00gstang

high compression engines require higher octane, that's a no brainer. 87 octane is crap. why do you think all of the high compression/boosting engines use high octane fuel? to prevent detonation! i don't care what you say, the more compression/advance you have, the higher octane is needed. just because your engine doesn't ping doesn't mean it's not suffering with low octane gas and advanced timing. adding water wetter is not going to save your engine from detonation.

ymeski56

Your confusing high Compression w/ rate of compression. A certain amount of extra quench effect of a slight increase in octane's ok for a low compression engine w/ an increased rate of compression (timing bump). But 91 octane is overboard.

Eventually after running 91 for a while, you'll fine it will have to run 91 octane in order not to ping. I'm not, nor have I said this of high compression engines. Thats a different story, & these engines are what higher octanes were designed for. But modding the timing of a low compression does not itself, make it a high compression engine!

At 16 BTDC, a 60K volt coil, my sidegap plugs gapped .012 wider than stock, will barely start w/ 91 octane. But it likes 87 just fine.

The Octane level choice depends on the intended use. 87 & 91 are just different formulas. 87 is in greater demand so more is made, therefore cheaper. That doesn't make it "crap"!

Wetter Wetter helps increase the thermal transfer properties of the coolant system. So does descaling the engine. De-sludging your engine by itself won't eliminate ping. Neither will a 180 thermostat, but they all add up to controlling combustion chamber temps. collectively, to remain below Ping threshold.