Modifying exhaust manifold

[woodwright]

I've been working on putting a 6.5TD in an older truck and am having a little clearance problem. With the way my firewall and frame are, I can't fit the turbo downpipe past the manifold on the passenger side. If I could shorten the manifold, I think I can make everything fit. Heres where I'm thinking of cutting it.
http://i447.photobucket.com/albums/qq197/woodwright1/manifold2.jpg
I can't really find much on welding manifolds. I have a tig welder, just not sure of the process. Any help would be appreciated.

[jamesm]

Your power supply is fine, but you won't use it in TIG mode. Well, sometimes it's nice to stick weld using the variable control of the gas pedal, but with argon turned off of course.

Go to your local welding store and get a pack of stick from them (blister pack, ~10, 1/8" rods, ~$20) of cast-iron weld rod. Follow the directions with respect to preheat (get a temperature crayon from them, or use your IR gun), peening, and post heat and/or slow cool (wrap it in a big hunk of fiberglass until tomorrow). It will work fine, especially since it's not "structural," and is just the downpipe, with no turbo or brake caliper hanging off of it. I've welded Audi (gas, 1800 EGT) turbo manifolds, hydraulic metal-shear cross heads, antique (otherwise-unobtainable) Mercedes manifolds, etc.

[DaveBr]

I would use a high nickle rod on that. We call it Ni rod here. No pre - heat or wrapping required. Bevel your connecting edges get it as clean as you can and run your fist pass. If its ugly grind it out and go again. Peen every pass. Beautiful finish and able to handle wild tempurature swings.

[Robyn]

DO NOT cut the manifold. Welding it will result in a mess.

Even a new manifold is a bitch to weld and have it hold due to the extreme temperature swings.

Route your downpipe outside the frame then back and under to connect to your exhaust system.

I have done this on a Friends K5 Blazer that had a stock late model 6.5 installed.

Its not quite as pretty as the factory install on the late trucks where it all runs past the firewall, but it works well.

Just use some large "Prebent" exhaust tubing and fabricate your setup.

Just cut off the falnge the bolts to the turbo and then build from there.

Once under the truck you can bring it back inside the frame and then on back with some 3-1/2 or 4 inch pipe.

Good luck
Missy

[woodwright]

What about swapping the manifolds around and running the crossover pipe in the front. I haven't checked to see if the turbo will work on the drivers side.

[Burning Oil]

I like your out of the box thinking. Heres another idea (might be a stupid one)
"If" you were to cut the manifold do you think a machine shop could cut some pipe treads on each of the ends you would be keeping? Then use a short pipe nipple to join them again. Maybe a 3"?

Leroy

[dieseldummy]

Cut it and weld it. Done it a buch if you have much experience welding you'll be fine. Like mentioned before use a good high nickle rod or if you're feeling spendy that high dollar cast rod.

[phantom309]

Make your own sheet metal manifold,.you'll need someone to waterjet you the manifold plates for the head side,.or cut up a 6.2 miltary N/A manifold that looks like a header,..then you can put the turbo where you want it,.

JM2C

Nick

[stezloco]

I agree with dieseldummy, ive welded a few exhaust manifolds in my time and only had 1 failure which was a water cooled manifold on an old fire pump engine, it was just too old and fatigued, cracks kept creeping/leaking water.fabbed a new one in the end only to have a piston come apart at a later date at full revs with it unattended, wasnt pretty, or salvageable. 52 year old pistons will do that..

manifolds are cast with a high nickel content which helps to control their expansion when hot, so as long as youre using the appropriate high nickel content rod you shouldnt go far wrong, you can always grind off the crow sh1t to make it pretty... :¬)