[ta man]

Originally Posted by Steve C.

Regarding the primary pipe diameter for your street/STRIP application your bias should be toward making more top end while sacrificing a LITTLE down low.

Also note if your cylinder heads are ported to 315 on the intake and the exhaust port is left untouched the exhaust-to-intake flow ratio will only be about 58 percent. This based at 0.600" lift. Due to the amount of energy (heat) lost during the combustion process, a basic ratio of 75 to 80% exhaust flow/size to intake flow/size is a viable target. And yet some suggest exhaust port flow numbers are about useless in the real world.

Also if left at 58 percent some will suggest adding additional exhaust duration on the cam choice.

Do your homework on the subject.
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Going from my flow numbers on my heads SD is right at 75% after port work. At .400 272.2/205.3 75.42% at .500 300.6/226 75.18%

[78w72]

Originally Posted by ta man

Going from my flow numbers on my heads SD is right at 75% after port work. At .400 272.2/205.3 75.42% at .500 300.6/226 75.18%

youre using 1 3/4 headers right?

[ta man]

Originally Posted by 78w72

youre using 1 3/4 headers right?

Yes Hooker Super Comps...

[Steve C.]

When they first came out the KRE d-port heads were reported to flow 226 at .500 lift on the exhaust right out of the box.

( High Performance Pontiac magazine / Feb 2004 )

As cast they had a 88 percent exhaust-to-intake flow ratio at .500" lift. With TA Man's intake port work and leaving the exhaust ports as is the ratio came down.



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[ta man]

Originally Posted by Steve C.

When they first came out the KRE d-port heads were reported flow 226 at .500 lift on the exhaust right out of the box.

( High Performance Pontiac magazine / Feb 2004 )

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That seems high..My 290 KRE SD's only flowed 203 cfm before at .500...I wonder when they stated 260/220 cfm in the magazine that was at .550....? Makes more sense? I never fully trust magazine articles..especially when they are pushing new products.

[Steve C.]

At .500" lift the magazine article reported 256 intake and 226 exhaust at 28". There has always been some controversy with the numbers.

calculating header design

http://garage.grumpysperformance.com...er-design.185/


And if you get a KRE product involved in the discussion be aware their flow bench is a Pitot Tube type. It does not correlate with a SuperFlow Edge Orifice type bench in any way. Thus for interest if you get looking at formulas they work on Edge Orifice Flow Benches.


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[Skip Fix]

Originally Posted by ta man

That seems high..My 290 KRE SD's only flowed 203 cfm before at .500...I wonder when they stated 260/220 cfm in the magazine that was at .550....? Makes more sense? I never fully trust magazine articles..especially when they are pushing new products.

Along those lines year ago Muscle Car Review had an article on a 455 SD my old machinist built. He had a very conservative dyno but cars "ran the numbers". Used an UD cam. Well the dyno numbers were too low it was taken to another shop for dynoing again(on the east coast so not Westech) and since Comp advertized in the magazine it became a Comp cam and not a Ultradyne.

Lots of articles about motors dynoed at Westech taken to the track that do not run the numbers.


I think Roger Bolinger in Germany has the Tribal tubes on his Butler road race motor.

I can tell you my Hedman step 1 3/4-1 7/8 lost HP on a friend's 462 roller motor SD Perf ported E heads that made 640 HP and runs mid 10s compared t the 2" headers.

I plan on dynoing my 0.060 455 ported round port E heads Stump Puller cam motor with the Tribals, my step Hedman's, and my Hooker 2" this spring. So more info then. Just got an associate so I might can have a day off for dynoing it now! Last year just me and working my butt off.