Re: Re:Why the stock 4.7 air hat is special

From: Marty Galyean (mgalyean@acm.org)
Date: Wed Sep 20 2000 - 19:54:18 EDT


The PVC thing is purely a subjective choice. Cost vs. chance of it shattering
kind of thing. I could see going either way. The po-boys are a great alternative
for cost and lack of heat transfer etc. I just wanted to point out a factor in
the decision process.

With all the latest input I'm beginning to agree with the posted concept (Steve
StLaurent?) that the chamber in the hat is de-tuned for less noise and not tuned
for more low end power. I think they are kind of opposing goals as resonance
would definately cause more sound. If the chamber is set up to lessen the noise
then it probably lowers ram effect. But that doesn't mean that some kind of bose
chamber couldn't be used to lower the resonance of an intake or that a variable
resonance mechanism wouldn't be cool.

I would think that you guys with tube intakes should be able to notice when your
rpm is right to resonate your intake, I think it would be louder with a definite
pitch to it, and power would either rise or dip a bit when riding that rpm. It
could dip if the standing waves leave a valley in pressure at the intake valves.
It should rise if its a peak at the valves. Not sure how that wave phase could be
dialed in.

I think I'd like to fab up a couple of PVC ones for testing that are basically the
same shape but one is as long as I can fit under the hood and the other is a
shorty. Then compare felt low/high end power, listen for resonance etc. Then
when I find what I like, create one in metal. Maybe play around with variable
tuning on top of that.

Tim J Koth wrote:

> Well, but when I first put it on it does seem to have a bit of a loss although
> slight. In fact for the first day or so on my initial install was kinda
> disappointed in the performance. But then it seemed to really start waking up,
> to the point where it was nothing for that little 4.7 to smoke both rear meats
> and they're 31x10.5 15's in a 4x4 Club Cab. It sure impresses me! But now
> after having it off for a while and then going back to it the same thing is
> occurring. Maybe its my imagination, I don't know. But the loss of power both
> low and high end was very distinct when I went from the po-boy back to the
> stock air intake. And who can argue with my observations when I use
> scientific terms such as "wazoo loads" etc. ;-) Oh and Marty, your comment
> about the PVC and possibly having it grenade in an accident sure got me to
> wondering. I am looking to eventually replace the PVC portion of mine with
> metal, but I went this route simply because I'm a po-boy!!! If I do it in
> little stages I don't get any flack from the finance manager if ya know what I
> mean.... since I have the K&N cylindrical filter already now I'm hoping I can
> pick up just a metal tube or have one fabbed up for not alot of cash sometime
> soon.
>



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