they use 91 and 110 fuel at the tracks because they are high compression motors or the car is FI. Is the 04 GT a high compression motor? i don't think so (??). most ricers are high compression motors i.e.: honda s2000, infiniti g35, integra gsr. they all get there horse power through high compression and we get out power from displacement. now, my question again which fuel is better for OUR moter? ask around. it's not that i'm cheap i just want to know what is best for the pony.

 

Octane, by definition, is the resistance to burn or detonation. The higher the rating, the slower the burn when ignited during the compression burn cycle of the piston. The higher octane allows for better control of burning for high compression engines. So we want to match the correct octane rating of the gasoline to the engine design to ensure complete burning of the gasoline by the engine for maximum fuel economy. Since the middle to late 80’s, engines are designed to use fuel injectors with computers to accurately control the air/fuel mix under all types of temperature and environment concerns. However the accuracy of the fuel injectors and computers is based on using the recommended gasoline for that engine.and clean emissions. Hope this is helpful.

 

I havent had a problem at all out of mine. Sounds great and it just rolled over 37000 miles.

 

Ahh... yes. One of the most debated topics.

As lbst8u stated, higher octane rating is needed to resist early detonation. Early detonation happens more in high compression engines. As the piston comes up to compress the air and fuel mixture, it has a tendency to ignite. If it ignites too early, you hear a ping (more like a knock) and you don't get the maximum power out of it. The higher octane gas is more resistant to ignition from compression.

Higher octane rating is needed when you put aftermarket chips in your car because the mod changes the timing and tries to increase compression ratios.

If you are not pinging, you are wasting money.

That's my side of this debate.

EDIT: PS. My 04 GT and the V6 run on 87. Ford requires 91 on the Mach 1 and Cobra (due to higher compression).

 

propellerhead. that was well put. only great minds my friend.

 

in my 96 cobra owners manual..it says to run 91 or better..but maybe its just cobras

 

im not trying to be mean man, but i actually got a real laugh out of that one...please explain how a chip increases compression ratios?? seriously man, all a generic chip does is give a little more fuel and add/pull some timing depending on the app...it cant peform miracles like increase comp ratio
that race gas they sell at the track is leaded...it will burn up your 02 sensors
4v's run on 9.85 compression, its needed

 

Yea, you're right. I was talking out of my axe on that one. I know the chips alter the timing so that might be why they require premium. I stand corrected.

 

i used the lower octane in my 5.0 and it runs like crap. It really runs like dirt when it gets low. It not good to run gas low all the time. I use the 93 octane and it cleans out and runs smooth.

 

with your mods, you should use the premium. I can't believe you have 93 octane where you are, all we have is 91 as premium down from 92 about 3 years ago.