Originally Posted by m3alabama
So here is an answer I cannot seem to get from anyone. I fail to see how any tune can tune for more peak power when using the same 91 octane gas. COnsidering there is ample threads and evidence that even with the STOCK tune, the engine can't make its peak horsepower and is limited by knock sensors and not being able to fully advance timing.
So how does one expect a tune to increase power output at peak with using 91 octane? I can see it maybe improving some power lower in the curve and in the middle but it should be essentially impossible to improve peak power on 91 given with a stock tune it is unable to hit its targets.
Mike can you chime in
Sure, thanks for your question.
There is undoubtedly a gain on 91 octane gas, although it's certainly not as significant as the gain on 93 octane and above. On 93 octane you ran run slightly more ignition timing than on 91, due to the propensity for higher octane gas to resist pinging.
There are many stock cars that actually hit their targets, although some of them may not. This is due to a number of different reasons, mainly fuel quality, and environmental conditions. However, there are some tricks that can be made to the calibration that 'help' the car achieve it's targets faster. You should expect a properly tuned car to achieve higher targets than a stock car, even on the same fuel.
There are also a few other things that can be done, such as slightly modifying the knock strategy which can also help the car achieve it's targeted timing.
I hope this helps.