properties. It produces less energy when burned compared to gasoline(actually just about everything does which is ONE of the reasons alternative fuels are so slow to get popular) so it makes less power. Less energy=less power. So the compression ratio is increased to created more energy in the combustion cycle. Anything higher than what is necessary to make it run efficiently is done so because its higher octane rating allows it to do so. I've seen 4 cylinder Ford engines running 16:1 on propane, and it was fuel injected. So if high compression is your goal then you should be able to do it. Fuel injection is possible with soft lines,a fuel pressure regulator,(maybe bigger injectors.....maybe) and a tune sent down from God himself. It's obtainable.

[spray_bombed]

flat top pistons wont raise your compression unless you currently running concave ones

[TheNextEpisode]

I read an article this guy created about how he converted to propane, and in it he rattled off all these facts, one of which was that propane combusts most efficiantly at 12:1. His car was carburated, don't know if that makes a difference.

Might you be mistaking an CR of 12:1 for an AFR of 12:1?