Quote:
Originally Posted by brn12345
I agree that 2 odd degrees on just two cylinders might not make a world of a difference, but I do have a theory that I want to test out.
1. I have a hunch the stock map pulls timing in the 1/2 cylinders not because they are detonation prone.
2. When I changed to headers I measured the stock header primary's and noticed that 1/2 primaries are shorter than 3/4.
3. I installed Equal length headers.
So my theory is that the timing retard on 1/2 is there for pulse tuning purposes and since I moved to equal length that now the pulses are out of sync. I went ahead and zeroed out the tables and will be testing tonight to see the difference.
Does this make sense or am I just theorizing too much?
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This is an interesting thought. At 6000 rpm the engine will rotate through 2 degrees in
6000 rotation/min * (1/60) min/sec * 360 degree/rotation = 36000 degree/sec
2 degrees / (36000 degree/sec) = 55 * 10^-6 seconds
Assuming the speed of sound is close to the speed of sound at sea level, the distance the exhaust pulse would travel in that time:
55*10^-6 seconds * 343 m/s = ~ 2 cm
I am making a lot of huge assumptions about systems that I don't fully understand so this could be way off, but my back of the envelope calculation and basic understanding say your theory is feasible. One thing to note, however, is that if their only goal with that timing table was to match up exhaust pulses then the timing retard should increase linearly with engine speed.