Leyland P76 Owners 2005

Technical Information

Header design

from the 215V8@yahoogroups.com


Question

To: 215V8@yahoogroups.com
From: "frederic"
Date: Thu, 8 May 2003 09:49:15 -0400 (EDT)
Subject: Re: [215V8] header design
Is there any formula or guidelines in chosing the primary tube length for headers?
The engine is a 4.0 Rover with a fairly healthy cam and single plane manifold in a 1000 lb open wheel road race car. Building 4-1 headers with 1 1/2" primaries. Operating range expected to be 3500-6500.
Thanks

Reply

web2.iadfw.net/mkenslow/Calculators.htm
here is a better one:
www.slowgt.com/Calc2.htm#Header
Hope the links help you out, they've helped me in the past.
To: 215V8@yahoogroups.com
From: "Dave Williams"
Date: Thu, 08 May 2003 06:35:47 -0600
Subject: Re: [215V8] header design
v8mazda7 wrote:
Is there any formula or guidelines in chosing the primary tube length for headers?
There are lots of formulas, some of which give very different recommendations for header tube length and diameter. Most of the headers work pretty much the same in the end, though. The interaction
between the headers and carburetor seems to be more important than the actual header layout.
Pick some workable tube size where you can still get to the manifold bolts and have room to route everything, then route the tubes down to the collectors. For an all-out, single-RPM oval track engine you'd want all the tubes to be the same length; in practice, a 25% variation in
length just flattens the power peak a bit.
Almost all production headers have collectors that are far too small. For a 215, you'd want something on the order of 3" diameter by 18" long as an ideal size. Adding collector volume is good well past the point where you can't fit the collectors under the car any more, so don't
worry about going too big. Run your H-pipe or X-pipe immediately behind
the collectors. You can join collector-to-collector, through their sides, if it's easier to package.

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Feb, 2006
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