diffrence between short runner intake and long runner intake

serg · 01-14-2001, 03:01 PM

for example performer intake short runner and trick flow long runner. wats diffrence wats better?

MiracleMax · 01-14-2001, 06:01 PM

That depends on what your after? Long runner intakes are for the most part better used for low rpm operation, where as short runner intakes are better for high rpm operation. Thats really a super over simplication of the matter.

Intake runners are designed to take advantage of resonant tuning by using a series of pulses which occur in the manifold.
To get a rough idea of where the resonant tuning takes place determine the rpm at which the resonant tuning occurs using the approximations below. then compare them to the runner lengths.for example plug in 6000 rpm for each one

2nd Pulse Length: 108,000/rpm (18 inches)
3rd Pulse Length: 97,000/rpm (16 inches)
4th Pulse Length: 74,000/rpm (12 inches)
5th Pulse Length: 54,000/rpm ( 9 inches)

If you match engine components then this provides a slight super-charging effect. However eahc pulse is progressively weaker but provides a broader powerband. If I remeber correctly most manifolds are designed to take advantage of the 3rd pulse because the lower pulses tend create manifolds to long in length to be practical (especially carb manifolds)

S Howard · 01-14-2001, 07:12 PM

Check out the last two issues--I think perhaps a little older--issues of MM&FF. The editors did a dyno comparasion test of the comp poly upper.

01-14-2001, 03:01 PM	#1
serg Registered Member Join Date: Jul 2000 Location: junction city ks usa Posts: 29	diffrence between short runner intake and long runner intake for example performer intake short runner and trick flow long runner. wats diffrence wats better?

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01-14-2001, 06:01 PM	#2
MiracleMax Registered Member Join Date: Apr 1999 Location: Hayes, Va, USA Posts: 798	That depends on what your after? Long runner intakes are for the most part better used for low rpm operation, where as short runner intakes are better for high rpm operation. Thats really a super over simplication of the matter. Intake runners are designed to take advantage of resonant tuning by using a series of pulses which occur in the manifold. To get a rough idea of where the resonant tuning takes place determine the rpm at which the resonant tuning occurs using the approximations below. then compare them to the runner lengths.for example plug in 6000 rpm for each one 2nd Pulse Length: 108,000/rpm (18 inches) 3rd Pulse Length: 97,000/rpm (16 inches) 4th Pulse Length: 74,000/rpm (12 inches) 5th Pulse Length: 54,000/rpm ( 9 inches) If you match engine components then this provides a slight super-charging effect. However eahc pulse is progressively weaker but provides a broader powerband. If I remeber correctly most manifolds are designed to take advantage of the 3rd pulse because the lower pulses tend create manifolds to long in length to be practical (especially carb manifolds)

01-14-2001, 07:12 PM	#3
S Howard Registered Member Join Date: Jun 2000 Location: Orlando, FL Posts: 195	Check out the last two issues--I think perhaps a little older--issues of MM&FF. The editors did a dyno comparasion test of the comp poly upper.