Mike:

My guess of 4hp is just that; a guess. Your noticing more difficulty coming off the line, and the sudden power surge as the rpm comes up indicates my guess was probably too low. The point I was trying to make is that with a really high specific output a two stroke becomes a royal pain to keep in the increasingly narrow power band. Again, my 14.5K to 15K is a guess. But you will have to crank some nasty engine speeds to get the power up, and the rpm will be your con rod limit rather than the hp developed.

On the fuel. Assuming it has a needle roller bearing on the big end of the con rod your 5% oil should be enough. The problem with decreasing oil to minimum is that you have to test to destruction. Then buy another engine and try again. Stay at 5% oil. A lot cheaper.

The methanol is what gives you the power, nitro methane allows more methanol to burn by sourcing more oxygen that the engine can get from the atmosphere. For a given power output you have to burn a given amount of methanol, by adding nitro you can burn more methanol and therefore increase the power of the engine. Nitro content up to 65% is available commercially, but remember you are going to burn 6 or 7 times as much as you will of a straight methanol/oil mix in the same run time. Gaining power through a fuel mix has a rather high price.

Propylene oxide is used with high nitro percentages, with high nitro the ignition can become erratic, the propylene oxide makes ignition more consistent. As I said in the earlier post, more than 2% generally isn't needed, it just raises the cost of the fuel.

Again, with high nitro percentages the fuel tends not to stay mixed. Amyl acetate, 2%, keeps the various components mixed nicely. Acetone or methyl ethyl ketone also work, but not quite as well.

I've been out of "Fuel" racing for quite a while, there might be better/later information available from a kart racing site, or someone racing two-stroke motorcycles. Think about a 500cc motorbike pumping close to 200hp.

Bill.