drzeeba Posted March 25, 2014 Report Share Posted March 25, 2014 What octane do you use? It's almost impossible to find anything above 91 around here. It's either that or 109 that I found at one spot. Everything I see recommends 92 or better. What additive do you recommend? Can you have too much octane? Link to comment Share on other sites More sharing options...
CSX4833 Posted March 26, 2014 Report Share Posted March 26, 2014 There are several discussions on this forum about octane and whether or not 92 is better than non-oxygenated 91. The cenus seems to be non-oxy 91 is better for performance and mileage (like that matters much) than 92 or 93 with ethanol. I've always used BP's 93 in the past but on the recommendations of this forum members, it's non-oxy 91 this year if it ever warms up. Link to comment Share on other sites More sharing options...
twobjshelbys Posted March 26, 2014 Report Share Posted March 26, 2014 How are you using your car? If you're just driving it on the street use whatever is recommended in your owners manual. (I think it was 89, sea level, that would be 87 in mountain areas - mid grade). If you are tracking the car go up a grade. I ran mine on 89 with the GT/SC Kenne Bell and it did fine. Never a ping. Remember that the engine control unit will compensate if you start to get any knock. Link to comment Share on other sites More sharing options...
Larry T Posted March 26, 2014 Report Share Posted March 26, 2014 I use Ultra 94 here in Canada .... best I have found without using race fuel. Link to comment Share on other sites More sharing options...
twobjshelbys Posted March 26, 2014 Report Share Posted March 26, 2014 Octane alone does not help mileage. If you can fine "real gas" (without ethanol) it will typically have a higher octane rating, but that is not what makes the mileage better; Alcohol in fuel, no matter how much, any amount greater than zero, reduces the energy content of the volume and thus reduces MPG. The fact is that almost all no-alcohol gas happens to be aircraft or watercraft fuel, and thus has a higher octane along with the no alcohol. Just FYI, E85 fuels tend to have an octane rating of somewhere north of 100. That means about a 20% reduction in MPG because it uses more volume to produce the same energy (thus the reason that E85 conversions usually need beefier injectors) but dang, they sure don't ping much This a classic case of "how to lie with statistics". Oh for the days of gas from the 60s with lead and that evaporated on skin contact. I used it on the farm to get the grease off my hands after working on farm equipment. I'm sure I pulled in a whole bunch of lead and that might explain a lot !!! Link to comment Share on other sites More sharing options...
drzeeba Posted March 26, 2014 Author Report Share Posted March 26, 2014 Thanks for the info guys. Much appreciated. Link to comment Share on other sites More sharing options...
Doug_GT350 Posted March 26, 2014 Report Share Posted March 26, 2014 FWIW, When mine was upgraded to the GT/SC they added a sticker to the gas cap stating 91 octane must be used. I usually use 93, because of what's available around here (87,89 or 93). As Tony stated the knock sensors will help if you need them. That being said I wouldn't use less than 91 unless I absolutely had to! Everytime someone asks me about gas mileage I just laugh and tell them "when you're driving a supercharged car the last thing you worry about is your mileage". Followed by "besides it's had to tell mileage with a Hybrid....... it burns gas and rubber!" Link to comment Share on other sites More sharing options...
AstroDan Posted May 13, 2014 Report Share Posted May 13, 2014 What octane do you use? It's almost impossible to find anything above 91 around here. It's either that or 109 that I found at one spot. Everything I see recommends 92 or better. What additive do you recommend? Can you have too much octane?What is your car? Since this is the GT/SC board, I'll assume that is what you own, in which case you should use (at least) 91. All said above about E85, 80/20 is true. there is a change here in California when going to the "summer blend" gasolines. The stock compression ratio on the Shelby GT is, I think, 10.1-1. That is certainly high enough to get the full effect of premium gas. I've NEVER put less than 91 in my car, including before the SC conversion. (I use Chevron 91) FWIW, I work in a large Bay Area Refinery with decades of experience... Link to comment Share on other sites More sharing options...
drzeeba Posted May 14, 2014 Author Report Share Posted May 14, 2014 My 08 SGT vert. is waiting in line at SAI for SC package and other goodies. When I don't have my Shelby available for therapy my mind wanders to when I will have her back! Thanks! Link to comment Share on other sites More sharing options...
springer Posted May 15, 2014 Report Share Posted May 15, 2014 As another wrote, the GT/SC has a sticker inside of the fuel door which reads 91 octane recommended. Burn what you want, but that is what is recommended - I use it in my GT/SC convertible. Link to comment Share on other sites More sharing options...
07SGT Posted June 7, 2014 Report Share Posted June 7, 2014 MY NA SGT has a sticker stating to use 91 octane. If I remember correctly isn't the 91 required due to the FRPP tune with the CAI, etc? Link to comment Share on other sites More sharing options...
HARALD KELLEY Posted June 7, 2014 Report Share Posted June 7, 2014 yes Link to comment Share on other sites More sharing options...
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