dan_uk

I have a stock F20c with intake/exhaust/ AEM ECU.
I was gonna get tuned for 100octane since I figured a stock engine wouldn't realy help with a super high octane

Now I can't find 100octane locally so I have a drum of 110 Octane leaded!

I was going to mix it down 50/50 with 93 pump to get around 100octane or is it worth going higher?

dynos:


So the original tune for 93: (stock ecu vs aem):
[attachment=7562:dyno-small.jpg]

The baseline with 93/107 mix:
[attachment=7560:carter-dyno1 (Large).jpg]

final tuned with 93/107 mix:
[attachment=7561:carter-dyno2 (Large).jpg]

Gernby

I don't see any reason to go higher on a stock engine. AFAIK, the higher octane would only be beneficial if you raised your compression, went forced induction, nitrous, etc.

Duke Togo

yes high octane race fuel like 110 (unleaded) will make the car noticeably faster even without tuning but the cost of it is prohibitive and it would be cheaper to do other things.

you not supposed to use leaded gas as it kills emission systems FYI

barrett4bama

How will it make the car "noticeably" faster? Especially if not tuned for it?

dan_uk

my tuner said the same I'm not looking for more than 3-4HP but if its less than that I'll stick with the 93 map will post the dynos later

if octane doesn't help though how do people seem to be able to make good power from E85 on a stock engine?

Duke Togo

Every race gas brand is different but most of them arent using the detergents found in typical 91 octane that reduce the energy output of the gasoline. Since the air flow isnt changing and the spark doesn't change. The power output of the fuel usually resulting from a more efficient burn or from other chemical additives increases. Running a tank full of 110 unleaded octane in a car used to 91 octane feels like rocket fuel. I've even used avgas which is up to 134 octane with good results.

Angerman

If N/A I would personally just get tuned on 91/93...

b.r.i.a.n.

the higher octane may or may not help. with very good supporting mods, chances are you're able to reach mbt with pump gas. if you're not able to reach mbt because the fuel burns too quickly and you're forced to back off ignition timing, then this is where e85 or any other higher octane fuel will help.

AutoUnionAG

I don't know where you get your information from.... Unless you have knocking issues with the car already then the higher octane may help clear those up and give the illusion of a faaster car; but really youre just band aiding an issue.

Cars make more power from increased airflow, lack of fuel and additional timing. Better fuel allows a more aggressive setup... Unless you're doing one of the those three there no need to waste money...

Mike21

higher octane = higher resistance to pinging.

It'll allow you to run more advanced timing.
For a street car it gets expensive and it's not really worth it, IMO.