Quote:
Originally Posted by RedBarchetta
Aren't you describing the procedure for optimizing the torque curve just aft of a header collector? Old drag racing tuning trick. Not sure how lengthening or reducing the straight pipe affects harmonics? I should have paid more attention in HS physics class. 
There is definitely some level of turbulence that is causing the flap. But, again, only on deceleration and usually more prevalent below 2,000 rpm. Might be air crashing together under engine braking?
-Dean |
could you be thinking of crossover tube placement?
my jbl has the sound you're talking about also when cold sitting still, don't know if it is the cold clearance on the solid rollers or what. i think it is the sound of reversion though. here is some data from a program that figures the length of pipe, hth.
---- Primary Pipe's Harmonics ----
1st Harmonic = 131.8 inches long ... typically never used
2nd Harmonic = 50.0 inches long ... longest recommended
3rd Harmonic = 29.9 inches long ... highly recommended , best Torque Curve
4th Harmonic = 20.8 inches long ... shortest recommended
5th Harmonic = 15.7 inches long ... typically never used
6th Harmonic = 12.3 inches long ... typically never used
7th Harmonic = 10.0 inches long ... typically never used
8th Harmonic = 8.3 inches long ... typically never used
---- Collector's Harmonics (includes Intermediate, Muffler , TailPipe) ----
1st Harmonic = 137.5 inches long ... longest with Mufflers and TailPipes
2nd Harmonic = 68.7 inches long ... longest recommended with Mufflers
3rd Harmonic = 34.4 inches long ... more bottom-end Torque
4th Harmonic = 17.2 inches long ... highly recommended , best Torque Curve
5th Harmonic = 8.6 inches long ... reduced Torque , more top-end HP sometimes
6th Harmonic = 4.3 inches long ... reduced Torque , not recommended