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Message: [QUOTE="Rich Rohrich, post: 1063368, member: 16241"] I guess you didn't have ENOUGH chemistry afterall. ;) Octane numbers in excess of the engine's requirement will not hurt performance. BUTTTTTT, using a fuel with a distillation curve that isn't designed for the application whether it is a high or low octane fuel can have a negative impact on performance. The octane rating of the fuel is probably the LEAST important specification for the average rider to look at. In the case of the Koch Power 110, the performance drop you'll see running it straight (and you will likely see a drop) is due to the 90% and End Point temperature of the fuel's distillation curve being set to high. The end point is 320f which is way too high unless you are running in the desert or at really high outside air temps along with extended WOT runs. Mixing in pump gas won't fix this distillation curve problem. You need a fuel that has a lower percentage of heavy aromatic hydrocarbons so the end point will come down and that part of the fuel will be usable. Fuels like Koch 110 & VP Red are designed for engines with more time and available heat in the intake to vaporize the fuel across the whole distillation range. These fuels would work well in a Big Block Dodge with a dual plane manifold peaking at 5200 rpm, but it's not the best choice for a small bore two-stroke. This is closer to what you are looking for in terms of a distillation curve for a two-stroke. Distillation (deg F) 0.01............108.2 0.05............141.2 0.10............154.2 0.20............174.5 0.30............192.7 0.40............204.8 0.50............210.4 0.90............223.0 0.95............230.5  0.99............266.8 Dr. David Redszus the blender of FirePower race fuels gave me these numbers as typical values [b]at the refinery[/b] for Northern Illinois in the summer. 10% - 158.0 50% - 250.0 90% - 374.0 End point - 437.0 The EPA can provide the seasonal temp ranges for your area, but there are a couple of key points to remember. The EPA seasonal values only have to be met at the refinery not the pump. The 50% distillation temperature in Illinois (summer) has an acceptable range of [b]170-250F[/b] . Think about that. A single point on the curve can vary by a larger range than most race fuels change from 10-90%, and that is at the refinery point. By the time it gets to your engine the range is even greater. I have a fuel quality study done by American Automobile Manufacturers Association from a few years back. They did tests at the pump at a wide range of locations. I'll try to dig it up , but the basic point was what comes out of the pump is vastly different from the "numbers" the EPA quotes. The relative quality of pump fuel is really bad. What I'm getting at is the idea that pump fuel won't undo a bad race fuel choice by combining the two. [/QUOTE]

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