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Old 05-01-2007, 10:53 PM   #1
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Default How to port a front EM?

I've done some searches but most talk and show off their PEMS. I've gotten a set of "fake" PEMS and I would like to remedy the front one, I have my original that I can attempt it on.

I can't find specific L36 EM porting threads, how big do I make it, how much do I take off, etc etc.

If anyone knows, I would love to hear it.
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Old 05-01-2007, 10:55 PM   #2
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what do you mean by "fake" PEM
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Old 05-01-2007, 10:57 PM   #3
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i think he means that he has gotten an extra set of manifolds and wants to port them himself.
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Old 05-01-2007, 11:01 PM   #4
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fake PEMs means I brought PEMS that I thought was ported but instead the ends are just rounded (nowhere near a real porting job)
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Old 05-01-2007, 11:05 PM   #5
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You have to build up the material under the 'neck' of each runner with a welder. Since the front is cast iron, you need nickel rod. After building it up, you can port it to match what you do to the rear.
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Old 05-01-2007, 11:28 PM   #6
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is it good to port the maximun you can whitout welding . or its no use taking it off because i did see tj front and they are awfull .are they all as bad as this


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Old 05-01-2007, 11:38 PM   #7
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Quote:
Originally Posted by firebuick
is it good to port the maximun you can whitout welding.
I would make sure it'* welded otherwise the material could crack and cause a exhaust leak.

Ed
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Old 05-01-2007, 11:42 PM   #8
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i was thinking more to port the upper end than the lower you can see that the outline of the exhaust port is much smaller.i would only smooth the lower end
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Old 05-01-2007, 11:55 PM   #9
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Boy, that manifold looks pretty restrictive. Kinda glad that guy bought a powerlog Even without tuning it must do something
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Old 05-02-2007, 02:16 AM   #10
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I installed an...ahem..."fake" front PEM on my 98 LeSabre a few days ago. :P

"Fake" here meaning no added material and essentially what Firebuick said; I simply bought a stock front EM cheap off clubGP (that a guy had already begun to "fakely" port), drew a circle around the ports with a Sharpie (matching to a FELPRO exhaust gasket), then ground out the port to the circle with a dremel. I would say I just smoothed the short side radius (bottom), and took off a little on the insides at the top. Took maybe 30 minutes total, probably an hour if the first guy hadn't done half the "fake" work already.

I'm sorry I didn't get any pictures, but just imagine Firebuick'* pic above with the holes in the flange ground out to match the carbon rings.

If you can wait a few days, I will be qualifying this "fake" mod this weekend with the PowrTuner, and I can report what my "fake" front PEM did for volumetric efficiency, KR, and ability to advance spark.

(Butt dyno says "maybe", but nothing to write home about)

I did consider having a front PEM done at W-Body store, but the cost was prohibitive. Thus, my "fake" job.

I also considered a PowerLog, but couldn't justify $140 or so for something even zzp doesn't put a "fake" hp number on. Also, the kids at ClubGP seem to think their used, rusted out old PLog'* are worth their weight in gold.
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