This is a subject that can drive ya nuts. All the fuels on the market today are lead free. Also, there are many additives that different gasoline companies are putting in to either help the environment, or cheaply boost the octane rating. The higher the compression ratios you have, the better the fuel needs to be. Sorry to say, the fuels aren’t making the trip. On my engines I am running 6.8-1 and can run high octane water.
If you are running an engine with a CR of more than 7.5 to 1 as a daily driver, especially in the hot weather, then you may be heading for problems-particularly vapor lock. Here in Idaho, most stations have stickers on the pumps stating the fuel isn’t more than 10% ethanol. The problem is ethanol raises the octane rating, but lowers the boiling point (see Tech article ETHANOL). It’s a great combination for vapor lock on your air-cooled engine! In the summer in Idaho, where temps can reach 107°, you can see a lot of cars on the side of the roads trying to cool down — and they’re not just Air-Cooled VWs either.
We have also experienced situations where some stations in the smaller towns sold 85 Regular as 89 Premium. This is 85 out of the 89 pump, at the 89 price. There is a good tool available to the everyday driver called a fuel tester. It tells the percentage of ethanol in the fuel. We carry them with us. So here is my problem: it’s great when you are running 32 degrees max advance, and are on actual 89 octane. Then you get up the road and gas up again with 89 (so the pump says…), and it sounds like the pistons are swapping holes back there behind you. We then have to stop and retard the timing to continue on our way.
At one point, California was mandating the use of ether in their fuels to help clean the environment. It was a product called MTBE. A few years back they found it was contaminating the environment, and was getting into the water supply, aka the aquifer. They still don’t have a good way to remove it from the groundwater. As of September 2005, twenty-five states have enacted legislation that bans the use of MTBE. The point is government bureaucrats will enact anything to appear like they are making the ENVIRONMENT better. This includes putting crap like ethanol and ether into our fuels.
I don’t know if they will ever come up with a decent fuel in the future. I just use the best I can find and watch the timing and listen to what the engine is saying to me on the road with a strange diet. Anymore, I just run the premium fuel and live with it till the vapor-lock starts. I then turn on the electric pump and keep on moving.
– Mike Humeston