Cool, an automotive engineer or is that aerodynamics engineer. Great
write-up.
Ron
00 SLT QC 4X2 5.9 46RE 3.92 LSD
For modifications see my DML Profile
-----Original Message-----
From: owner-dakota-truck@buffnet.net
[mailto:owner-dakota-truck@buffnet.net]On Behalf Of Marty Galyean
Sent: Wednesday, October 04, 2000 4:20 PM
To: dakota-truck@buffnet.net
Subject: Re: DML: Cowl Induction Vs Ram Air Which Better/How?
'ram' has two meanings. Many logically refer to cramming air into a scoop
via
vehicle motion as 'ram air' as Bernd notes below. But the other meaning is
what
automotive engineers mean by it and it goes like this. Because of the
opening and
closing action of intake valves, the mass of air in the intake moves toward
the
intake valves in a slinky-like motion. The frequency of oscillation is
mostly
dependent upon the rate of valve cycling. Because air is an elastic medium,
that
is it can compress and rarify, at any given moment the air at the intake
valves
can vary quite a bit in density. If you could freeze a snapshot of the air
density in the air column in the intake from filter to valves, the pattern
of
dense/rarified air alternates like a sine-wave. By tuning the resonance
properly
on an intake the 'ram effect' is achieved when the opening intake valves
nearly
always see a dense wave front rather than a rarified valley. Many cars have
tuned
intake runners in the manifolds to help achieve this and several makers are
looking to get the entire intake, not just the manifold, into the act.
Can't
remember the numbers but I recall some measurements in the neighborhood of 4
to 5
psi difference in density in the air-slinky in some test intake/manifold
combos.
bernd@texas.net wrote:
> Considering that neither will give you any true "Ram Air", they both work
more
> as a Cold Air Induction system. (Ram Air won't happen unless you're
driving
> above 100+mph...and at a very small amount.)
>
> Cowl Induction collects cool air from the windshield/cowl area and the
"Ram
> Air" hoods just capture cold air from the vents facing forward on the hood
> line. One thing to remember is that if you're running a Intake Tube Kit
or the
> factory airbox, they're both pretty much useless and work only for looks.
>
> - Bernd
>
> > Can someone explain how Cowl Induction works and is it
> > better or equal to Ram Air.
> >
> > My understanding of the object of the Cowl Induction
> > and Ram Air is to cool the engin and get colder air
> > into the engin. Is this correct.
> >
> > It appears that they both cost about $400 is this
> > correct?
> >
> > Any recommendations would be appreciated.
> > Thanks
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