Taner Halicioglu

Altho there's generally no need for a full tank of it if you are bone stock...

-T

fairenough

Thanks for the replies. A few more questions/comments though...

I understand that in general crappy gas will make an engine underperform, but are you sure that 100 octane will make more power in a stock S4? For example, you can take your average car (e.g. Ford Taurus or something) which is perfectly fine with 87 octane and if you put 92/93/94 octane in it you're not going to get any extra power out. Now, I understand it's different with the 2.7T engine, but that's my question, whether the timing of the stock chip etc has the potential to take advantage of >94 octane. If it does, great, but has has it ever been tested (stock S4 on 94 octane vs stock S4 on 100 octane for example)?

Thanks again.

Taner Halicioglu

Especially on hot days, or after running hard for a while...

93 might be high enough, tho... but we don't get that out here in cali :-(

NASA racer

93 octane is right around where the stock setup is probably optimized...if you are running under particularly high temperatures and loads, 93 may not work.

Where we get into trouble is out in CA where the maximum we can get is "91" octane and even that now is pure crap because with the new blends (no more MTBE) it's highly doubtful that we are actually even getting the preignition resistance of 91 octane.

Taner Halicioglu

as far as heat of vaporization, etc...

NASA racer

how much difference? Went to the dragstrip once with my chipped tip S4 on a cool day with CA pump gas and ran 14.7. Took it back a few weeks later with 100 octane and ran 13.8.

krautburner_avant

Symptoms of carbon buildup?