🚀 go-pugleaf

Chuck Tomlinson wrote in message <7am212$f0g@sjx-ixn9.ix.netcom.com>...

>By the time you put baffles and ducting in to keep water from
>ramming itself into your engine along with the air, I don't think a
>ram air system provides any significant pressure increase at all.
>IMHO, calling ram air "forced induction" is wishful thinking.

>What ram air does well is providing a supply of *cool* air, where
>the factory ducting may not.  Any performance benefit from ram air
>systems comes from lowering air temperature, not raising pressure.

>Cool air is even more important to blown engines than it is to NA
>engines, so I agree that ram air (oops, cool air) systems can help a
>forced-induction engine.
>--
>Chuck Tomlinson

I agree that ram-air systems aren't too terribly useful at legal road speeds
in the 55-65 range, however forced induction does not necessarily have to
mean pressurization.  Ram-air also takes advantage of the mass and inertia
of air to minimize a drop in intake plenum pressure.  A mere pressure drop
of 0.5 psi at wide open throttle (a real possibility depending on the motor
and ducting restrictions) could mean as much as a 3.4% deficit in power.  On
a motor capable of 200 HP, this works out to 6-7 HP, a significant
difference.  Merely maintaining the pressure in the intake to atmospheric
would be worth the effort IMO.

A friend of mine has run A/B tests on his Storm with ram-air type ducting
and without - all using the original airbox and plenums - and he was able to
find several tenths quicker 1/4 miles times out of it.  Being that all of
the original ducting restrictions were still in place, I have trouble
believing that there isn't any pressurization, and the location of the
original pickup doesn't lend much to picking up hot engine air in the fender
given the way that it is isolated from the engine compartment.  Granted, the
scientific controls in this experiment may be somewhat suspect, but he
managed to get faster times out of a longer, less direct intake plenum at th
e track.

Take a look at modern motorcycles as well.  They hardly have a problem with
getting cool air, yet sport bike makers have gone out of their way to put
ram-air ducts in the front of the fairings, despite the obvious downside of
collecting bugs or whatever else should happen to get up that high.

If you're still having trouble swallowing the idea that air is pressurized
in ram-air systems, stick your head out the window of your car at 100 MPH
with your mouth open.  I have a feeling you'll swallow that . . if not a bug
or two. ;-)

Unlike turbos, which some have been erroneous in calling free horsepower,
ram-air is free power so long as a person isn't creating more frontal area
or turbulence to take advantage of it's effects.


--
Kip C. Anderson
kca at rio dot com