Monday, January 16, 2012

Turbo exhaust fabrication

Now that the radiator and transmission are in place I can finally get started on what I think will be the most challenging part of the project - fabrication of the exhaust system for the turbocharger. There's not very much room for all the piping so things will have to be fitted just right.

My first step will be building a couple of exhaust manifolds. The stock 6.5L manifolds won't fit. I looked at the Humvee headers and thougth I could use them but nope, not a chance. So here I go making my own manifolds. First I had Metal Products Company ( my neighbors) laser cut some flange plates to bolt the manifold to the head.
Laser cut steel flanges. I had Metal Products make 20 of them so I would
have plenty to ruin while I figured out how to build the manifold.

I wanted to just make one long plate with the appropriate holes in it for the exhaust ports and bolt holes. Unfortunately, unlike other motors I've seen the exhaust side of the 6.5 head is not one machined flat surface. Instead, there is a separate machined surface around each exhaust port with raised raw casting in between. That means making separate flange plates for each port.

I found some 1-1/4" stainless steel weld up schedule 10 pipe elbows. These are just the right size to make the bends coming out of the port flanges. In the hydraulic press I mashed one end of the elbow into a rectangle shape to fit into the exhaust flange. Here it is tack welded in place.

One passenger side exhaust elbow
Once I had the size and shape figured out I made a tool to 'square' the ends of the elbows using the hydraulic press. 

The new manifold has to be very compact. Once all the elbows were formed, fitted and welded I made a fixture to cut them all off at the same angle in preparation for welding to a 'log'.
Four drivers side exhaust elbows

Transmission test fit

I finally found a 2nd generation 4L60E. It's longer than the TH350 that came out of the car so something had to be done with the tranny mount. On the Corvette the transmission mount bolts to a removable crossmember that spans across the frame rails. I considered modifying the stock crossmember but I found an aftermarket crossmember at Bow Tie Overdrives that bolted right up with no mods and has the benefit of increased clearance for the exhaust.
There's the 4L60E bolted right up to the 6.5

Bow Tie Overdrives crossmember.
It's intended for the LS1 motor swap but works perfectly here.
The trans is just temporarily bolted in place. I need it there to start working on fabricating the exhaust. I'll have to order up an appropriate torque converter, and probably modify the dipstick tube before it can be bolted in permanently. The Bow Tie crossmember will also need to go out for powdercoating. I ordered it in raw steel because I wasn't certain I would not have to make some modifications. Grinding off powdercoat to make welded modifications is a big pain.

Radiator & coolant hoses

I've been making good progress but it takes a while to get to the point of having something to show. The radiator is in. I ended up cutting off the bottom half of the stock radiator support and moving the radiator as far down and forward as possible. This will give me more room in front of the motor which is where the turbo has to live. With the radiator mostly out of the way running the turbo plumbing will be much simpler.
Here's a view of the radiator from underneath

View from the top. The radiator sits about a foot lower than original.

The coolant plumbing is made up of silicone elbows and aluminum tube. The straight pieces of tube need a lip formed on the end to help prevent the hose blowing off under pressure. I made a  quick & dirty tool to crimp the hose bead into the tube ends. Check it out.

The disk pushes tube lip into the 'V' groove.
Make a crimp, rotate the tube a little and repeat.