The Mustang Forum for Track & Racing Enthusiasts

Taking your Mustang to an open track/HPDE event for the first time? Do you race competitively? This forum is for you! Log in to remove most ads.

  • Welcome to the Ford Mustang forum built for owners of the Mustang GT350, BOSS 302, GT500, and all other S550, S197, SN95, Fox Body and older Mustangs set up for open track days, road racing, and/or autocross. Join our forum, interact with others, share your build, and help us strengthen this community!

What's the recommended Fuel octane for Boss 302?

Hi guys, I'd like to get your opinion on what's the best fuel to use in the BOSS. Regular Unleaded @87 octane or Premium Unleaded @ 91 octane? Unfortuantely 91 octane is the highest available in Utah. Thank you all.
 
My understanding is you can run any octane fuel and the PCM will adjust spark timing to take advantage of octane up to 91. You're safe running 87, but will have experience decreased power. Therefore I always run 91 or higher, especially on track. TracKey is supposedly a different game altogether, but we won't know for sure until it's released.
 
1,255
2
GA
My '08 Bullitt was the first Mustang to use the variable octane feature. It ran on 87 OK but you noticed the power difference and the gas mileage was worse, bad enough that I found that I spent less money on gas in the long run by using 93 instead of 87. My new 5.0 appears to be the same way, so it is 93 all the way for me now. Once I get my FRPP tune I won't have a choice. 91 should be about as good. Like any other performance tune Track Key should require 91 minimum, so it is best to run that all the time so you don't have to worry about it.
 
What Gary and Ken said.

The owners manual for the 5.0 engine says it will run on 87, but for best performance 91 and above. Also up to 10% ethanol and no E85. The Boss supplement does not say anything about octane, but the 2012 Mustang Boss Specifications sheet (available from the Ford website) states 92 octane. I ran out the 87 put in by the dealer and have been using 91 since (I think I found 93 once). I live at 5000 feet so already sucking about 10% less air pressure as it is, so for me 91 will do - octane is not going to make up for a 2 psi drop in air pressure. I suspect depending on where you are in UT about the same for you. Wonder what the MMP guys are running in their Boss's (I will be there next month)?
 
MNG_BOSS302 said:
I live at 5000 feet so already sucking about 10% less air pressure as it is, so for me 91 will do - octane is not going to make up for a 2 psi drop in air pressure. I suspect depending on where you are in UT about the same for you. Wonder what the MMP guys are running in their Boss's (I will be there next month)?
I don't know but I live at sea level and noticed immediately my car felt stronger than the MMP Boss car I drove. Knowing we were at approximately 4,500 ft I asked about the difference and Gunnar stated they were down on power 5-8% compared to a car at sea level.
 
5 DOT 0 said:
I don't know but I live at sea level and noticed immediately my car felt stronger than the MMP Boss car I drove. Knowing we were at approximately 4,500 ft I asked about the difference and Gunnar stated they were down on power 5-8% compared to a car at sea level.

Yeah, you sea level guys get all the fun, rub it in Rick - if I ever drive my Boss down I get to look forward to all the NA power. It's still an awesome car!!!
 

TMO Supporting Vendors

Top