I've got a line on picking up a full 3" manifold-back Dynomax exhaust system for a REALLY cheap price. Only one problem. It is for a 1990 F250 7.3L Turbo, and my truck is an 86 F250 6.9 NON-turbo.

From looking at the pictures of it, it looks like the DS downpipe and crossover will probably fit as is. However, the PS downpipe doesn't look long enough and might not have the right kind of flange on it - I'm thinking that due to the turbo being on that side. That's not a deal-breaker since I can fab (or have any muffler shop fab) an extension for it.

My question is, will the rest of the system be the same? If not, it should at least be the same from the Y-pipe back, right? Even if I have to fab everything from the Y forward it is still a good deal. Just wondering if the manifold flanges for the downpipes (or at least the DS downpipe) will be the same.

 

If you are thinking that 7.3 is a powerstroke, you will be happy to hear it is actually the exact same thing as your 6.9 with some internal changes, up to 1994 will work, the powerstrokes came in at 1994.5. Basically, the manifolds, turbo and exhaust will trade, no issue.

 

No, I knew it wasn't a powerstroke, but I didn't know if both the manifolds were different, or if only 1 (passenger side?) was different, or what.

From what you're saying it sounds like the one side will bolt right up, but I'll have to do some fab work for the other side, and the rest of it should go right in. TOO COOL! I'm going to go for it.

Truth is, it is cheap enough that even if it only worked from the y-pipe back it would still be MORE than worth the price

 

What kind of turbo kit was it on? It probably won't have anything to bolt to the manifolds, they go to the turbo. The exhaust just hooks up to the turbo to head out the back. You can make your own exhaust with straight pipe and a few bends.

 

OK, sp what exactly are you trying to do? If you are hooking this exhaust up to a NA y-pipe, then you will want to rework the y a bit, and hook that exhaust right to that, similar to what I did on my 86. I built the whole thing, but if you can get ahold of a turbo exhaust from a IDI motor, or powerstroke to 97, you can make it work that way. You want to at least meet it at the junction of the y-pipe, and I personally would recommend reworking the y for better flow, which will make for a nice natural meeting point with that turbo exhaust. I have an article on the home page, click the articles, then go to the diesel section and you will find the step by step run down on how I did mine.

 

Here 's a picture of what I'm getting for $60


The kit includes a straight through muffler, pre-bent tail pipe, and enough pipe to go all the way forward to the Y-pipe. Even if the parts forward of the Y don't fit and I have to fab that part myself - then just the stuff from the Y-pipe back is worth that price - don't you think?

If I can use any or all of the stuff forward of the Y-pipe, well, that will just be icing on the cake.....

 

I would say it was worth it. You likely will have to make it fit to the Y though, but saves you a lot of the headache I had in fitting mine. You'll definitely be happy with it when you're done. I'm still quite happy with mine since I changed that out. Unfortunately, I misunderstood you were hooking it up to a NA, so no, it won't quite make it to the manifold, but I highly recommend rerouting the right side pipe to flow straighter back, which will meet about the same place the pipe would have come down from the turbo. Both manifolds would dump into the turbo, then the down pipe comes from the turbo out the back. The driver side pipe actually passeed under and into the passenger side to the turbo, then out to the back.Article here

 

Yup, read your article a couple of weeks ago fellro86 - right after I joined. Gave me some (I think) good ideas. I even downloaded the picture of the original Y-pipe from your article and kind of "doctored" it to come up with a couple of pictures of how I want to do mine. Here's the edited "mock-up" photos of what I have in mind


I'm thinking of installing the 45* piece in the same place you did, and patching the hole in the existing collector the same way you did. However, I think I'd like to cut the DS pipe off a little further back - right after it does its two 90* bends to run up over the crossmember. By bringing the PS pipe in beside the DS pipe (between it and the frame) on the same level as the DS pipe, I can fab & install a collector to make them both flow REALLY smoothly into the one pipe. If there isn't room for the PS pipe between the DS pipe and the frame, it might work better to route the PS pipe to the inside like this instead.....



See any potential problems or drawbacks to that idea?

 

Check out my gallery under the 86, and you'll see that it does shoot straight back over the crossmember, and I angled the cut internally so that it flows straight into the 3" tube. Nothing wrong with your ideas, when you get to fitting it, you'll find that happy place with it... you'redefinitely on the right track though.

 

Looked at your gallery. Yours is 4x4 whereas mine is 4x2 so that may make some difference in the crossmember and the amount of room I have for the pipe to pass through, but this picture
definitely makes me think that having the PS pipe on the INSIDE of the DS pipe is going to be the better plan. Not much room there between the pipe and frame....

 

Trying to remember, but I believe the 2wd cross is about the same for the most part, you're also seeing the skid too. One of my dad's 84's is also 2wd, as well as the 92, and I want to say over all it is about the same for room. Like I say though, you get to crawling under it and doing the fitup and you'll get a feel for what will work best for your truck. A reminder though, try to make your union about the cross or just before, I forgot that and had to take the cross down to get my pipe back up after I had it all welded...

 

Yeah, I picked up on that when I was reading your article

 

just wanted to be sure you learned from my mistakes... heaven knows my kids don't...

 

Well, I just picked it up on my way home! Pretty cool.

You were right. There is one pipe that obviously goes from the DS manifold, across under the engine, and up to the other side. The good news is that it is flared the same and has the same flanges and collars on both ends of that piece, so I should be able to cut it in two and use the two pieces as my downpipes. I'll just have to add some more pipe to them to bring them together

It is all mandrel-bent tubing, so it should help reduce the restrictions a lot. Unfortunately, there is no Y-pipe at all - or even anything resembling a Y-pipe. Gonna have to fab that part entirely. Oh well, it was still a deal I couldn't pass up for 60 bucks!

 

This is the rear of the turbo setup.
The pipe you are cutting to get the connectors hooks to the drivers side manifold and the passenger side Y flange to get the exhaust up to the turbo.

You can also see the turbo outlet where all the exhaust goes into the downpipe on the turbo setup.