UNLEADED GAS

wa8yxm wrote:
What can happen is over time carbon deposits build up in the combustion chambers and you may start to hear a bit of "rattle" (Pre-ignition knock) which goes away if you upgrade the fuel to mid or premimum.

HOWEVER, this means you need service, MAJOR service.

Nah, just get the engine good a hot and mist water down the intake. When the water hits the cylinder head, it will boil the carbon off. Worked great on my first Goldwing.

One of the problems we have is the labeling of premuim vs regular. We associate the word "premium" with higher or more pure. In fact the opposite tends to be true. The octane rating is exclusively a measure of the ignition temperature. The lower octane means that it ignites easier. That is why an engine that is designed to run on regular will get worse mileage running on premium. Now it is true that from a design standpoint, raising the compression will squeak out more power, but when the compression is raised, the fuel may self ignite. High compression really is a trade off, but a good one, as the gains of the higher compression do outweigh the losses from being required to run gas that is harder to burn. The trick with more recent designs is fats burn heads, which compacts the fuel in one small area, as opposed to being spread out over the whole piston. This helps prevent self ignition and allows higher compression. For instance, the 8.1 liter BBC has higher compression than the old 454 could get away with, because of the head design.