I'm in no way a chemist but I KNOW WHAT I did/do and works and don't appreciate your GOT LUCKY comment.
Mid racer at best???????????????.............lm
A hot running two stroke may well reduce it's EGT with a race gas, but it has to be the right gas. Sounds like LM got lucky that time.
teazer wrote:It's an old thread, but many questions were left unanswered.
100ll is designed to burn slowly in a slow running aircraft engine. The old myth about it being good for performance came back in the 50s when gas was about 80 octane and compressions were low. The car guys wanted more compression and that caused detonation, so if they were able to beg borrow or steal some av gas they could run a higher compression without meltdown.
So higher compression was the power generator. Av-Gas allowed them to use it.
We found on the dyno that 89 octane made marginally more power than VP C12 with a smoother power curve - that was on a full race CB160 turning 11,500 with raised compression.
Some race gas burn faster than others and a faster burning gas will have more burned before it leaves the exhaust port. Others are slower burning. Some have a low evaporation curve and some don't evaporate until at least 100 degrees higher.
All the gas is not used before it exits the port. Poor atomization and non effective squish mean that some of the larger fuel droplets are still burning as the gas goes down the pipe.
A hot running two stroke may well reduce it's EGT with a race gas, but it has to be the right gas. Sounds like LM got lucky that time.
Any more octane than a motor needs to avoid detonation is a complete waste of time and money and usually results in less power and a lighter wallet.
The only thing I really like about leaded race gas is that it tends to burn cleaner than unleaded and needs a cooler spark plug which is much easier to read at the race track. Unleaded tends to leave a sooty deposit and often needs a hotter running plug to keep clean.
Ethanol and methanol are hard on fuel systems, but we don't have rubber tipped float needles, or galvanized fuel lines, so that is less of an issue. Ethanol will leach the resin out a fiberglass tank though.
E85 is a whole different story though. It generally needs larger jets, more spark advance and can stand much higher compression. Alcohols generally need to be jetted differently than gasolines.