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Old 10-28-2008, 01:02 PM   #1
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Default Porting LIM on L27

So I figured with all this talk of porting a LIM, I'll try it out on my own as well.

This thread is not so much asking for advice, as I can find plenty of it just by using the search feature on this forum, but rather to show people what I've done and how much of a difference it makes. I'll do some 0-60 runs on my Passport G-Timer before and after. While some may a G-Timer is inaccurate, mine so far has been accurate down to .02 seconds in the 1/4 mile, tested and verified when I took the regal to the drag strip last year.

For reference, here are the times i had:

http://i16.photobucket.com/albums/b3...eslips0001.jpg

What I've gathered so far is that the last thing you want is to over-port the LIM, as that would cause you to have a lip at the LIM-head transition, and would cause turbulence as a result. IIRC, I need to make my ports marginally smaller than 0.9x1.9, and can use the LIM gaskets as reference point for finding the center of the hole so I know what I can take off. I understand that the concept is basically to port them just marginally smaller than the head openings.

I plan on doing this with a dremel, as I really don't have any other tools. I've been given the impression that using a coarse drum sander would probably work best in this scenario, though i have a few more tools I can use if required, and a small budget for buying a few more dremel attachments.

The thing I do need some advise in is smoothing the runners. Is there much of a gain to this? Also, what would I use to do it?

Thanks for the help. I'll be posting pics of my progress.
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Old 10-28-2008, 01:06 PM   #2
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Just move slow, aluminum cuts easy. Polish all you can. This leaves less places for carbon to build up. As for what to get the inside with, How will I describe it? Think of a bunch of strips of sand paper connected to a post and it spins at the post. You'll know when you see it.
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Old 10-28-2008, 01:10 PM   #3
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Just move slow, aluminum cuts easy. Polish all you can. This leaves less places for carbon to build up. As for what to get the inside with, How will I describe it? Think of a bunch of strips of sand paper connected to a post and it spins at the post. You'll know when you see it.
You mean like a flapwheel? I have two of those, one a finer and one a coarser grit, and a very nice cordless drill as well.

Might I also add, since those track times, I've installed a CAI, 1.9 yella terra roller rockers.

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Old 10-28-2008, 01:16 PM   #4
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Perhaps it'* just me, but I really can't read them. Not very clear.
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Old 10-28-2008, 01:21 PM   #5
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Perhaps it'* just me, but I really can't read them. Not very clear.
Might need to zoom in. I can load them just fine.
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Old 10-28-2008, 01:26 PM   #6
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Yep, that worked. Greatlakes? As in Wisconsin? I'm just to the north of there. I had hopped to get down there this year but never made it. Guess we need to plan a meet some time next year. A little work and you can get in to the 15s
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Old 10-28-2008, 01:33 PM   #7
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Yep, that worked. Greatlakes? As in Wisconsin? I'm just to the north of there. I had hopped to get down there this year but never made it. Guess we need to plan a meet some time next year. A little work and you can get in to the 15s
I hope so. I've got a res delete and a magnaflow muffler on there. Stock cat though, but it doesn't seem to be bogging me down at all. Granted, I have 188,000 miles now.

The engine is running great and the tranny was rebuilt at 148k. Those runs were made at around 155k, and I seafoamed the car for the first time at 170k, which made a great improvement. Do you think this LIM port and polish will take me into the 15'*?

I haven't updated this in a while, but here'* a bit of what I have on the car now:

http://www.cardomain.com/ride/2935788/1

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Old 10-28-2008, 02:00 PM   #8
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Well, it will help a bit. But it needs to exhale as well. Some PEMs or a powerlog will help with that.
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Old 10-29-2008, 03:33 PM   #9
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Alright, I'm tearing up the engine tonight. Pictures to come as I make progress.

I'm hoping this will play very well with the roller rockers, CAI, and straight through 2.5" exhaust with the magnaflow muffler. The only thing restricting my airflow (and creating backpressure as I hear is needed to keep low end power) is the cat.

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Old 10-29-2008, 04:10 PM   #10
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What are you doing about your exhaust manifolds? If your staying stock then that is going to be your biggest restriction. And that will hurt your performance.
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