Working principle of the Flowtech Afterburner?

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Esky - 23 Dec 2003 05:54 GMT

Hi all,

ok, I know this is a controversial product that some say sucked big
time. I'm not here to start a war on whether it works or not, but just
wanna find out at least the theory of how it's supposed to work. From
its design, and even from the cut-away diagram, I simply can't figure
how it can be better than the 4-1 or 4-2-1 design... I'm always
interested in special designs and like to improve on it, if possible.
Well, improved in my head, at least! ;)

Oh yeah, is it only suitable for V8's? Coz there's no model available
for 4-cylinders on the Holley website.

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Esky - 30 Dec 2003 06:14 GMT

Anyone, please? Thanks!

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Ken - 04 Jan 2004 17:34 GMT

Well, from what I know, David Vizard, in one of his books, describes
how the V8 reacts to exhaust pulse tuning. The usual firing order for
early SBC's, for example, is 1-8-4-3-6-5-7-2; the odd cylinders are on
the drivers' side, the evens on the other. However, notice the 8-4
and the 5-7 in the firing order are two cylinders firing on the same
side, only 90 degrees apart, unlike the 6 & 2 cylinders, and the 1 & 3
cylinders, which fire 180 degrees apart. So, the drivers' side idles
at (1 3 5-7), the passenger side is (8-4 6 2). Vizard says that
because of this firing order scheme, the SBC acts like two inline "3
cylinder" engines, with one cylinder firing at a slower rate than the
other two. I looked over the Flowtechs once, after reading about
this. I don't remember, though, if that had anything to do with the
design.

Ken

> Hi all,
>
[quoted text clipped - 8 lines]
> Oh yeah, is it only suitable for V8's? Coz there's no model available
> for 4-cylinders on the Holley website.

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Esky - 20 Jan 2004 04:49 GMT

Thanks for the feedback. I found the following explanation from
jcwhitney.com, hope it helps with others who are also as curious as me
about the Afterburner:

//////////////////////////////

Big-tube headers offer plenty of horsepower but lack the low-end
torque twisting capabilities of small-tube systems or proven "tri-y"
designs. Afterburner? is a unique tubular exhaust that directs exhaust
gases of the out-of-sequence cylinder into a secondary collector.
There, the fumes are scavenged at a flow rate equal to that of the 3
other cylinders. Relieving the crowded condition in the primary
collector allows for a smaller tube design, resulting in increased
exhaust velocity (for added horsepower and torque) and a straighter
power and torque curve paralleling the engine's RPM range.

\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\

> Well, from what I know, David Vizard, in one of his books, describes
> how the V8 reacts to exhaust pulse tuning. The usual firing order for
[quoted text clipped - 11 lines]
>
> Ken

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