pie_row
Well-Known Member
Mark Langford's KR2S Project
This is a well written account of engine trouble on takeoff. He came to the conclusion that the problem was detonation. Reading what he wrote and taking it at face value the conclusion that I came to was that it was pre-ignition that caused the problem and not detonation. There was detonation to be sure but that was because of the advanced ignition caused by pre-ignition rather than the cause of the problem. Functionally the difference between pre-ignition and detonation doesn’t matter.
What he had was a hot spot. He found that on teardown. The hot spot can ignite the charge early. The early ignition then triggers detonation. The telling statement that he made was this, “I knew it was detonation because when I backed off the power I heard it.” Detonation goes away when you back off the power. Pre-ignition on the other hand goes away when the head cools off. He heard the detonation until the head cooled off. High temps can cause detonation as well but pre-ignition that was very likely what he had.
This is a well written account of engine trouble on takeoff. He came to the conclusion that the problem was detonation. Reading what he wrote and taking it at face value the conclusion that I came to was that it was pre-ignition that caused the problem and not detonation. There was detonation to be sure but that was because of the advanced ignition caused by pre-ignition rather than the cause of the problem. Functionally the difference between pre-ignition and detonation doesn’t matter.
What he had was a hot spot. He found that on teardown. The hot spot can ignite the charge early. The early ignition then triggers detonation. The telling statement that he made was this, “I knew it was detonation because when I backed off the power I heard it.” Detonation goes away when you back off the power. Pre-ignition on the other hand goes away when the head cools off. He heard the detonation until the head cooled off. High temps can cause detonation as well but pre-ignition that was very likely what he had.
