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Discussion Starter #1
Is there any reason the Intake Plate and Intake horn are shaped as angular as they are?

For the price of Buying the parts to get rid of my JWAC i am considering machining an intake myself. Im thinking a 3" pipe cut at a steep angle and welded to an intake flange. Ill draw a rough sketch and see what you guys think.
 

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The turbo diesel setup is entirely different from a gasser intake manifold. The gasser depends on manifold vacuum to draw in the air charge, at only 5-25 or so inches of mercury. That demands ultra smooth curves to enhance intake flow and reduce restrictions to ultra-minimum.

Toss that all out the window with forced induction. On the 4BT/6BT all you're doing is pressurizing a chamber in the cylinder head, how you do it doesn't much matter. Total pressure/volume is the real question, not gorgeous smooth curves in piping. Just get the air rammed in there through the largest practical piping from the correct turbo and you're good to go.

The apparent restriction in the 4BT intake area isn't quite what it appears to be. If you saw a cutaway cross section of the actual intake runner to a single cylinder, and realize the real world volume/pressure of the turbo-charged incoming air charge, you'd see that it's all far more than adequate for most normal or fairly hot requirements. The screwy right angle turns, sharp corners and square holes don't matter much on an engine that isn't all out race built.
 

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Discussion Starter #4
That sound like a fair analysis to me. Thanks!!! Ill save the mig wire for another project.
 

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By the way, don't feel like the Lone Ranger on that one! I just realized all this very recently during the very slow progress on installing an intercooler. I was downright shocked when I saw the square/rectangle openings, dinky little passages etc. on air horn & intake plate. Then some analysis revealed the rest, as seen in my post below.
 

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Don's Hot Rod Shop in Tucson, AZ has mandrel bent tubing.

http://donshotrodshop.net/CandyPress/Scripts/prodList.asp

Since my intercooler has 2.5 inch fittings, I picked up a 2.5 inch u-bend when I was in Tucson. I have not built an intake - But, the u-bend sure looks pretty sitting on the shelf.
 
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