[Shotimes] Interesting...porting the intake

[Don McKinnon (AST)]

Bruce,
A while ago (years ago?) there was talk on this list about why some engines
are strong and others are not.  My intake seemed to have less mismatch
compared to what others were talking about, stock it ran very strong 193TQ
and 195 HP.

Laminar flow is definitely the best.  I have an article on heads that states
the power losses of airflow can be up to 3% just based on the rough surfaces
in the head intake track alone.  Add in the rough intake runners and
mismatched alignments that number surely takes off.

Time for BBB and EH intake or hand ported intake!

Don McKinnon
95 MTX - White/Mocha 92k miles
Stage 1 Power Package with Stage 1cams
Canyon Carver Road/Race Suspension
Quaife & HiRevs Competition Clutch

-----Original Message-----
From: shotimes-admin@autox.team.net
[mailto:shotimes-admin@autox.team.net]On Behalf Of Bruce Malachuk
Sent: Tuesday, August 05, 2003 4:27 PM
To: SHOtimes
Subject: [Shotimes] Interesting...porting the intake


Well over the past few days I decided to put my dremel to the test and port
a
portion of my intake. Mainly enlarging the TB area for a 69mm TB, which I
got
for $40 and it turns out to be an 89 TB so it has a much lighter return
spring
than the 94 one that was on my car. So I ground out the opening and smoothed
it's transition, making sure to leave a slightly rough surface. Then I
decided
to look at the openings of the runners with my new felpro set. Well we all
know that there are gains to be had from gasket matching and whatnot, but
something I found that was not expected.

The mating surfaces of the tanks to the long runners are in particular very
very mismatched. If you take a dental mirror and look thru the front tank
when
the long runners attached you'll see a 1-2mm lip that is quite mismatched. I
have yet to finish, but I think this mismatch might be considerably more
important to the low end of the engine than even gasket matching the runner
to
head interface. I'm just guessing here but I'm thinking that the lip is
causing a 5% or so blockage to the long runners, and with that creating a
ton
of turbulence to the low end. I'm planning on gasket matching an intake
entirely other than the runner to head mating surface, and then leaving one
stock and trying to take them to a dyno day and swapping them. I think the
mating surface to the tanks on the long runners has a ton of potential
waiting
to be unleashed.

Wanted to see what others had come up with or seen.

Bruce
94 Opal Frost MTX
93 Black ATX - winter beater then parts car :-)
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