Re: 1937 120 Conv. Sedan - Blanche

Posted by TxGoat On 2024/5/16 7:52:44

High octane fuel is not needed for pre-war cars, but it will do no harm. Staying away from ethanol-adulterated fuel is a good idea, especially for cars that are not driven regularly. High octane fuel will behave the same as regular fuel under most conditions, but it will resist detonation under high load (heat and pressure) conditions better. Those extreme conditions don't occur in normal operation of pre-war engines, so high octane fuel is not needed. Hardened valve seat inserts are not needed in pre-war cars, unless you regularly run the engine at high loads and high speeds. Leaded fuel will do no harm, but it is not required in most cases. Even "high compression" engines will run just fine on low octane fuel, * IF * high load operation is avoided. All carbureted gasoline engines are "low compression" when operating at idle and part throttle, due to higher manifold vacuum (lower manifold pressure) under these conditions. Initial compression pressures are much lower at part throttle operation, and maximum combustion heat and pressure is much lower than at wide open throttle.

Ethanol actually has a high octane equivalency, but it only has about half the BTU content (fuel value) of motor gasoline, and it "spoils". It can decay and destroy fuel systems, and it will reduce power output at higher blends. A 10% ethanol blend might be expected to reduce maximum engine power and mileage by 3 to 5% compared to straight gasoline of good quality. Blends over 10% are known to cause a number of problems in systems not specifically designed for them. In my opinion, burning food in a hungry world is beyond absurd. Beyond that, the true price of ethanol as produced in the USA is very high. There are no net benefits to using corn-based ethanol as motor fuel.