NetNews Usenet Archive 1992 #16/NN_1992_16.iso/spool/rec/autos/tech/10148

Internet Message Format | 1992-07-25 | 1.7 KB

Path: sparky!uunet!cs.utexas.edu!swrinde!mips!mips!svcs1!twc
From: [e-mail] (Ted Chan)
Newsgroups: rec.autos.tech
Subject: Re: what are headers? and what's a turbo trans?
Message-ID: <[e-mail]>
Date: 25 Jul 92 23:55:03 GMT
References: <[e-mail]>
Organization: Silicon Valley Computer Society, Sunnyvale, CA
Lines: 23

From article <[e-mail]>, by [e-mail] (Peter Shyvers):
> In article <[e-mail]> [e-mail] (Steve Barnhouse) writes:
>>
>>I've seen people mention headers, and I'm currently looking at a Chevy
>>350 for sale that has headers.  What are they and what purpose do they
>>serve?
> Headers are exhaust pipes - often pipes quite literally, as most stock
> exhausts are iron castings - which are "tuned" by (a) increasing the diameter
> and (b) varying the length of the pipes. The former allows a freer flow of
> exhaust; the latter "times" the pulse from the exhaust strokes of the cylinders
> so that they don't conflict with one another. The goal is to reduce back
> pressure on the cylinder.

Actually, a well designed header does a bit better than that.  The exhaust
is emitted in pulses and if the header is tuned properly, the low pressure
behind the pressure peaks can be timed to "scavenge"  or suck the exhaust
gas from the other cylinders, which also has the effect of drawing a better
air/fuel charge through the intake side.  Good headers are well worth the
price, but tend to be noisier and more leakage prone than the stock manifold.
I think the sound is kinda cool, but that's definitely a subjective matter.
Legality may be a problem in some states...

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