Flow testing headers and manifolds about to begin

Which header do you think will flow the best?

  • Ported Stock Manifold

    Votes: 6 8.7%

  • 95 Mustang Header

    Votes: 6 8.7%

  • 96 T-Bird Header

    Votes: 1 1.4%

  • Mac Shorty

    Votes: 11 15.9%

  • Kooks Mid Length

    Votes: 25 36.2%

  • Kooks Long Tube

    Votes: 28 40.6%
  • Total voters
    69
  • Poll closed .
XR7 Dave

XR7 Dave

Registered User
I'm almost ready to begin flow testing these things. There will be 2 tests.

The first test will be done with a stock head, stock valve, and will be tested up to .450" lift. This test will be done to show any flow advantage on a stock motor.

Then the 2nd test will be done on an exhaust port that flows +200cfm and will be tested at .500 lift and at .600" lift.

Baseline tests will be run with a straight 1.6" ID diffuser for comparison.

For testing we will have:

Stock 89 manifold
Stock 95 manifold
Ported 89 manifold
Ported 95 manifold

Ported 96 Tbird header, 1 1/2" primaries with 1 7/8 collector
Stock 95 Mustang header,

Mac shorty header, 1 5/8" primaries with 2 1/4" collector
Kooks mid length header, 1 3/4" primaries with 2 1/4" collector
Kooks long tube header, 1 3/4" primaries with 3" collector

I will post pics of each as I get them. The last ones to arrive will be the 95 Mustang headers this weekend.

In the mean time I want some votes to see what people think will work best. Vote 3 times for your #1 pick, 2 times for your #2 and vote once for your #3 pick. Please only enter one set of votes. :)
 
Thanks for going through the trouble of doing it! Now us broke people will know what we're getting with our "cheap" fix! :)
 
Neither do I. It didn't work out how I thought it would. Oh well, this isn't a scientific research study as it were. :rolleyes:
 
cool Dave, this will be interesting. In the Mustang world we don't find any real improvement by switching fromt eh stock shorty header to a MAC shorty, so I don't see a huge difference there, at least in worthwhile inprovment to justify buying MAC, but I think the stock Mustang headers will show the best bang for the buck in terms of flow/price comparison. Looking forward to seeing the results.
 
Well, it better be the ported stock manifold because my down tubes are brand new and I don't think I want to have go out and buy a set of headers :D

Ira
 
i know it's more complex than this, but i voted for the long tubes over the mid length because the combined cross sectional area of 1.75" primaries is far bigger than the cross sectional area of a 2.25". 3" still has less, but perhaps the slight increase in exhaust gas velocity will help or something.
 
I voted for mid-length. I thought they were 2.5" collectors?

Are the mac headers a direct bolt in? No welding needed?
 
Remember that we only flow one tube at a time. Also, remember that when the engine is running only one cylinder is exhausting at a time. You don't want or need a collector that adds up to the sum of all 3 primary tubes.

I think the mid length Kooks will flow the best. Keep in mind that flow is only one aspect of header performance. I'm doing this test to try to determine if there are some really bad choices out there, not to determine what is the best because like I said, flow is only one part of the equation.
 
I voted for long tubes to flow the best, but I don't really think they are needed to keep up with flow from the current heads and intake manifold.

David
 
XR7 Dave said:
Remember that we only flow one tube at a time. Also, remember that when the engine is running only one cylinder is exhausting at a time. You don't want or need a collector that adds up to the sum of all 3 primary tubes.

I think the mid length Kooks will flow the best. Keep in mind that flow is only one aspect of header performance. I'm doing this test to try to determine if there are some really bad choices out there, not to determine what is the best because like I said, flow is only one part of the equation.
Click to expand...

In a four cyl only one is exhausting at a time. But if you break it down, each revolution has 3 exhaust strokes/cyls right?

Chris
 
If you're doing flow testing with exhaust manifolds and headers, it will all determine on the length of the tubing. Since the Shorties are tubular and short, then it is going to flow more than anything else that is substantially longer. I accidentally voted for ported stock, but I really want it to be the shorty because I didn't see it until after I voted.
 
David Neibert said:
I voted for long tubes to flow the best, but I don't really think they are needed to keep up with flow from the current heads and intake manifold.

David
Click to expand...

x 2. I remember XR7 Dave's cougar almost bottoming out with those installed on the car.
 
CMac89 said:
If you're doing flow testing with exhaust manifolds and headers, it will all determine on the length of the tubing.
Click to expand...

Thats true...I didn't think about head loss from longer pipes. In reality though air has virtually no viscosity, and fairly low density, I don't see the extra foot or so making all that much of a difference.
 
seawalkersee said:
In a four cyl only one is exhausting at a time. But if you break it down, each revolution has 3 exhaust strokes/cyls right?

Chris
Click to expand...

:confused:

One complete cycle on our engines is 720 crankshaft degrees. 720/6=120. One exhaust pulse per 120 deg crankshaft rotation. Our engines are even fire and the banks are split with only 3 on one side so that means on each side of the motor there are 240 deg rotation between exhaust pulses. Since no one runs a cam with more than 240 deg duration, it follows that there is never more than one exhaust valve open at a time per header.

That is also why our cars sound so obnoxious. There is no exhaust pulse cancelation and since no two cylinders run exactly opposing cycles, joining the exhaust via a crossover tube doesn't help much either.
 
XR7 Dave said:
:confused:

One complete cycle on our engines is 720 crankshaft degrees. 720/6=120. One exhaust pulse per 120 deg crankshaft rotation. Our engines are even fire and the banks are split with only 3 on one side so that means on each side of the motor there are 240 deg rotation between exhaust pulses. Since no one runs a cam with more than 240 deg duration, it follows that there is never more than one exhaust valve open at a time per header.

That is also why our cars sound so obnoxious. There is no exhaust pulse cancelation and since no two cylinders run exactly opposing cycles, joining the exhaust via a crossover tube doesn't help much either.
Click to expand...

So a by-product of this test may also be a better sounding exhaust?? :confused:

Ira
 
I think its great your going thru with such a large test, with no cash flow for you when your done.

I hope to hears its the kooks, I have a set for both my SC's now. Hope that wasn't money poorly spent.

Looking forward to see how much more the ported stock manifolds out perform(if at all) the stockers.

Good luck with this dave.
 
Ryan A Harris said:
I think its great your going thru with such a large test, with no cash flow for you when your done.

I hope to hears its the kooks, I have a set for both my SC's now. Hope that wasn't money poorly spent.

Looking forward to see how much more the ported stock manifolds out perform(if at all) the stockers.

Good luck with this dave.
Click to expand...

Ryan,

What 'kooks" do you have ...... medium or long tube ?

David
 
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