I am particularly interested in your comments if you care to read this, but I also welcome comments from anyone with real data rather than speculation.

I am involved in the tuning of a drag race car.

It has a SBC motor with a Roots blower and mechanical fuel injection, as is very typical in drag racing.

We have 10.5:1 static compression, and we ran about 28 lbs boost with a 6:71 at 30% overdrive on a 355 CI Chev.

By my calculations this gives about 30:1 theoretical static CR.

This ran fine by staying a bit rich to avoid detonation

I think that at much over 20:1 you need extra fuel to avoid detonation, and we run about 15% over stoichiometric fuel.

We just put on a bigger blower and it might give over 40# boost, so we are going richer again.

I also have anecdotal evidence from the guys with the long arms and short legs that seem to be in abundance at drag racing meets, that they rum 11:1 and 45# boost, with comments like "don't worry mate, just make sure it's real fat".

I had anecdotal evidence on acetone as a detonation suppressor, and as a high octane high energy fuel. Acetone also tends to mix well with other fuels.

I have some experience and knowledge of water injection, and anecdotal evidence that water in the methanol improves power. This anecdotal evidence was from Neanderthal types who grunted a lot and back up statements with comments like "no sh*t mate, it just makes heaps of f***ing grunt".

This is not the type of comment that inspires my confidence, but I knew enough to know that it probably does actually work, at least in reducing knock, and thereby allowing a leaner mixture.

I also think water dissociates and plays a part as a catalyst in the combustion CO to CO2 at elevated temperatures and pressures, as well as extra expansion as the water turns to the gas state at any pressure at temps of over 800 deg C (I think it is 800 deg C).

The last few comments in the doubtful thread on small amounts of acetone vs fuel economy, inspired me to the extent that I might be able to get some "RELIABLE" data at last.

I used to run at 5.5:1 A:F ratio, but with the increased boost, I am aiming at 5:1.

I am wondering if I can run 5.5:1 methanol plus 0.5:1 water by mixing at 10% water in the methanol and jetting the mix at 5:1. Will this give more power and durability than 99.9% pure (as delivered) methanol. What would 10% acetone instead of the water do? What would 10% acetone as well as the water do?

I typically do theoretical calculations of air consumed vs fuel supplied to get a starting point based on A:F ratio, then I start a bit rich then reduce fuel until I get what I think is the optimum signs of heat in the spark plugs. I judge this by discolouration of the threads and the earth strap. At the slightest signs of beads forming on the earth strap, I take out timing or add fuel, depending also on how the threads look.

Remember this is drag racing, so the porcelain does not get time to colour, or by the time it does, it's all over.

First thing is, I don't have experience with blown motors. I judge a/f ratio by the discoloration of plug threads also. I have run methanol in 2 stroke high output engines  (single cylinder 500cc 128 hp) and like I said previously 10% acetone allowed leaning the engine further without damage and made more power. I also have experience with 4 cylinder 4 valve midget engines. Acetone is not allowed by the rules. The 4 valve(check valve) engines naturally aspirated are 24 to 1 compression. My experience shows that pure methanol makes more power and runs cooler than methanol that has been open to the atmosphere and has collected water. Maybe with 30 or 40 to 1 this isnt true. I do know that race fuel mfgs (such as VP, Sunoco, etc.) recommend and sell methanol that is between 99.6 and 99.95% pure with no water in sealed metal containers. I do know that methanol with excess water will not pass tech. Local track methanol in the US sometimes contains 10% or more water and makes less power in midgets, sprint cars etc. I know I haven't helped much, but I don't speculate or post anything I don't know is absolutely true.  

The first basic fuel check at the track is for specific gravity. Water adds to specific gravity just as nitromethane does. Without an extensive lab test it is hard to tell what is affecting specific gravity. NHRA has a certain range (SG) that the fuel has to be in. A call to your NHRA tech director should tell you what range they expect the SG of methanol to be in. When I raced in NHRA comp eliminator the car was weighed every run and the fuel (gasoline) was checked about every other run with a hydrometer. A high specific gravity reading automaticaly put you out, no matter what the reason for it was.

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