tubi

For track day use. Any idea?

joec500

unless you have the software to fully exploit high (100 + octane) it's a waste of $$

edkwok

No need. 91 is good enough. Coilover is better than 100 octane fuel. Or learn the lines, apex point at the track is more important than power on track. Eventually someone is gonna pass you.

I was at California speedway last Sat. I can't do nothing but letting the S2000, GT3 and 335i passed me.

I have 91 APR, testpipe, PSS9, Milltek exhaust.

SilverB7FL

its pretty fun just makes the exhaust a bit more smelly esp. w/o a cat

TwentyValveB5+S4

If you're on stock programming... the most the ECU will likely take advantage of is 93. If you can only get 91 in your area, you can throw a couple gallons of 100 in there to mix and bump your octane up a bit. As your ICs heatsoak and your IATs rise, you'll need the extra octane to compensate.

You don't want to run straight 100 on a stock program.

Now, to take *full* advantage of higher octane fuel, you'll need a program that's designed for it (all the chip tuners have race programs available). Usually race profiles run a little more boost and a lot more timing.

Do not run leaded race gas if you care about your O2 sensors and catalytic converters. MS109 is about the best you can do for unleaded race gas, and will be plenty for any race file.

Youreviltwin

Unleaded fuel

tubi

Do you notice any difference in power and performance of the engine with racing fuel?

TwentyValveB5+S4

meaning he has an ECU program that was designed for the higher octane

Youreviltwin

100 octane file = chipped.

John Stahmann

Having the correct programming is the key if you want to run unleaded high octane gas. To run leaded race fuel you will need to remove your cat or you will ruin it.

Leaded race fuel makes your exhaust tips nice and white and smells so good!