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Re: How Good is Maniflow Intake Manifold ?

To: "Steven P. Clifton" <>, mgs <>
Subject: Re: How Good is Maniflow Intake Manifold ?
From: Bullwinkle <>
Date: Mon, 03 Sep 2001 12:10:28 -0600

They say
Unfortunately the huge cross-over the factory  put in causes a
 disruption to the flow that is trying to get into the port.
Not so, there is a plug inside with a small hole in it about
5/16" I believe.  The bolt in the middle of the manifold holds it
in place.

They say
This flow disruption is so bad, that the high speed air which is
normally at the
 top of the port in the head is now at the bottom. This causes
 turbulence and flow reduction when it gets towards the valve
seat. The
 reason being that the short side turn into the cylinder requires
the air speed
 to be slower to make this abrupt turn with any reasonable
success, and the
 long side more gentle turn (spark plug side) can accommodate
 speed air.
Tuburlance is not always bad as it increases the atmozation of
the fuel.  This makes the fuel distribution more even.

MG has made intake manifolds straight in.  They are angled on
many cars to help get the carbs foat chambers away for the
EXHAUST manifolds and the heat.  It also provides more space for
the exhaust manifolds.

A straight intake manifold could be used, however there may be
clearance problems with the carbs or their filters.  The MGA is
one.  Note how MG had to dimple the inner fender panel of the
MGA.  The TF used 1 1/2" carbs like the MGA.  However the bodies
were shorter to clear the side panels.  But MG went back to
longer bodies because they had more room.  And the further the
carbs are from the head the greater the lever arm for vibration. 
That can upset the mixture which causes problems with the twin
cam.  Everything is a compromise.

Their claim of 4-5 BHP is probably at the top end RPM.  This gain
decreases to probably not more that 2-3 BHP at the RPM most
people use their engine at.  That's not much for the street car
and the cost.


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