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Old 11-21-2014, 03:35 AM   #1
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Best OE intake system for a built 3.4/3.6 M96

I'm going ahead with this rebuild and will be doing a few mods to it along the way. ( 3.4 or 6 in my 986). I already have the 3.4 and all ancillaries.....and have picked up a 987 air box and larger MAF housing.

So from there is there any gains to be had. ?

Am I best off sticking with the 3.4 intakes.? I've priced up the x50 manifolds....the ally inlets aren't too pricey but the plastic plenums aren't cheap! Should I flow my OE 3.4 parts a little....I'm guessing that's all the x50 parts are..

Or would a 987 inlet be better

And finally the throttle....stick with 3.4 size or go to gt 3 size

I'm looking for rroad driveability and grunt....Not necessarily out. and out power at max revs!

It will run a freer flowing exhaust system too.

Runab

Thanks in advance
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Old 11-21-2014, 08:08 AM   #2
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The 2002> 3.6 heads flow better & naturally more displacement = more power especially at low rpms. What year is your Porsche? Are you subjected to emissions testing?
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Old 11-21-2014, 12:52 PM   #3
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I needed you two weeks ago.

JimK04....where were you two weeks ago when I was going through this same debate.

Not sure this is the best answer but it has worked great for me....BUT...a big learning curve!

Here is what I used:

Stock 996 3.4 throttle body, 987 intake air box with the back removed so it would fit in my 1998 Boxster. BMW MAF "holder" with a stock 3.4 996 MAF used in the BMW holder. REALLY TIGHT FIT FOR IT ALL. I used a ROW re-flash for my DME because I
did not have smog testing issue in South Carolina. I also removed my secondary air pump and system. Car runs really strong! Had other issues...if you are interested... let me know.
What was the price and source for the X-50 intake you mentioned? I used the stock 996 intake and therefore had to drop the motor and trans to compensate. Also,if you have a "direct cable" throttle it will also cause some issues.
Thanks, Reebuck1
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Old 11-21-2014, 01:23 PM   #4
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Thanks guys.

I'm in the UK so no smog test.

Will be running a custom dme tune.

Engine will be base 3.4 heads with possible displacement hike to 3.6.

The x50 parts...I got the numbers off PET and ran them by my main dealer....all available and in stock. The x50 also ran different intake cams....but they're like 600gbp plus tax.

Only the intake differs on x50 iirc....exhaust side all the same.
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Old 11-21-2014, 01:24 PM   #5
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And sorry...my car is 02 3.2.
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Old 11-21-2014, 01:51 PM   #6
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Quote:
Originally Posted by Reebuck1 View Post
JimK04....where were you two weeks ago when I was going through this same debate.

Not sure this is the best answer but it has worked great for me....BUT...a big learning curve!

Here is what I used:

Stock 996 3.4 throttle body, 987 intake air box with the back removed so it would fit in my 1998 Boxster. BMW MAF "holder" with a stock 3.4 996 MAF used in the BMW holder. REALLY TIGHT FIT FOR IT ALL. I used a ROW re-flash for my DME because I
did not have smog testing issue in South Carolina. I also removed my secondary air pump and system. Car runs really strong! Had other issues...if you are interested... let me know.
What was the price and source for the X-50 intake you mentioned? I used the stock 996 intake and therefore had to drop the motor and trans to compensate. Also,if you have a "direct cable" throttle it will also cause some issues.
Thanks, Reebuck1

just FYI
with ROW and SAI delete car will pass smog testing with flying colors.

you dont have to drop the engine, thats very poor solution.
just use engine cover from cayman. it is taller in the middle.

ask me how I know that......
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Old 11-21-2014, 01:51 PM   #7
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airbox - 987 is the ticket.
maf holder - depends on the tune you are running. 99x - use a cayman maf holder. 986 - saw the old one off your current air box and adapt it to your new airbox. I had a bmw maf holder in my hands and measured it; it looked to be a mm or two off the oem unit. 2 mm is over 5% difference; your ltft can only manage a 20% cumulative change in closed loop, and trims don't even apply when running open loop which might result in running leaner under load (not necessarily a bad thing for power and fuel efficiency, but perhaps stick with the higher octane fuels).
plenum - 99x. I have not held them side by side but 997 looks to have slightly better design. regardless, either is an improvement over 986. 987 has a flapper valve in it and probably best avoided.
throttle body - cayman or 99x. gt3 is bigger, but *I think* just gets necked back down at the 99x plenum so no gain unless you go to an ipd plenum (gt3 plenum is part of the manifold and the manifold is designed for the metzger engine so can't be used in our application).
intake manifold - if you want to use a 996 intake manifold on 986 heads you'll have to tap a couple of holes and build brackets for a couple more. everything lines-up otherwise. x51 intake is a little lower than base 996 so might fit a 986 without lowering the engine. 987 engine cover should help also.

Last edited by The Radium King; 11-21-2014 at 02:16 PM. Reason: beat by golonaus, and to add more stuff.
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Old 11-21-2014, 02:12 PM   #8
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Quote:
Originally Posted by jimk04 View Post
Thanks guys.

I'm in the UK so no smog test.

Will be running a custom dme tune.

Engine will be base 3.4 heads with possible displacement hike to 3.6.

The x50 parts...I got the numbers off PET and ran them by my main dealer....all available and in stock. The x50 also ran different intake cams....but they're like 600gbp plus tax.

Only the intake differs on x50 iirc....exhaust side all the same.
Early 3.4 has thinnest M96 cylinder walls & most prone to irregular wear, so be sure to measure cylinders for wear, or just sleeve for 99mm bore & big boost in torque!
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Old 11-21-2014, 03:22 PM   #9
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In about six months ... when I get everything sorted out correctly, I intended to re-sleeve up to 3.6 which I believe LN can do without me needing a new crank or rods. One of the concerns is what size CAT by-pass pipe should I then be using? Is 2" to small or is 2.25" large enough?.. What does that do to my throttle intake size at that point? ...and will my 987 air filter then be too small? Any thoughts? Not sure if I am running too lean right now or not because I am running straight pipes and I am not comfortable with my Durametric readings yet.
Thanks for your feed back!
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Old 11-21-2014, 03:51 PM   #10
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99mm sleeves will give you 3.6L with stock crank & rod length. Keep in mind this takes about 6 weeks thru LN. Most oe style mufflers are 1"& 7/8" inlet with a few 2" aftermarket options. I believe 2" is fine for street use. DME will adjust fine either way you go.
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