Posted by RDavis on Monday, February 02, 2004 at 11:16PM :
In Reply to: Lead/No-Lead Fuel posted by dave horvath on Monday, February 02, 2004 at 1:02PM :
Contrary to somethings that have been said about leaded gasoline, I have vintage books that give the straight facts and they all say the same thing.
First lead was not originally intended as a lubricant for valves or any other engine part. It was "discovered after the fact" that the micro film left on the valves and seats had a dampening effect on the force of the valve snapping shut onto the seat and somewhat helped the seal as the valves and seats wore.
The black deposits found in engines was carbon deposits not lead. Too rich or inefficient burning a mixture left more carbon deposits.
Lead was originally used then and up until it was elimanated as a octane booster or additive. Octane is a rating, not a substance. A rating like horse-power & torque. It is a rating of the burning characteristics of a distilled batch of gasoline. Lead was used to boost the octane rating of a batch if it tested to have too low a octane rating to run efficiently in a test engine using a average compression ratio of current engines.
Low compression engines like flat-heads can use low octane fuels effectively as where a high compression engine like those used in race cars and aircraft require a high octane rated fuel. A high octane rating does not mean the fuel is more "powerful" but, that it is very stable at very high compression although other additives like nitro-methane make it more "powerful".
Follow Ups: