dragstart

I have easy access to Sunoco 100.

Going from 87 W/ 10% methanol that the dealer put in to 93 made a big difference, at least it seemed so.

What would the 100 do?

Would the 100 be better for one of the advanced tunes?

Glenn

Has to help some you would thing....... but then on the other hand, I would think the 100 would werk better with a little higher compression ratio

2010MustangGT

Probably nothing but burn a hole in your pocket.

The octane number is a measure of its ability to burn evenly and resist spontaneous combustion. Hence you're getting a more efficient burn. The octane rating tells you how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine.

Higher compression ratios require higher-octane fuel. So being that the compression ratio wont change... and there's no knocking at 91-93, chances are you're just over killing it at 100.

PTRocks

Well, it will really depend upon how the engine responds to the ECU's advancing the ignition timing with the fuel. The ECU is programmed to run the engine at its knock limit. This is why there are useful gains from 87-93 with this engine.

Ltngdrvr

The higher the octane of the fuel the slower it will burn at a given compression ratio and timing advance.

So, unless the engine needs the higher octane the higher octane can actually lower the horsepower and reduce the fuel economy due to the slower burn.

Now, the engine is actually designed to make more power with 91/93 octane over 87 based on the ignition advance built into the tune and based off of the spark knock sensed by the knock sensors. But the timing will only advance so far so just throwing higher octane gas, beyond 93 octane, won't make more power.

hawkeye18

I bet if you get a tune for 100 octane, it'll make quite a bit of power. Without a tune, though, you're pretty much just pissing money into your gas tank.

assasinator

dont oversimplify the ECU. ignition timing is only part of the changes better fuel makes. cam timing changes happen also. my bet is 100 octane WILL improve power in a few tankfuls. its not like 11:1 cant use race gas.

tstrick9

I can get 100 octane right at the pump at a local Texaco station. My only concern is how much do they actually sell, so how long has that gas been in the underground tank?