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.
