Greetings! Is it possible to tune ECU settings to increase compression ratio and adjust sparks timing for higher octane fuel for octane 98 gasoline or ethanol E85 octane 106?
I see no reason it is not possible, no one has done so simply because it would not be economical to decompile and reverse engineer the software to set the valve timing and spark advance to get more horsepower. Simply swapping to the Otto cycle version of the engine would be much cheaper, if you want more HP.
No so much about getting more horsepower, but I'm hoping to tune the ecu for effective use of high octane fuel for better fuel economy on E85 See: Converting to E85 (ethanol fuel) - Turbobricks Forums
Compression ratio is air volume with piston at top-dead-center divided by air volume with piston at bottom-dead-center. How the heck do you change that with software?
Variable intake valve timing makes that definition obsolete. When computing actual compression ratio, one needs to figure the cylinder volume when the intake valves close, which is much later than bottom-dead-center. This is variable and controllable.
This picture is accurate for the Gen 2 Prius but is in principal how all Prius work, details will vary. Exhaust timing seems fixed, but intake timing varies under differing conditions. I do not think 'software' could alter the range of intake timing, just where in the range a Prius chose to be. At cold temps, idle, and when starting, this is a low compression, very Atkinson style engine, at medium speeds and loads, it becomes a more Otto cycle, high compression engine. At high speeds it becomes more Atkinson like again. Could the OP do a better job than Toyota knowing he had high octane gas? It is possible, but I do not think anyone has succeeded so far.
