We have stepped primary headers but, no tapered primary headers..
Thread Starter
TECH Veteran
iTrader: (12)
Joined: Dec 2004
Posts: 4,354
Likes: 0
From: Rockville, MD
We have stepped primary headers but, no tapered primary headers.. I know that stepped headers are a proven way to make more power but couldnt one remove that step and use a tapered primary(think the rule of thumb sheet metal intake runner tapers)? a gentle taper that, in design, would go from the original size to the larger size in a specific distance from the head based on the specific engine. a taper that only became the larger size at the collector i would think wouldnt work nearly as well.
given a 1 3/4 primary at the head and a 1 7/8 at the collector would a tapered primary work more efficiently than a hard step? or is there low pressure area created by the step that helps scavenging? on the other hand.. would a tapered runner possibly create a veturi effect on the exhaust? just seems like something thats never really been explored or at least, not that i know of.
the obvious difficulty of mandrel bending a tapered runner would increase cost... but would it be worrth it?
given a 1 3/4 primary at the head and a 1 7/8 at the collector would a tapered primary work more efficiently than a hard step? or is there low pressure area created by the step that helps scavenging? on the other hand.. would a tapered runner possibly create a veturi effect on the exhaust? just seems like something thats never really been explored or at least, not that i know of.
the obvious difficulty of mandrel bending a tapered runner would increase cost... but would it be worrth it?
TECH Addict
Joined: Aug 2004
Posts: 2,866
Likes: 4
I believe the step is to stop exhaust waves douncing back and effecting scavenge of the cylinfers as the RPMs change. basically the exhaust gas pulses are reflected at either changes in presure or when they hit something. So the pulse is reflected back as the air hit the collector. Now if you where to run an engine at a specific RPM range (a narrow one at that) then you could tune this so the pulses actually help scavenge the air from the cylinders. However automotive engine generally ahve to operate at varying rpms and loads. If you where doing it properly then you would want a constantly varying length primery to allways have the exaust pulses giving really good scavaging of the cylinders. unfortunately that would be VERy hard to do and as soon as you changed something, ie the heads, it would throw it all out.
Same can be done for the intakes but is easier to do.
Thats what i have been lead to believe, could be wrong.
Same can be done for the intakes but is easier to do.
Thats what i have been lead to believe, could be wrong.
Thread Starter
TECH Veteran
iTrader: (12)
Joined: Dec 2004
Posts: 4,354
Likes: 0
From: Rockville, MD
wouldnt a taper act as a megaphone in that respect? not so much bouncing but giving the waves a way to expand and travel down the exhaust line?
DC- i know that hotrodders and bikes have used tapered, trumpet like, exhausts but im curious if the header primaries themselves could eliminate the step and use a specific taper to do the same task. if were talking about the primaries on the bikes' headers, my mistake.
DC- i know that hotrodders and bikes have used tapered, trumpet like, exhausts but im curious if the header primaries themselves could eliminate the step and use a specific taper to do the same task. if were talking about the primaries on the bikes' headers, my mistake.
There is certainly a power gain to be had, but try to fit tapered pipes under an f-body hood. That's why no one has done it. That, and cost to fabricate. Tapered pipe isn't made by the ton like round pipe.
and i think that it would be way to expensive to justify the gains.
