Definition of acceleration

[SvilleKid]

Originally Posted by Sancho Fuente

The first part of that is actually pretty close to accurate. At 9,000 RPM the engine makes 150 full revolutions per second. Now you have to remember that in a traditional 4-stroke internal combustion engine each cylinder only has 1 combustion event every 2 revolutions. In a V8 a cylinder fires every 90 degrees of crank rotation, 720 degrees for all 8 cylinders to fire. So to make numbers easy, lets just say that the engine is at 9,000 RPM for a 4.00 sec pass.

9000/60 = 150 revolutions per second
150*4 = 600 engine revolutions if the engine is at 9,000 RPM for a 4.00 sec pass


Now for fun, the engine needs to spin 720 degrees for all 8 cylinders to fire, so from 600 revolutions there are 300 complete engine cycles (all 8 cylinders through all 4 strokes)
300 cycles/8 cylinders = 37.5 complete 4 stroke cycles per cylinder per pass
37.5 cycles at 4 sec is 9.375 complete 4 stroke cycles per cylinder per SECOND
If a 4 stroke cycle is finished at just about 100 milliseconds, that means the crank is spinning TWICE that since it take 2 full turns for 1 cycle. You are looking somewhere around the 50-75 milliseconds for the crank to make one complete revolution.

OOOWWWW! My head hurts!

Mind boggling. Is it any wonder they tear the engines all the way down and rebuild them after each run?