Anyone tried a few gallons of racing fuel before in their engines or a fuel with a higher octane than 93?Does this give better performance?Is this bad for the car?

 

Only if you're getting predetonation (pinging)

 

Does nothing unless you can tune. Running too low of an octane will reduce hp though.

 

For example, E85 sits around 105 octane. I used that in my previous turbo car, but the performance will not increase unless you do something about the engine or add pressure to the intake. Generally spoken.

 

As far as E85 goes, the car can't use it at all. It would need to be set up for it.

 

Performance will suffer. The knock sensor will start fiddling to make the car driveable. Expect a lousy idle, rough running, and probably some CELs.

Not worth it.

 

Huh? The OP is asking about higher octane fuel. You're talking about lower octane fuel.

 

I also think lower octane gas won't have a noticeable impact if you normally cruise and short shift.

I've wondered about running lower octane gas on a road trip where you're just sitting on the cruise control. Probably not enough load to matter....

 

That is correct, thats why I used aem ems, bigger injectors + all the other stuff required. E85 by itself is no benefit whatsoever performance wise.

 

Lower octane fuel than recommended also = lower mpg - its not cost effective in the long run.