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I have been experimenting with a number of different octane fuel ratings and types of late. One thing that caught my attention is that the car performance varied with fuel type. This variation has been covered on SSc to a large degree, so I won't rake over that again.
What I am interested in is to find out if anyone else has also noticed that on changing fuel type an adaptation run is not a bad idea at all. Without an adaptation run I got the feeling that the optimum ignition point was severely in imbalance across the rev range. Doing an a few brisk runs soon sorted that out. I put that initially down to the remains of the old fuel and new fuel mixing and causing an imbalance. After a refill of the new fuel, things got better.
But then I started wondering whether those brisk runs were in fact having the effect of an adaptation run.
Consider this: the ECU alligns itself to the optimum performance of your engine setup. This optimum performance is without question highly influenced by the type of fuel used during the adaptation run. When you change fuel, the ECU is still using the data from the previous fuel, until time has passed and the ECU has re-alligned itself to the new fuel.By doing a couple of quick runs, you are forcing the ECU to recallibrate itself in line with the new fuel at a faster rate.

Am I just imagining this, or are there sound technical reasons for this? Perhaps this is already known about, or did I stumble on a major new discovery?

Stanley
 

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No marble count needed Stanley...

Trionic is actually continually adaptive. Changing fuel does have an effect on the overall combustion process and the ECU needs time to react and adjust. The time constant for doing this is purposely set the way it is in order to avoid incorrect adaptation to a spurious cycle of very short duration, be it good or bad.

Similarly, we've all noticed that our cars are faster in the winter. This isn't just simply down to the denser air/fuel mixture, but also the fact that the system adapts and learns there is less chance of knock in colder conditions.
 

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Indeed you must have missed the other videos that were linked to at wrxfanatics.com where I did a reasonably scientific test of Torco Accellerator, a fuel additive.

By raising the octane level several octane numbers (not several "points" like most octane boosters do) I was able to make a markedly noticable difference in boost pressure.

I can't even begin to guess at the amount the timing has since been advanced as now I regularly run the additive.

I found as much as 2-3 extra psi of boost on very warm days by going from 91 AON to 95 AON on a completely stock car. On a modified car it's safe to say this might be even greater. (If the tuner leaves as much room for adaptation as Saab did.)

Dubbya~
 
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