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Differences in Turbo Exaust Manifolds


kcambron

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I recall seeing pictures of two US spec manifolds side by side that were different. Been a long time ago, but it seems like 240hoke posted the picture. Dont hold me to it, though.

 

Edit: I believe the difference was one had the turbo flange more towards the middle of the manifold than the other.

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I've seen at least three different numbers cast into stock turbo exhaust manifolds; KN3, KN7 and WN4. The three piece European manifold I've seen reference to was listed as a KN2. I don't know what the number is for the turbo manifold from the L20ET.

Whether there were any changes between different numbered U.S. spec manifolds I also don't know. I'll have one in my possession soon (and bore gauges) if you need any measurements to make comparisons.

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One of the reasons for this question was to get more room for a 3" downpipe made with two 45's instead of two 90's. It also seems that if the outlet is located more towards the center of the manifold there should be more velocity directed to the turbo?

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One of the reasons for this question was to get more room for a 3" downpipe made with two 45's instead of two 90's. It also seems that if the outlet is located more towards the center of the manifold there should be more velocity directed to the turbo?

 

Maybe it to help with oil drainage with sumps with the pan at the front, ie early Skyline,

I think I may have issues with drainage with my US spec turbo manifold and front sump on my car.

see pic

100_7523-800_thumb.jpg

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From pictures, the US spec manifolds all look exactly the same on the outside.

 

Updated list US manifolds I've seen pictures of: KN2, KN3, KN4, KN7 and what looks to be KN11. I was mistaken about the WN4, there is no such thing. I had misidentified a KN4.

 

I just received my KN2 last week and here are some particulars in case anyone feels like making comparisons:

 

Bare manifold weight = 17.1 lbs

 

turbomanimeasure.jpg

 

A = 25.8mm diagonally between bumps

B = 23.1mm between bumps

C = 38.5mm top to bottom

 

Turbo flange inner diameter = 43.6mm x 57.2mm

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Just so my measurements don't get too confusing, I did use my cheapie Chinese telescoping bore gauges to take my measurements.

turbomanisnap.jpgturbomanisnap.jpg

That'll account for some minor variation. Even still, just measuring w/ calipers my turbo flange was 43.1 x 56.9 making Noodle's turbo flange quite a bit larger.

 

I also just tabulated the averages for overall port height and width right where the flange meets the cylinder head.

Average Height: 38.3mm

Average Width outer 4 ports: 37.5mm

Average Width inner 2 ports: 39.1mm

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There are two. I sent one to Calgary 280ZT and it was, of course, the 'wrong' one compared to what he had and had already exhaust plumbed the car for!

The L20ET manifold I had was exactly the same outwardly as the 81 I took apart.

 

But there is a 'forward' and 'rearward' location of the turbo---there are photos posted somewhere, that is true.

 

And there is the Euro Manifold, which has 1 5/8" runners and a hole for the turbo that doesn't have a big bump restricting flow to the scroll.

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  • 2 weeks later...

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