Thread: Running higher grade fuel.

Well, TM shows up as KR it's a proven fact. Reducing it or removing it all together would not give any Kr but in fact just the oposite. If you were seeing 9* or any any KR for that matter then it sounds like the torque reduction downshift tables were modified,wich should not have been touched in the first place because it does nothing at a performance stand point. Or could have been caused by many other factors. Belive it or not I have never heard of kr at downshifts...well heard of it yes...but never knew anyone that had it happen to them.


And if these ''off the shelf tunes'' arent comming with increased timing tables to go along with the mods I'd be an unhappy camper.Or if the pcm that i got was giving me kr at an unuasual time like you were experiencing.

Any time the engine pulls timing for whatever reason is showed as KR. That being said, the PCM does pull timing at the shifts....and it's probably a combination of torque management AND knock. Like I've said before, you car will always perform better for the fuel it was tuned for. If you have a tune that runs excellent on 87, then running anything higher will hurt performance. Higher octane fuel needs to be compressed more to get any benefit, and raising compression on an engine makes it more efficient. 93 just helps you in the goal of running the maximum amount of cylinder pressure without damaging your engine.

Because 93 can withstand pre-ignition with a power adder better than low octane fuel. If you have a stock pcm and a supercharger, you should run premium....period.

Higher performance usually requires higher octane under normal circumstances.
If you have a tuner, and you modify the pcm to run with 87, the gains are there, but it's pretty difficult to make a GTP run on 87 without popping something once you start dropping pulley sizes.