[Charles Rainey]

As I get to play on my dyno quite often, I have learned a lot. In the early day, EGT's was all we had and we learned to tune with them and read spark plugs. But most know that EGT reading are on a bell curve. You can be reading on the up side or reading on the down side. You must determine which side of the bell curve you are on. With the advent of the O2 sensor, we got yet another tool to work with along with the EGT. Then we got to learn about BSFC. All 3 of these together will let u tune the engine pretty doggone close right off the dyno and just like was stated, every engine will be different. The swirl effect in every engine has its on characteristics and the amount of Octane you run will affect the curves. You most certainly indeed can add too much octane and slow the burn cycle down too much. Most (not always) of the time you want the octane to be matched as closely as you can to your optimum burn time. I have actually had the octane so high, that I continued the burn thru the header and the EGT temp was extremely high. We try to match the engine as closely as I can get it to O2 sensor readings AND BSFC. I then look at EGT numbers and try to get close to that on the track, but I also try to have at least one O2 on each side to keep me on the honest side. O2's are funny, as they get warn and used up with lead fuel, their cycle time goes down, so dont keep yourself feeling too happy about not spending $40. Keep new ones too make sure of your numbers.
Oops did I just open myself up for scrutiny> Yep sorry my $.000002.
charles