XR7 Dave

12-22-2006, 11:27 PM

After initiating this test it quickly became apparent that I needed to establish some testing standards and parameters to prevent skewing results and getting innaccurate results so that is why I had to re-do the test. The results have changed.

I realized in the first test that each port wasn't flowing the same in each manifold and I became concerned about exit angles for each tube and possible turbulence in the collectors. This led me to do two things.

1) I added a pipe extension to all collectors. The longtube Kooks already have an 8.5" x 3" collector on them so I extended that slightly to a total of 14" and I used that length on all tests. The other headers all have 2.25" oulets so I used a 2.5" extension on those and the manifolds (and 96 Bird header) all have < 2" outlets so I attached a 2.25" extension on them. I then tested the Kooks longtubes with a 2.5" reducer and tried the 95 Mustang header with both 2.25 and 2.5" pipes. In each case the flow difference at full lift was just .5cfm. Now is also the time to point out that in EVERY case adding the 14" extension improved flow!

2) I tested each pipe in each manifold. I blocked off the remaining 2 pipes when testing each one and the results are noted below. Some manifolds/headers definitely have better balance than others.

The results include flow at all points from .100-.450" lift on a totally stock cylinder head and are compared to a straight diffuser for a baseline. All tests were conducted consecutively on the same day for the sake of consistency. I also included the % variation between all ports and the gain or loss relative to the straight diffuser. This first test was embarked on specifically to show what flow advantage there might or might not be for each manifold/header on a stock engine.

I hope you find these results helpful. I will be performing tests on ported stock manifolds also but that will have to wait as I do not have the porting done at this point. I will update the test when I have that data.

I will also be doing another test on a fully ported set of heads at lifts up to .600" to give a better perspective of what potential these manifolds/headers have.

I realized in the first test that each port wasn't flowing the same in each manifold and I became concerned about exit angles for each tube and possible turbulence in the collectors. This led me to do two things.

1) I added a pipe extension to all collectors. The longtube Kooks already have an 8.5" x 3" collector on them so I extended that slightly to a total of 14" and I used that length on all tests. The other headers all have 2.25" oulets so I used a 2.5" extension on those and the manifolds (and 96 Bird header) all have < 2" outlets so I attached a 2.25" extension on them. I then tested the Kooks longtubes with a 2.5" reducer and tried the 95 Mustang header with both 2.25 and 2.5" pipes. In each case the flow difference at full lift was just .5cfm. Now is also the time to point out that in EVERY case adding the 14" extension improved flow!

2) I tested each pipe in each manifold. I blocked off the remaining 2 pipes when testing each one and the results are noted below. Some manifolds/headers definitely have better balance than others.

The results include flow at all points from .100-.450" lift on a totally stock cylinder head and are compared to a straight diffuser for a baseline. All tests were conducted consecutively on the same day for the sake of consistency. I also included the % variation between all ports and the gain or loss relative to the straight diffuser. This first test was embarked on specifically to show what flow advantage there might or might not be for each manifold/header on a stock engine.

I hope you find these results helpful. I will be performing tests on ported stock manifolds also but that will have to wait as I do not have the porting done at this point. I will update the test when I have that data.

I will also be doing another test on a fully ported set of heads at lifts up to .600" to give a better perspective of what potential these manifolds/headers have.