1fast50

Why do the cobras require Premium fuel? whats so special about the engines?

Triisomy21

lower octane fuel detonates (explodes) at a lower compression. You dont want the fuel to explode before the spark is fired. You'll f up your engine.

SXGT

BUT if you have an old GT and its take 89 , buying the premium is a WASTE of money, your car has to have a tune for 93 before you can make full use of it. Cobra obvioulsy have this tune

SVTBill

so 99-04 are tuned for 89 or 93?

SXGT

yes, but let someone conform me , cause i have a 97

akelemecz

I don't care if I had a tune or not .. I buy 93 because its just a better grade gasoline .. I have a dyno tune on 93 for my car .. but In my opinion .. if you value the longevity of your car .. always give it the best...

Lord Ryan

Higher octane isn't necessarily better. But higher octane gas typically contains better detergent mixes (here at least). It's a trade off. Because if you have a higher level of burn inhibition, you will have a dirtier product leaving on the exhaust stroke. A truck with 8:1 compression ratio, for instance, won't have had a very thorough burn on premium gas; while a Cobra with higher compression and an advanced timing curve may suffer detonation with regular. Most gas doesn't even have varying levels of octane or heptane. Just more chemicals mixed in to simulate the same effects.

oxfordgt

I hope you like wasting money cause thats what you are doing. 93 is no better then 89. 93 has a higher temp at which it ignites. When you advance your timing you allow more air in the combustion chamber which makes it hotter when you compress it. The cobra's have higher compression ratios (NA) then GT's which causes more heat and that is why you need to run 93 octane. Running 93 in a stock GT is just a waste of money and does ablosutly noting for your car.

SXGT

+10000 everyone should read this!

akelemecz

I'm tired of you cut and paste guys .. if thats the case.. 105 octane fuel is just there to be a huge gimmick! ... 93 is a cleaner fuel with more additives etc... allowing your fuel system to run cleaner... and for $.10 more a gallon .. 1.50 a week .. and 78 dollars a year its worth it ....