alcohol AND propane

[onefastjackass]

Originally posted by JayC
Because there are people doing it already.

Good finally we are finding out that some people are doing it successfully.Any other insight like how much of each is being injected.Any problems with the spark going out etc. etc. Give us some details so we can all learn from it.

 

[DMan]

I don't think the spark will go out. If anything is certain, its likely that you risk overfueling, but thats not a catastrophic situation.

The only downside I see is trying to tune 3 fuels now instead of just two (I have trouble enough with just one!) I think mycarsucks summarized the benefits of each fuel quite well their earlier post - with one exception.

I think that adding more alcohol at this point will *lower* the weighted average octane rating (if there is such a thing) since propane has a much higher octane rating on its own.

Alcohol will cool the air/fuel mixture down, allowing you increase the charge density and hence power. The intercooler does that to a certain extent - alcohol makes it better I believe.

Overall, I'd be curious to see the results of such a test.

My personal opinion however, is that if you have to use gasoline, water-alcohol, and propane to get the same results as race gas, isn't race gas now less hassle than 3 fuels and 3 fuel systems?

 

[tracer]

My personal opinion however, is that if you have to use gasoline, water-alcohol, and propane to get the same results as race gas, isn't race gas now less hassle than 3 fuels and 3 fuel systems?

Don't want to shoot my face off until things are hooked up, but to my thinking alcohol is the only fuel that's a hassle. That's my opinion after running it for about 3 seasons. The tank is small and you go through quite a bit of it. Gas.......well ya gotta have gas. Propane, people are talking about 3-4 months on a bottle, so really refilling the alky is the ongoing downside. In fact that was one of the reasons I wanted to switch to propane. Tuning and level of complexity may be an entirely different story . My question was probably inspired more by laziness than anything else (not wanting to remove the alky kit). I appreciate all the feedback and may work up the courage to leave the alky kit with a small jet in place and just see what happens.

 

[Turbo__Tim]

Tracer, you are on the right track there. I began using propane late last year and in brief testing was able to run both systems at the same time. Unfortunately I am experiencing a weird electrical problem with the car, and until I get that resolved testing is out.

All I can add to this discussion at this point is that I found the alchy pump speed needed to be turned on very low in order to work. I suspect this is related to the fact that the propane cools the cylinder temps to a point that alchy isn't needed. I managed to get 1 psi more

Alchy 'likes' it hot. It also 'likes' high timing. If I had to guess I would say that in order to drive the boost and timing to higher levels, one would need to move the alchy turn-on point to about 20psi then slowly raise the timing and boost from there.

Dman makes a good point when he says why not go to race fuel. He is right unless you are one of those people that have stepped up to the convenience of propane, still have an alchy kit and you are one of those people that like to tinker, and see how far 'pump gas' can be driven.

We may find that alchy can be injected at one-quarter of previous levels at the point where the propane begins to loose it's effectiveness as a kind of insurance to moderate cylinder temps, and guard against a batch of bad gas, or changing weather conditions.

However it turns out, it should be interesting.

 

[DMan]

Good stuff..Propane definitely has high octane but I don't understand how propane 'cools' things down, or that it can cool things down better than alcohol or water.

My ignorance here but is the propane being injected as a liquid or a gas? Does propane have a higher specific heat and higher heat of vaporization than water-alcohol? If the propane is being injected as a gas, I don't expect the same heat-transfer effects with propane that you get with liquid alcohol-water injection.

Comments

 

[Turbo__Tim]

This has been addressed before, but OK just for you,,

There is no cooling affect on the intake charge with vapor propane injection. When the vapor mixes with the intake charge the flame front is slowed down. Allowing the piston to reach higher compression before the entire mixture burns off. A clean burn that leaves little residual un-burnt fuel to pollute the next intake charge.

In short it raises octane.

If you followed the 'Alchy and Propane' thread you would see where mixing the 2 mediums (alchy-propane) is a possibility becaust they control detonation differently.

Sorta like adding alchy to 98 octane to get additional benefit of cylinder and intake charge cooling.

Ok?

I believe that Jay Carter, or Bruce could explain it better detail.

 

[Jon E]

With a propane kit how much propane is injected during a run? What size jets are you using and what are the regulators set at?

 

[Turbo__Tim]

Difficult to say. Bottle pressure at 80-100 lbs? Pressures vary...

There is a second valve that I open about a turn and a half.

Guess I'd have to get a ballon and put 12 seconds of propane in it to to get you an answer to that one.

I believe that I heard that the propane comprises 5 percent of the intake. I could be mistaken.

Another question for Jay Carter..