Real World Solutions, Inc
Home of RA Classic Apex Seals and RA Super Seals
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It is strongly recommended that the Mazda oil bypass valve be disabled in all rotary engines used in aircraft. The purpose of this valve is to PREVENT oil from cooling the engine in the car until a minimum operating temperature has been reached. This was done in order to help meet the automobile EPA requirements. In an airplane we DO want to cool the engine at any and all operating temperatures, hence we disable the bypass valve. The most common method for disabling the valve is to install a spacer under the valve. The piston in the thermal pellet usually removed. Some builders choose to install the Racing Beat drive pulley (smaller diameter than the stock pulley) on the crank to slow down the water pump and alternator. Changing this pulley will affect the position of the oil bypass valve because the Racing Beat part does not allow the large bolt which attaches the pulley to the engine to seat as far into the crankshaft as the stock pulley. If the oil bypass valve spacer was made to fit the stock pulley before changing to the Racing Beat pulley, the bypass valve will be in the incorrect position due to differences between the stock pulley and the aftermarket pulley. This results in LOW OIL PRESSURE (very similar to the symptom that you would see if you have a blown out O-ring in the front cover). The problem has shown up on at least three flying rotary engines so far. IF YOU EXPERIENCE LOW OIL PRESSURE ON A NEWLY BUILT ENGINE, BE SURE TO CHECK THIS AS A POSSIBILITY. The proper length of the oil bypass valve spacer when using the stock pulley is .400". If using the Racing Beat pulley, the spacer should be .600" long. Note that the actuating pin should be removed from the bypass valve unless the spacer is hollow. See "Aviator's Guide to Mazda Rotary Conversion" book for further details. |
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