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JohnJL JohnJL is offline
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Join Date: Jan 2005
Location: Toronto, Ontario
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'Porting' the intake runners

What's the correct procedure for 'porting' the intake runners?

I've got my intake and exhaust ports about to be opened out to 38mm, and as discussed in a previous post I've noticed my intake runners are 33.5MM at the manifold. There is some material to open them out to 38, but I don't see how the rest of the runner can be similarly opened up with a dremel/other tool. There just isn't enough material further up the runners, even if I could reach it somehow.

An answer that occurs to me is to chop the runners off an inch above the injector bungs and use a dremel to open them up from the inside, then run a silicon hose with a 38mm ID from each chopped-runners to the airbox.

Does that sound feasible/like a good idea? What are people using for intake when they port out their heads?

this is a 3.0 on US heads, receiving JE 9.5CR pistons, megasquirt, DR20 cams.

It just doesn't seem right to creat a situation where, even if the difference is somewhat gradual, the air travels through a more constricted area (upper runner) into a more voluminous area (lower intake or port.) Seems to me the effect would be to slow down the air and create less pressure just where you want it most.

thanks all
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Old 08-07-2005, 01:02 AM
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