What impact does the unleaded fuel have on the performance, horsepower and durability of the engine?
The performance of the engine is affected in only one significant way. The loss of tetraethyl lead dictates that unleaded fuel must use alternate chemical compounds to raise the octane rating of the fuel to an acceptable level. The new unleaded fuel has an octane rating of 98, whereas the older leaded fuel has a 112 rating. The octane number is a measure of a fuel’s resistance to the phenomenon of detonation. Detonation is the premature ignition of the fuel air mixture in the engine’s combustion chambers and it is an extremely destructive force. As a result the engine must be tuned for absolutely precise air-fuel ratio and spark timing. The horsepower production is unaltered by the fuel change. This is due to the energy content of the fuel being unchanged. Hydrocarbon fuels measure energy content in BTU/lb.(British Thermal Units per pound of fuel) The value for both fuels is approximately 18,000 BTU/lb. Because each fuel contains the same amount of chemical energy, each is capable of t
