I totally agree with Jon. The engine is ONLY going to take in what it can.
If it's only going to take in 500CFM, a 1000CFM filter isn't going to help
at all (except cleaning intervals). You can increase velocity and
(slightly) volumn, but that's going to require tube size, stepping of the
actual diameter, and a lot of math to get it right. How much more...nothing
substantial.
Filter material, design, and thread density do matter though - you can get a
filter that's "capable" of handling 1000CFM, but if the material isn't
designed properly, it may only flow 700-800CFM. Still, that's more than
enough for a V6 (800CFM). The calculated max CFM for my V6 is 620CFM, but
I'll never rev it to 6500rpm so there's no use in grabbing something that's
going to flow much more than that. I do, however, have a 6"x10" filter on
the end...why, I'm lazy when it comes down to cleaning the filter. :)
- Bernd
-----Original Message-----
From: jon@dakota-truck.net [mailto:jon@dakota-truck.net]
Sent: Tuesday, July 31, 2007 11:13 PM
To: dakota-truck-moderator@bent.twistedbits.net
Subject: Re: DML: RE: K&N FIPK Heat Shield
Kyle Kozubal <solocamxt@sbcglobal.net> wrote:
> The RC-5040 filter flows 660.91 CFM, which is more
> than enough air flow for my 4.7L V8
> I have had great results when using a 900-1000 cfm
> filter on both the 3.9L V6 and the 5.9L V8 motors.
> I have a 68.50 MM TB on order and was looking to
> increease ait flow into the TB, to around 850-1000
> CFM.
> The K&N FIPK gets air flow from the duct coming out of
> the passenger side fender. The duct is rather small,
> restrictive, and mostly blocked by the PCM.
> I am going to install a larger filter and remove the
> heatshield, and see what happens.
You are of course welcome to spend your money as you wish :-) and
experimentation is what hot rodding is all about, so have at it!
I personally don't expect you to see a gain though. An air filter
isn't like a turbo or a blower where by going bigger you can force
more air through the engine; the motor requires a certain amount of
air, and unless you go to forced induction, the equipment outside of
the engine can't force it to take in more air than it wants. Once you
get to a point where the restriction is less than the engine's needs,
there are no more gains to be had. So, if your current air filter's
flow is adequate, a bigger one won't make more power (although it will
extend your cleaning interval since you can go longer before the dirt
build-up starts restricting the motor).
Assuming that you have access to some sort of equipment to measure
the results like a dyno, drag strip or even a G-tech, an experiment
you can do for free would be to take your current air filter and cover
half of it with saran wrap or something, basically keep restricting it
more and more until you notice a difference. If you can cover 1/4 or
less of your air filter and you notice a drop in power, then perhaps
it is indeed holding you back. You can also try removing it
completely (just for a brief time) and see if that makes a difference.
If removing the air filter completely doesn't increase your power,
then neither will adding a larger air filter. (If you do such a test,
don't forget to correct your power or times to standard environmental
conditions.)
--
-Jon-
.- Jon Steiger -- jon@dakota-truck.net or jon@jonsteiger.com -.
| '96 Kolb Firefly, '96 Suzuki Intruder, Miscellaneous Mopars |
`-------------------------------- http://www.jonsteiger.com --'
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