Originally Posted by scippy (Post 4703994)

So my engines are 9 :1 comp. & if there tuned to 89 octane what damage would occur by continuing to use AV gas?.......burnt exhaust valve?......using it was a decision simply for it's shelf life.
I still have 50 gals left from it's initial fill up ...boat has only been used 5 hours since buying it........maybe a dumb reason to have used AV gas in the first place, but I'm sure auto gas would have
turned to varnish by now!........If it's too complicated to tune for AV gas with AS&M EFI's (not sure about ECM).....Thought the remedy would be pulse widths for injectors to compensate for AV
then auto gas would be less complicated!

Originally Posted by scippy (Post 4704067)

Trash I believe it's the opposite ...9:1 and tuned for 89 octane motors are running very lean with AV..........your suggestion is best advice fill w/91 and run. Can't answer about ECM I'm not sure.
articfriends yes shelf life concern & to do all this end around like zz28zz said, sad story in the end!

Originally Posted by articfriends (Post 4704263)

Another thought too, most tunes are NOT not very edge of burndown by any means, ie, if I tune a NA motor at 12.2 afr, guy changes fuel and it runs 12.5 its not going to just melt a piston. Theres always some margin in most tunes, I think your putting way too much thought into this, Smitty