List,Neil
But the dyno test results would apply only to the specific engines tested,
each with their own valve timing, lift, duration, etc., the port sizes and
shapes and the exhaust gas temperature, pressure, and density, engine RPM,
exhaust tube and step sizes.
Maybe some empirical "rule-of-thumb" could be developed from such dyno tests
but they wouldn't necessarily work the same way when applied to the wide
range of engine designs and operating conditions used by people on the list.
A lot of analytical/experimental papers could be found in engineering
archives concerning "tuning" of both intake and exhaust systems in attempts
to get the benefits of acoustic resonance ("springs in the pipes") and other
effects, but the results are usually very engine specific. Had a coworker
who did some of that stuff with two-stoke engines. As I remember the old
long tubed Mopar ram induction manifolds, they gave a slight torque
boost(using acoustic resonance) only over a narrow RPM range. Similarly, I
suspect it will always be possible to find specific cases where tuning the
exhaust by stepping the headers,with length and diameter changes, will be
beneficial at some RPM.
But until some genius develops an analytical math model that includes all
the design factors and operating conditions and can predict the benefits for
any engine, and the benefits are verified by a number of different dyno
tests, we're always going to have this controversy. Mother Nature can be a
Bitch but it sure is fun twiddleing with her!
Everybody has been busy picking on the Turk----how come we haven't heard
from Mayf lately?
Lance
----- Original Message -----
From: "Albaugh, Neil" <albaugh_neil@ti.com>
Subject: RE: Stepped Headers
> List;
>
> It seems to me that a series of dynamometer tests could settle this
> "stepped header" question once and for all.
>
> Regards, Neil Tucson, AZ
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