Info needed on porting details for a stock Tuned Port Intake manifold

[James Boughton]

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I have seen intake mismatches around 0.020" (the wrong way) that have =
not showed any improvement on the dyno when improved.  As a matter of =
fact I've seen much, much worse.  I don't know much about anti-reversion =
(other than I don't like it), but a great deal of effort goes into =
achieving wave formation in intake and exhaust systems that will assist =
flow during the overlap period.  Maybe it's a combination of wave =
pulsations and flow and the only reason the intake systems I've dealt =
with did not see much difference due to port mismatch was due to the =
significant amount of wave activity.
	Anyhow, I only responded because I think (for what it's worth) that you =
probably don't need to worry too much about the interface lining up =
perfectly.  I would get as close as I could and not worry about it too =
much more.  If you can find a flow bench that would show a difference =
between 0.010" mismatch and a near perfect match I would be very =
impressed.

Jim Boughton
boughton at bignet.net

----------
From: 	Tom Cloud[SMTP:cloud at peaches.ph.utexas.edu]
Sent: 	Monday, June 30, 1997 5:21 PM
To: 	diy_efi at coulomb.eng.ohio-state.edu
Subject: 	Re: Info needed on porting details for a stock Tuned Port =
Intake manifold


>> >I have one small piece of advice, Gasket matching head is OK, but
>> gasket
>> >matching the intake manifold is risky.
>>
>> >If you gasket match the head AND the intake manifold, there is no
>> >guarantee that they will match up perfectly when bolted together.
>> There
>> >will always be some play when mounting the manifold (and the gasket)
>> on
>> >the head, and if there is even the smallest area where the incoming
>> air
>> >hits an even slightly protruding edge of the manifold gasket or =
head,
>>
>> >then all your porting work will be undone.
>
>> How about dowelling the manifold and head and then doing the flow
>> work?
>> You are then guaranteed alignment unless you screw up the dowels

how can you dowel something that mates on an angle ??  If
the head is shaved or the gasket a little thicker or thinner
(either the head or the intake gasket) it's not going to meet
in the same place -- seems t'me you'd have to shave the intake
flange to assure a fit if tolerances were on the tight side and
then put in a compressible gasket to fill any gap if they were
on the loose side

just my $.02 .... watta I know ?

Tom Cloud <cloud at peaches.ph.utexas.edu>


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