Tetraethyl lead was added to motor fuels, both automotive and aviation to raise their octane number for the purpose of preventing pre-ignition. A side benefit of lead in motor fuel is that it acts as a cushion for valve seats and valves. In older engines the valve seats were not hardened as the lead in the fuel prevented valve recession.
Once lead was removed from most motor fuel, valve recession became a genuine issue for land vehicles used in high power demand situations, such as racing, construction and farming equipment, etc...
The Time Between Overhaul specs for piston aero engines has not changed basically because most piston aero engines are very old designs. Current governmental regulations, especially here in the US, really put a damper on development of new piston aero engines. So, the industry soldiers on with opposed cylinder air cooled engines that were all basically designed in the 1930s and 1940s.
If a new water cooled, small general aviation engine could be designed and built and more importantly, sold at an affordable price, it could be built to take advantage of all the innovations in piston engines and materials that have come along in recent times, and could have TBOs that are far longer than your common Lycoming or Continental.
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Personally speaking, the P-40 could contend on an equal footing with all the types of Messerschmitts, almost to the end of 1943.
~Nikolay Gerasimovitch Golodnikov
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08-05-2012, 03:25 PM
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