[Shotimes] Interesting...porting the intake

[Ron Porter]

Again, "in general" it's the same as opening up the intake pipes. Velocity
drops, and the power curve moves up the rpm band.

Also, this is one of the advantages of engines with two or three intake
valves. They can keep a larger flow, but velocity remains higher rather than
using one big pipe.

Ron Porter 

-----Original Message-----
From: shotimes-admin@autox.team.net [mailto:shotimes-admin@autox.team.net]
On Behalf Of Paul Nimz
Sent: Wednesday, August 06, 2003 1:55 AM
To: Mark Nunnally; `V6 SHOtimes
Subject: Re: [Shotimes] Interesting...porting the intake


How about 20-25% bigger valve area?  What would this do?

Paul Nimz
'97 TR
'93 EG mtx


----- Original Message ----- 
From: "Mark Nunnally" <manunnal@netheaven.com>
To: <shotimes@autox.team.net>
Sent: Tuesday, August 05, 2003 6:14 AM
Subject: Re: [Shotimes] Interesting...porting the intake


> The more I read, and talk to folks a lot smarter than me, and tinker with
> these things, it's more apparent in an n/a motor, the cams/intake runners
> are a paired team.  Basically the stock SHO runners are designed (through
> shape/size/length) to create the best resonance (ram air effect) where the
> stock cams want to make the most torque.  When you shorten the length of
the
> runner, or enlarge the ID, you are changing the resonance rpm tune on that
> runner.  You'd be moving it up higher in the rpm range.  I also think the
> shape of the runner is important as well.
>
> I think EH is probably the best (yeah it's $$$) method to "cleaning up"
the
> runners.  What I would be interested in is having somebody measure up some
> EH runners and figure up the math to determine what rpm resonance that
they
> are "tuned" for.  Then build a cam profile to suit.  And of course
> gasket/port match the runners to the heads.
>
> One of these days I'll get around to port matching the intake/head runners
> on the 3.2L (mine have a terrible mis-match, one of the worst I've ever
> seen).  I borrowed an EH intake once and lost significant low end torque
> (above 3k it would regain itself).  Never ran it at the track to see what
> top end gains might have been there, but it seemed to pull hard.
>
> Realize going much higher hp that what you can get out of a BOS 3.2L is
> probably going to be maxing out the stock injectors.  I'm getting 90% duty
> cycle on my stockers on my 3.2L now (at 216 FWHP).  If you are shooting
for
> 300 hp some 30 or 36 lb'ers probably would be needed.
>
> I think for open track work the stock cams/runners do pretty decent, as
they
> make a lot of torque over a broad range of rpm.  Personally I'd rather
build
> power through more cubes (3.4L anyone? <g>) and compression.  Ie, things
> that will pick up the whole torque curve, and not just from 6000 rpm on.
>
> I think if you EH'd a set of runners, had a cam profile built to match, on
a
> John H. type 3.4L stroker motor using about 10.75:1 (or 11:1) compression
> (running on 94 pump gas) with a little more injector, I think you could
make
> an honest 300 hp with a GOOD torque curve.  Hmm, sounds like what I want
to
> build for the track 89 :)
>
> mark
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