I`ve been running VP-100 and 101 unleaded fuels for 3+ years now and noticed the timing needs are slightly different from this compared to say 110 leaded and was curious for those w/a dyno or those that have dynoed different fuels how they differ on the egt`s. I would ASSume the unleaded burns hotter but not sure so what have you guys found.............Thankxxx
As said, not too many guys running individual thermocouples for EGT data anymore - for the reasons stated ( 02 info ). I run Sunoco 110 leaded pump race gas because 1. their use description fits my application. 2. It's less expensive than buying fuel at the track. 3. fuel at the track isn't always available. 4. Not much interested in lugging a 5 gal can of fuel around the pit area.
Sunoco 100 ( unleaded ) is also available at the same station where I get my 110 for the same price. From what I have seen, combustion chamber temps are pretty much in the range that Mr P stated. FWIW, looking at the specs of the 2 mentioned fuels, unleaded 100 has a BTU / gallon of 109200 while 110 leaded has a BTU/gallon of 113400. Sooo, it appears that 110 leaded puts out more heat than 100 unleaded ( which also BTW, contains 9.8% ethanol ). Conclusion = I have no idea? For sure, a change in fuels would warrant a change in timing. As you said Dom, dyno info.
I have been retailing race fuel for like 25 years, sell Sunoco.
Have never seen any kind of spec sheet that show what the EGTs should be.
I don't recommend blending fuels because it can affect consistency, maybe that is not concern of yours? Plus its a major hassle. For a street car, I guess no big deal but sure would make it harder to tune.
We sold both Sunoco fuels too at the pump, 110 leaded and 100 octane unleaded...with a ton of ethanol in it. Like said. I don't know about you, but I would not want ethanol in my performance gas.
We did not sell much 100 octane unleaded, we sell tons of 110 leaded out of the pump plus we stock many other grades in 54 gallon drums.
This past spring I took out the 100 octane unleaded and started selling 91 octane straight unleaded with no ethanol. This would be the gas to blend, with no ethanol. We have many street customers do just that. Buy a little of both and put it right into there muscle car at the pump.
We have sold way more of that gas so far this year than we did 100 octane all last year, like 4 times as much so far. It's popular for small engines and classic cars. It stores well and will last for years, try that with 100 octane with tons of ethanol in it.
And yup 110 leaded has more btus than unleaded so it will make more power(heat) than unleaded just because of the BTUs. I don't think it would change how hot your car runs, that's done by richer or leaner. You could easier make the "hotter" fuel burn cooler just by adding more fuel to the engine.
