What octane to run on 4.6 GT Anyway?

[jas142]

I always use middle grade (89 octane) but is there any real performance benifit to using 91? Automatic 2004 GT

 

[TorchRedGT02]

I don't believe there's any performance advantage using a higher octane than recommended on a stock vehicle (87 octane)...just piece of mind.

 

[el_kid_1]

For a stock engine, it won't improve performance running higher octane gas than what is recommended in the manual. Once you get started modifying your engine, you will see the benefits of higher octane gas.

 

[Bulldog6Z6]

if you move up ur timing it will help stock you wont notice a difference.

 

[mnm99]

89 stock , 94+ blown

 

[derek02gt]

i have gears and exhaust..(slp loudmouth)..can i continue using 87?

 

[SVTStang03]

Yeah you're fine with 87.

 

[Islander03GT]

87 is fine if you're stock... especially with gas prices how they are

 

[JonJon]

87 man
and i don't plan on a TA anytime soon

 

[sickstickGT03]

I run 87 on the street, but would it benefit going to a higher octane when I go to the track?

 

[98stallion]

I run 87 on the street, but would it benefit going to a higher octane when I go to the track?

you'll get less power more than likely. the most power you'll get is by running the lowest octane possible without detonation

 

[Dr. Black]

A while back motor trend did a study on octane, used several cars, honda, saab, MUSTANG GT... with each car used the recomended fuel (mustang 87). Did dyno test for hp and tq, and a gas milage test. The mustang made less power and got less miles per gallon with 89 and 92 than with 87 (not by much but stll worse). I would not use higher octane gas unless SC or Turbo or other major type of performance mod.
Hope this helps. (remember your cars computer was designed to run with 87)

 

[DrK MrK iV]

I use 91 on my stock 04 engine. Dunno why though... Just out of habit I suppose.

 

[u_s_marine]

I use 91

 

[White Stang]

I always use 91

 

[FallenPhoenix]

There's less actual fuel to burn the higher the octane rating, so the lowest you can go without pinging is best. If you do get a little knock you'll pick up some power with higher octane just by preventing detonation.

 

[01'TRUE BLUE GT]

Using anything higher than 87 with stock timing is a waste of money ... you don't need it. Higher octanes burn slower so you may actually hurt performance using it in a car that doesn't require it. My car ran great on 87 before I got my timing adjuster, but now I have to run super.

 

[ScottJ]

I need to add to this. Even stock if you live somewhere that gets hot in the Summer and the EPA forces reformulated gas (RFG) on you then you need 91 or you'll knock and ping.

My GT will ping on 87 any time of year unless I drive like a little old lady not from Pasadena.

I can get away with 89 in the cool weather.

 

[fpb96GT]

I have stock timing, but after I installed my KN FIPK, I noticed a knock, so for now I use the high octane and it takes the knock away. I do plan on getting the timing adjusted once I get it out of storage though.

 

[blk2003GT]

I always use 91

With stock timing your are throwing your money away. Go with the factory recomended 87.