This is probably a simple question, but I don't know how the ECU works, so here goes:

With the SNAP Flash in place, how quickly can the ECU take advantage of the higher octane?

I typically drive to the track so that I get there on very close to an empty tank-may 1-2 gals. I put in about 6 gallons (60 miles, 2 sessions) and plan to refill after than for 2 more sessions. This would be with 100 octane.

Does the ECU adjust immediately as it percentage of 100 octane in the tank increases?

What specific improvement will there be? Higher horsepower at top end?

Thanks in advance of the educamation...

I can't really speak for Softronic and their specific software, but my experience with the stock software is that it is very quick to dial down and very slow to advance back up. This stands to reason since retarding timing too much too quickly will only hurt performance while advancing too much too soon can cause engine damage. So the stategy employed is very reluctant to advance timing except in very controlled circumstances. Your engine must be fully up to temp, and the subroutines to advance timing only begin their analysis under high load conditions...then they will slowly advance timing in incremental steps until maxing the values for the current table...you must then constantly max these values without any knock for a specific preset time which varies (extends) based on multiple feedback loop calculations...after the time lapse is confirmed permission is given to advance to a higher table. But again it is granted reluctantly and with other checks inplace to prevent hunting and unwanted shifts in power. there are many variables that come into play as to how long it actually takes that are very motor and driver specific..it could be half a lap, it could be more than a tankful of gas.

dw

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Atlas Gray Cayman S

As Davew said, it does advance up more slowly than down, although with the new 7.8.4 system you could have one cylinder going up while another is going down while the car tunes itself to the best possible match for the given circumstances. I usually put a mix (92 pump plus some 100) and then drive an hour to the track and run that down to say 1/4 tank then fill up with 100 and I figure by the time I get to 1/2 tank again it has probably maxed itself out. No idea how long it really takes, I just try to give it a little while to be sure.

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K-Man S

Hi

I logged the output of my DME during a drive yeserday and then flashed the 100 octane program and then logged again.

I compared this info with the stock timing maps and is convinced that the maps are adjusted realtime as the computer knows exactly how much each cylinder is knocking.

The maximum timing with the tuned map is 53.25 degrees and with the stock map I logged 42.75 degrees.

At WOT I logged high engine roughness numbers >25 and then at part throttle a few second later the timing would be back at 53.25 degrees with engine roughness numbers = 0. This on 95 octane fuel.

I can only conclude from my data that our DME's will adjust to its maximum timing when the engine does not knock and reduce timing when knock is detected in real time.

Well done Scott, I am really impressed with the application that you have developed!!!!!!!!!


Cheers

Herman

(My 3.8s now has 8000 trouble free kilometers on the clock and can out run any 997s on track.)

Thanks, Herman! Great info!

Greg