105 Octane Race Gas
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DakotaGT
GT Owner
If you plan on taking advantage of the increased octane, then yes. Otherwise, why would you run the 105? Wouldn't hurt to add a gallon or two to each fill up with 93 premium, just for a little protection in case the 93 is actually a tad lower than advertised, or if you plan to store the car for a while. But you won't see an increase in performance just from switching to 105. Also, make sure any race fuel you use is unleaded! O2 sensors and catalytic converters tend to get ruined in a hurry if you run leaded fuel.
Many forced induction cars employ knock sensors and the ECUs can advance timing until they see knock events. In such vehicles, you can run a higher grade of fuel and you may see some increased performance through advanced timing. But, the GTs do not use knock sensors and are going to blindly advance timing and fuel according to what's been programmed into the ECU. I agree with DakotaGT that higher octane is a nice thing to have in order to give you a little headroom against detonation, but you will not see any performance benefits until/unless you tune for the higher grade.
peiserg
GT Owner
twobjshelbys
GT Owner
(1) Unless you have a tune for 105 the extra octane only benefits the gasoline company
(2) E85 conversions are possible but pricey, and E85 is not readily available in all areas.
(3) It is highly likely we have the same GT guys setup. If so it came with a 103?/105 tune on the tuner. All you should have to do is reprogram it. Make sure you do it in the correct sequence: Empty the tank then fill with 103/105, and then switch the tune. It will not be healthy to run the new tune with 93 in the tank.
(4) Octane does not affect winter storage. Best to add some Stabil, or drive it every few weeks for a few miles to get it up to operating temp to keep oil and other fluids, esp. supercharger, flowing.
But why? For street driving 105 it won't matter. Different if you track your car.
(2) E85 conversions are possible but pricey, and E85 is not readily available in all areas.
(3) It is highly likely we have the same GT guys setup. If so it came with a 103?/105 tune on the tuner. All you should have to do is reprogram it. Make sure you do it in the correct sequence: Empty the tank then fill with 103/105, and then switch the tune. It will not be healthy to run the new tune with 93 in the tank.
(4) Octane does not affect winter storage. Best to add some Stabil, or drive it every few weeks for a few miles to get it up to operating temp to keep oil and other fluids, esp. supercharger, flowing.
But why? For street driving 105 it won't matter. Different if you track your car.
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DakotaGT
GT Owner
Octane drops over time. So, if your storage period is lengthy (like the November through May that my cars in SD are hibernating), having a few gallons of higher octane fuel in the tank will provide you with a measure of safety when you get the car out of storage. But agree otherwise, that it doesn't act as a "fuel stabilizer".
peiserg
GT Owner
I agree the e85 is slightly pricey... But to clarify, its injectors ($800 from torrie), a boostapump ($300 from torrie, used) and a tune. Thats it. Not complex. Yes, e85 availability is also a consideration. Im lucky... I have e85 1.3miles away.
twobjshelbys
GT Owner
Anyone driving a gt isn't probably concerned about gas mileage but with e85 expect a 25+% reduction in gas mileage. The other is is with predictability since the actual percentage of alcohol and thus the octane can vary wildely.
For Storage there is now a stabilized "race fuel" that can be bought from VP in 5 gallon cans.
The claim is 2 years stability and a guaranteed octane rating vs pump gas.
I think it's about 95 octane.
It's been out 2-3 years.
I forget the Designation on the can but I can come up with it if need be.
No issues so far.
Great for your carbureted vintage cars in particular.
The claim is 2 years stability and a guaranteed octane rating vs pump gas.
I think it's about 95 octane.
It's been out 2-3 years.
I forget the Designation on the can but I can come up with it if need be.
No issues so far.
Great for your carbureted vintage cars in particular.