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Old 03-30-2010, 07:48 AM   #1
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Default Lower Intake Manifold

Just happened to have an extra one from the 97 transplant. Got to playing with my Dremel last night. Took about 30 minutes or so to do one runner. Anyone else got ideas of what I can do to this thing experimental wise?





I did the same thing a few years ago on my 95. Polised and ported the LIM to match the cylinder heads. Opened up the airflow better. Did notice a difference in the butt dyno. Now that a few years has passed, I'm curious to know if anything else can be done with this thing. BTW Boosty, I didn't put this thing in my dishwasher.
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Old 03-30-2010, 08:06 AM   #2
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Good job on the runner. I would saw do your best to gasket match. Every little bit helps.
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Old 03-30-2010, 08:50 AM   #3
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I don't dishwasher either, that'* wretchedly disgusting. I eat off my dishes. I find a pressure washer gets them sparkly. Just like a machine shop, without the box around it.

What I'd do Mike is clean the outlets to reasonable rectangle shape, smooth the runners (like you did), open the coolant u turn under the TB, block the coolant ports to the UIM (bomb proofing the engine) and smile.

I disagree about gasket matching because the heads aren't gasket matched and the transition won't flow smoothly. Realisitically the gasket being larger than the opening causes some turbulance, but there'* really no benefit in my eyes if you don't open up the heads as well.
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Old 03-30-2010, 11:22 AM   #4
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That looks really good! I am thinking about going either N/A intake or F-Body intake for my turbo build.

Bill pretty much covered it, and gasket marching is really hard to do right, if you open up the intake too much they there will be a sharp edge in the direction of the air flow, its best to have the intake manifold slighly smaller than the head. if you looked at one side it would look something like this ----------______ Red would be the intake and blue would be the head an gasket.
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Old 03-30-2010, 12:04 PM   #5
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I was refering to the top inlets. The head inlet is .9 inches wide and 1.9 inches tall. so no larger then that.
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Old 03-30-2010, 01:58 PM   #6
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Right on the head size.. but one of my bigger pet peeves with an old admin here was that he said it didn't matter how you made the .9 x 1.9

It matters greatly. If you don't line up to the heads and say the gasket is skewed a little left or right because it has that ability to move slightly, you might create an issue just by bolting things down w/o sticking a finger in and aligning it. Us L67 guys can't see all ports like the L36'* can, and that'* something that I've always felt should see more attention.

When we recommend porting, we should stress that symmetry and measuring can be done to ensure things are in the right places and that a simple measurement of .9 x 1.9 isnt' what folks think is best. Placement matters.
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Old 03-30-2010, 06:06 PM   #7
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Bill, last time I did match both ports. Head and LIM to the gasket. Like you said, you have to feel for the placement of the LIM when matching. I think I had to take a picture of every port when it was on the heads. Just to make sure I had them lined up correctly when opening the ports.
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Old 03-30-2010, 10:00 PM   #8
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Smooth unobstructed flow, that'* all you need. A bore scope can be very handy in this case.
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Old 03-31-2010, 07:21 AM   #9
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Somewhere, I don't remember where though, I could have sworn someone saying something about coating the inside runners with clear coat. Not that I intend on doing it, but worth mentioning at least.

Bill, could you show me which ports you are referring to when closing them off.

Dan, a borescope would be nice to have, but when the LIM is sitting on the heads, I have a good view all the way to the valve stems almost.

Currently, this is how my engine is setup. It'* weird and sometimes I have to think about it.
Block is a 97. It didn't come with the current 97 car. Came from the mens mall a couple years ago. (after spinning a bearing for the second time)
Heads are original off my 95. Already ported and polished.
Accessories are original 95 except for 97 sensors etc.
LIM and UIM are original 95. LIM is already polished and ported to the 95 heads.
Just looking to see what I can do different this time around other than P&P.
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Old 03-31-2010, 08:08 AM   #10
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We may be saying the same thing Dan.. but I want to make sure we are clear for all the folks reading this.

if the ports on the LIM are opened up all on the left side only when you are porting, then the port has the potential to be pushed to one side. The head will be symmetrical and the LIM may not be. Especially on the L36 LIM where it is a mess when you first look at it. Following old gasket lines would give you a reasonably symmetrical pattern to follow. And still the gasket didn't necessarily line up perfectly at the factory.

What I'm suggesting is measuring and ensuring the ports are centered to the gasket and the heads for porting. This should ensure that upon reassembly you have the desired result.

It might start out looking like
o.....o.....o
and end up looking like
O....O.....O

Together
o.....o.....o
O....O.....O

See how the ports are enlarged and slightly skewed left or right. Say this is done by the porting and not just a poor excuse of a demonstration with o'* and dots. Too far to one side is a bad thing that will make the manifold non-symmetrical.
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