pressure=hp quattrorunner@lvcm.com

[Brett Dikeman]

At 10:04 PM -0800 2/15/02, Brandon Adams wrote:

>Tell me, am I wrong in assuming that if the intake manifold
>experiences 15psi in one MC engine that uses stock EM and Turbo, and
>another more modified MC engine also sees the same pressure at the
>intake ports, it's still 15 pounds going into the combustion
>chamber? After all, if the engines still have the same set up at
>that point, (combustion chamber) 15lbs is 15lbs. Am I right? I
>realize that a better turbo and larger more efficient manifolds and
>runners will net you more flow and thus more potential, but will one
>engine make more power than the other without internal mods? I need
>help understanding this if I am wrong. Thanks for the help.

Okay, here's hoping I get this all right(crossing fingers):

Basically, no matter what the pressure, pipes will always restrict
flow, particularly if they're goofy shaped or have a really rough
surface.  Smooth is usually good in pipes for flow(not for golf
balls; they're dimpled for a reason!)  The problem with a really nice
smooth intake manifold is you have less turbulence, so fuel mixing
might not be as spiffy.  Maybe moving the injectors back further
would correct this, but I suspect there's probably a good reason they
are right where they are(someone else can probably tell you exactly
why, I have no idea.)

You're right, gains are not as large in a turbo engine since you're
pushing air into the engine, not relying on the engine itself to suck
air through the whole intake system etc.  Pressure losses up to the
intake manifold(where boost is measured by the ECU) will only hurt
efficiency because you make the turbo work harder to get the same
pressure at the intake manifold; it'll be making extra pressure at
its outlet, and the more you compress air, the hotter it gets, etc.)
If you can find an IC that performs in other regards to the same
capacity or better than the stock unit, then that's one sure way to
go to make the turbo work less(thus charge air temp will be lower
going into the IC!  Woohoo!); this is basically the case with the
200q20v single-pass IC.  Just a WHOLE lot more plumbing to make it
all work  on the 20vt :-)

The caveat is that a turbo car isn't always force fed, and it takes
exhaust to make those turbos spin...when you snap open the throttle,
it's initially an NA engine, and it could probably be argued that the
better the engine does in those conditions, the faster it'll
transition to a forced induction motor.  More exhaust flow spins that
turbo up faster...and if you just so happen to be running a larger
turbo(so you can run higher boost more efficiently), then anything
that helps get it going faster is a Good Thing.  I guess what I'm
saying is that as long as you don't hurt the engine while it's under
boost, if you help it while it's -not-, that's also a Good Thing.

Is it worth ripping the thing apart?  From what I remember reading a
few weeks ago when this thread came up with Javad etc, the advice
seemed to be "hey, if you've got everything off already anyway,
certainly, get the DIY kit and match the gasket surfaces etc on the
intake side, remove casting burrs and other obvious imperfections
etc."  I think Javad had a disclaimer about how matching the gasket
surfaces to the ports on the exhaust side was rumored to be less of a
Great Idea.

Note that installing a custom IC is both expensive and a royal PITA
for most Average Joes...and it's difficult to pick "the right one."

Brandon, I'd try some searches on the archives, see if you can find
an old thread that goes over this subject...like I said, it was just
covered a few weeks ago in a nice big long thread.

Brett
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