Originally Posted by rsilvers
How does running it in my own car prove a difference without a dyno test? How would I measure the difference? iPhone app G-meter maybe?
Is adding octane boost the same as buying 93 octane? Then at least you could test on the same day with the same weight fuel.
I'm not talking about hp, that you will only notice in SOP. You will notice the difference in fuel economy and acceleration. Yes, there are apps that you can use for a ballpark. No, octane booster is not the same thing. That, and it takes a bit for the LTFT to recalibrate with the new fuel. The only way you would get relatively accurate numbers would be to be near empty on 93 when you pulled onto the dyno and have 10 gallons of 87 ready to go in it. The timing will retard to avoid knock faster than it will advance. I would venture a guess that it over-compensates and then adds slightly.
I get really cheap dyno work, but that doesn't change the fact that it's inconvenient, takes up a few hours of my time, and I would have to deal with a crappy running car for the next few weeks. If you aren't accepting the tests that Top Gear did on a dyno (not a Focus, I understand), then I would recommend calling a nearby shop and getting an opinion/cost for having it done. Then you could be the one to settle it.
Everybody always wants somebody else to do the dyno testing. Try being the somebody else