An engine design having to tolerate detonation with a gasoline/air mixture is a completely different world compared to detonation of a methanol/air mixture. Actually, methanol really doesn't detonate in the way gasoline does. You can have varying intensities of detonation with gasoline. Not so with methanol. A more proper term for a methanol/air mixture that goes into uncontrolled combustion would be preignition. A preignition condition with gasoline would more closely match what happens with a methanol/air mixture when it goes into an autoignition condition.
Preignition compared to simple detonation is a much more intense and destructive form of uncontrolled combustion. Where detonation is understood to occur after the spark plug has initiated combustion of the mixture, preignition occurs at any given time before the spark plug has attempted to initiate the combustion event. It would be like the complete intake charge spontaneously combusting with a very quick flame speed and pressure rise, at a number of crankshaft degrees added to your planned ignition advance. Basically, this causes the cylinder pressure peak to occur much too early and attempts to stop the crankshaft and cause it to turn in the opposite direction of rotation. Obviously, head gaskets, pistons, rods and the crankshaft don't like this much and one or the other will exit the scene, stage right.
This is the main reason why knock sensors are useless with methanol fuel. If the knock sensor goes off, 9 times out of 10, it's too late.
Knock sensors should never be mentioned in a discussion involving the burning of methanol fuel. If one relies on a knock sensor when burning methanol, he will learn real quick not to.
Any form or level of detonation with methanol fuel involved should be avoided at all costs.
Preignition compared to simple detonation is a much more intense and destructive form of uncontrolled combustion. Where detonation is understood to occur after the spark plug has initiated combustion of the mixture, preignition occurs at any given time before the spark plug has attempted to initiate the combustion event. It would be like the complete intake charge spontaneously combusting with a very quick flame speed and pressure rise, at a number of crankshaft degrees added to your planned ignition advance. Basically, this causes the cylinder pressure peak to occur much too early and attempts to stop the crankshaft and cause it to turn in the opposite direction of rotation. Obviously, head gaskets, pistons, rods and the crankshaft don't like this much and one or the other will exit the scene, stage right.
This is the main reason why knock sensors are useless with methanol fuel. If the knock sensor goes off, 9 times out of 10, it's too late.
Knock sensors should never be mentioned in a discussion involving the burning of methanol fuel. If one relies on a knock sensor when burning methanol, he will learn real quick not to.
Any form or level of detonation with methanol fuel involved should be avoided at all costs.
