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Better Performance With 93 Octane


TRTGT500

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So my dealer filled my car with 91 octane, I think...they are pretty frugal ,when I picke up the car last Friday. I filled up today with Sunoco 93 and drove to my cottage, 200 mile round trip. I get off the expressway and notice a bit more supercharger wine (i like!) and the car seems to pull stronger and sound better. Is it my wishful thinking or is this car that smart? It only has 650 miles on it so far, does the computer gradually adjust boost until it gets more miles on it? In any event the car continues to amaze me! :worship:

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It might depend on whether your 91 octane is oxygenated or non-oxygenated. There is quite a bit on this subject by some folks much more knowledgable about octane and ethanol. But from what I understand, 91 octane IF non-oxygenated, is a better fuelthat burns cleaner and provides better performance than 93 or 91 oxygenated fuel Of course, non-oxy 91 is quite a bit more expensive.

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I thought all our cars required 93 or higher octane?

I thought all our cars required 93 or higher octane?

I have had both of the 500s tuned for 91. Sure you loose some hp but who knows what is really coming out of the pump in some little town or how old the gas is. Better safe than BOOM

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Driving to work this morning I can for sure feel and hear a difference in my motor, must be the better gas, who knows my dealer might have put in 87 or 89! I can't get enough of the engine and exhaust sound, music to my ears!

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I test drove a GT500 before buying mine and we had to stop and get gas in it because it was on E and I can't be certain the clueless salesman put in premium. The car certainly didn't seem to pull as hard as mine did. Both were stock and this was a coupe which would have been lighter than my vert. I wonder if that thing was retarding timing like crazy trying to keep the engine together.

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BIllross:

 

I live in North Oaks, MN and I get my gas at the BP in Moundsview which sells non-oxy 91. You are right in that most sell only 91 with the exception of BP. I found a list onlline of non-oxy retailers throughout the state with some selling has high as 114 (can't imagine what that is per gallon). I haven't noticed any difference between the 91 and BP 93 but I did notice a diference (improvement) in the the non-oxy 91.

 

Enjoy your car, it's a beaut if the weather EVER gets better. Easter Sunday was perfect though.

 

Kevin

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When evaluating 91 vs. 93 it depends if the car was tuned for 93. If not, then a number of factors play into that sensation of added HP/TQ, such as air temperature, engine heat soak, air density, altitude, etc. Most western states do not have 93 at the pump so we look to speciality tuners to get as much as we can out of 91octane without risking the life of the engine. Fortunately Ford gave us a lot of room to tweak.

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Bill:

 

I have wrestled with this octane thing forever and there seems to be a ton of opinions on the subject. After reading all the comments on the matter on this forum by folks a lot more knowledgeable than I, the concensus seemed to be that yes, 91 non-oxygenated is better for the engine than 93 oxygenated as it burns cleaner and is better on the engine in general. However, the MPG goes down and the cost of the fuel goes up. I don't drive it much so the cost doesn't matter all that much. Since my car was tuned to 91 by KB, I asked them their thoughts as well and they said 91 non-oxygenated would be preferred but the 93 oxygenated will work just fine. It's almost like splitting hairs here.

 

Kevin

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Exactly. In fact, my car was tuned to 91 by KB and I asked them about whether I should have it re-tuned to 93 since I can get it rather easily. They told me the difference is minimal and not worth the re-tune.

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If you run too low of an octane fuel you will have combustion chamber detonation - which the PCM will sense through the engine knock sensors and retard (back off) the ignition timing. Less advance on the ignition timing = less HP and TQ. So you can run lower octane fuel and make less power but the knock sensors will protect the engine from damage. I think Ford states something like "optimum power achieved with premium fuel".

 

FWIW.

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  • 2 weeks later...

From the owners manual .

 

Premium unleaded gasoline with an
(R+M)/2 octane rating of 91 or
higher is required. SVT recommends
using unleaded gasoline with octane
rating of 93 or higher for optimal
performance of this vehicle.
Recommended fuel is an important part of the proper maintenance and
optimal performance of this vehicle. The use of gasoline with an octane
rating lower than 91 can lead to severe mechanical damage to your
vehicle, may degrade vehicle performance, and may affect your warranty

coverage

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