questions about a few mods, need advice

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dennhop

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Nov 10, 2008
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So a buddy of mine just swapped out his exhaust from his new 6.7, going from 4 in to 5. I don't know yet if he swapped out his dp too, but that's where my question is. The rest of the exhaust will be easy to do, if its just the dp back, to adapt it, but if the dp is there, what are the differences between the mounting flange on a 1st gen dp and the 6.7 dp? Would it be possible to make that work?

He also replaced his intake horn, with an aftermarket one, and I was kinda thinking that if it would fit, id try and swap those out also, but is it worth it? Is there enough of a difference in the inside diameter to make this work? I have little experience with the 1st gen 12vers, and none with the 6.7s, so any input would be great. Thanks!


Edit...sorry, I haven't changed my sig yet, but the truck I was planning on putting this on is a stock 93 12v.
 
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I dont think that it will mount up correctly, the stock 6.7 dp will stop short of where you need it, being the turbo is mounted in a different place.
 
Hit post too soon. With some nice new piping off a new truck and a welder and a cut off saw, you can probably make darn near anything work.
 
Yeah that's what I'm planning. I did just find out that its not a 6.7, its a late model 5.9, so I don't know wha if any difference that makes for the dp, but if nothing else, ill just tap the 4in into the bottom of my dp, and run a 4in dp back for now.
 
The downpipe probably won't work, but the rest of the exhaust should work, especially the tailpipe. I'd say just build a 4" downpipe out of 2 90* 4" elbows and a 4" piece in the middle, then weld the turbo flange off your stock downpipe and then ya got full 4", keep the 3rd gen dp though, you may want that turbo flange if you ever upgrade your turbo to an he351 or any other turbo with a 4" outlet.

As for the intake manifold, I think the 3rd gen ones will fit our trucks if its off a 5.9, but I know the 2nd gen 24 valve intake manifolds are the best upgrade from newer trucks, not sure if they are the same as the 3rd gen ones or less restrictive though, but i'm sure its better than your stock one.
 
the 351 has a 4.4" outlet on it. Plus unless you use the elbow with the 351 the flange does you no good for the turbo. Im almost sure you can't use the elbow thought on the 1st gen trucks cuz of the lack of room but I could be wrong.
Also I am confused about you saying he is going to a 6.7 exhaust that is 5" I take it that the 6.7 exhaust is not stock? Also if he already has a 4" exhaust on the truck it is not stock either so then why would he put a 6.7 exhaust on the truck?
 
This thread has me really confused. Maybe i am missing something but if Im not. Dennhop I wouldn't even try this with your truck. You can buy a new 4" turbo back exhaust for a 1 gen for $275 shipped.

also if the truck is 4x4 you are going to have a lot of trouble getting the 4" by the transfer case. One more reason to just buy the kit for a 1st gen
 
you can use the 4" flange off the downpipe and weld it to a 4" downpipe and v-band clamp it to the turbo and not use the 45* cast elbow. Thats how i did it and it worked fine
 
The fact that the flange on the dp is tapered and the flange on the turbo with the elbow off isn't doesn't matter?
 
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