Results of stepped headers/merge collectors vs standard headers

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Mar 7, 2007 | 06:43 AM

#46

Denny McLain

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Posts: 752

From: Double Oak TX

Quote:

Originally Posted by assasinator

stepper are good for several torque peaks if they match your combo, but there is a reason hooker's best headers have no step. narrow rpm band while racing. kinda what he said above. road racers can benefit.

I'm going to be a devils advocate......do you have first hand dyno data to back up what you said? Everyone I talked to who promoted stepped headers could not provide dyno data. Only theory. So far my personal data says......no gains.

All eyes, ears n teeth if you can support what ya said.

Mar 7, 2007 | 06:50 AM

#47

Denny McLain

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From: Double Oak TX

Quote:

Originally Posted by Damon

The level of this discussion has gone well beyond my experience or understanding but I have a header question that might relate to this.....

I've seen the NASCAR guys concentrating on something I've heard referred to as a "merge collector", I think it is, where the COLLECTOR necks down just beyond where the 4 head pipes come together and then opens back up slowly on the far side. Looks suspiciously like a venturi to me.

Does that design have any merit for a typical street or street/strip motor or is that also in the realm of "black magic" like stepped headers? Do the two work hand in hand?

It's all a designed system, but the length, diameters and taper of the merge collector is "supposed" to help. The headers I sent back had a 3" merge collector tapered down to 2.5 and back up to 3. My opinion........"black magic" Always however looking objective empirical evidence that says I'm wrong.

Again, all eyes, ears n teeth if someone has facts.

Mar 7, 2007 | 10:10 PM

#48

LT4POWR

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Posts: 586

From: Oklahoma City, OK

I know it’s apples to oranges, but it shows some more “expert” advise recently given regarding headers. My buddy has a late model EFI 427ci (small block) Mustang. He recently decided to change from…an approx. 240/250 dur. 550/575 lift hydraulic roller cam, AFR 205 heads, and converted Victor Jr intake…to an approx. 250/250 dur. 600/600 lift solid roller cam, AFR 225 heads, and converted Super Vic intake. Ed Curtis helped him spec all the new parts and recommended he also change from his old standard Hooker 1.75" LTs to new Kooks 1.875" to 2” stepped headers with a merge collector.

I also read the LSx forums a lot, and get the impression that Lou’s 1.75" merge collector super duper LTs, and the larger stepped/merge collector Kooks (and other similar brands) are the ones indicated to produce the best results.

Call me crazy, but it sure seems like your motor (398ci, 7000 rpm, screamer) would benefit from the larger stepped/merge collector design…why it doesn’t I don’t know.

Mar 8, 2007 | 06:40 AM

#49

Denny McLain

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From: Double Oak TX

Quote:

Originally Posted by LT4POWR

Crazy with ya as I don't know either. Trust me, it was a huge dissapointment. and $$.

Oct 21, 2007 | 09:02 PM

#50

mdacton

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From: Goochland, Va.

Denny have you ever found out anything new with the headers or still running the same thing?

Feb 7, 2008 | 03:46 PM

#51

Steve in Seattle

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Joined: Feb 2000

Posts: 1,445

From: Seattle, WA

having just installed a 396 LT1 with a GM847 cam and big heads I'm also curious.

I went with AS&M mid-length headers (1.75" primaries), but I'm curious if there's more options out there that would retain ground clearance.