Using V = 1100ft/sec the equations simplifies toĤ000rpm peak boost requires 33" tubes!! That length includes the ports in the heads. For cool intake air it is about 1100ft/sec Values of 1300ft/sec to 1700 ft/sec are common. L = pipe length, less port length in head, in inches Thus tuning length is very easy to determine once you have an estimate of the speed of sound in the hot gasses (or cold gasses for intakes). Other pulses from other header tubes are of much smaller magnitude in the tube of interest and can be ignored. You want this positive pressure pulse to reach the intake valve the instant it closes to supercharge the cylinder. Obviously, the opposite is true for intake manifolds - the opening intake valve causes a negative pressure pulse to travel up the intake runner and a positive pulse is reflected back down the tube. The main advantage gained in equal length, independent primary header tubes is from the strong negative pressure pulse that is reflected from the tube end when the strong positive pressure pulse from the exhaust valve reaches the collector. Injector stacks have an infinite 'plenum' - the atmosphere!) is reasonably larger than the primary tubes, each tube acts independently from its neighbors. Read these old threads.Īssuming the (exhaust) collector size (or carb plenum. If any of you have input on this, I would appreciate it greatly. But I'm curious to know what you all think. My engine guy says to make them the same length as the ones that came from Hilborn. I'm guessing that the optimum velocity stack length varies by application, and the only way to know what's best is by trial and error on the dyno. Not sure on the cam specs, or if any of this info is relevant. The engine is limited to 6250 RPM, and will rarely if ever see more than 4500 RPM. Now, I'm making custom curved velocity stacks, and I'm wondering if I'd gain anything by making them a little longer. My engine builder said that when the previous stacks were cut-down from their stock length to fit under the hood, we threw away 40 ft-lbs of torque. I'm looking for opinions regarding the optimum length for a Hilborn EFI fuel injector velocity stack.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |