... Rotation Speed Range: 100~40,000RPM Rotation Speed Resolution: 1RPM GASOLINE ENGINE TACHOMETERSM8237Inductive type measure the engine speed by noncontactMeasuring the ... engine by contactTesting the rotate speed of multi-cylinder in same time,or testing one of cylinder rotate speed Testing the ... 3, 4, 5, 6, 8, 12 or set the impulse of each rotationMemory the maximum value, minimum value and last value ...