Transmission controller

 In spite of being a diesel this car still has to be fun to drive like a sports car. That's where the aftermarket transmission controller come in. I chose the "Quick 1" from US Shift as it looked to be the best value that still had all the features I wanted. This controller was also sold under the "Opti-Shift" name.

The controller came loaded with a diesel shift point program that was probably just fine for a pickup but needed a little adjusting for the Corvette. Making changes in the shift parameters is easy. You connect a laptop with a USB cable, pull up the program, make adjustment by moving points on the upshift and downshift lines based on throttle position and speed.

 

The Quick 1 will hold 2 different shift programs that can you can choose between with the flip of a toggle switch. It also can be put in manual mode and has inputs for paddle shifters.

It runs!!

I've connected wiring for the lift pump and injection pump solenoid. It starts and runs! Yay!!

Oiling for the turbo

I've been putting this off because I didn't have a good plan for getting the oil drain from the turbo back to the motor. I thought I was going to run the drain line into the unused crank position sensor hole in the timing cover. That wasn't going to work because there just isn't enough room work. I ended up running the oil drain straight back and welding an elbow into the oil pan.

It's a very tight fit. There's only a little more than 1/8" clearance for the power steering pump pulley and exhaust pipe going into the turbo. I'll add some kind of sheet metal heat shield between the oil drain and exhaust just to be on the safe side.

Getting oil to the turbo was a bit simpler. I was actually able to use the stock GMC oil feed line. I had to 'unbend' the turbo end of the line a little and rotate the fitting in the hose crimp. I fabricated a block with a piece of 1/8 pipe bent to clear the turbo output elbow. 

Rack and pinion kit

In the process of laying out the dump pipe for the turbo I realized that the steering idler arm was going to make the exhaust routing difficult. On right hand turns the idler arm swings into the space I wanted to use for routing the pipe. Yeah, the pipe could be made to snake around it but it was going to be tricky getting it right. I had planned (later on in the project) to toss the stock steering system and replace it with a Steeroids rack and pinion kit. I didn't want to do that until after the car was drivable but the kit eliminates the idler arm and frees up space for the exhaust pipe. So, on goes the Steeroids kit so I can get on with finishing the exhaust.

There's the rack. It's so much nicer than the original steering box and hydraulic cylinder. Installation was super simple an easy. That hardest part was working the old steering box out from between the left exhaust manifold and the frame.

Now there's just enough room for the exhaust to pass between the motor mount and steering rack without a bunch of additional bends.

Turbo and intake pipe mounted

It's more fun to work on stuff that shows. It makes it look like progress in being made.
The turbo is in place and the intake tubing is arranged.

Next I have to get fresh cool air into the turbo. I made a panel that mounts where the original radiator did just above the top of the new radiator. The new panel will hold a big K&N air filter (from a Lamborghini) and route filtered air from in front of the radiator directly into the turbo.  That means having a pretty tight 90 degree elbow that has to clear the left side upper control arm and the upper radiator hose. After collecting a big box of metal and plastic elbows to try to modify I decided I had to fabricate the elbow out of fiberglass.

Starting with a flat sheet of Styrofoam, I cut a bunch of 4" diameter cookies with a hole saw.
Then I sanded each cookie into a wedge. It was pretty simple to glue the wedges together to form approximate shape of the elbow.

 

After hours of gluing and sanding and test fitting I covered the foam plug with fiberglass and epoxy resin. With a couple more layers of fiberglass and lots more sanding and shaping We have an elbow. It fits just right and has the clearance it needs.

Water manifold

The 6.5 has a big Y shaped casting to route water exiting the cylinder heads through the thermostat and on to the radiator. It also has hose connections for the thermostat bypass and heater supply hose. My problem is the stock water manifold is too tall. With it installed the hood can't close. In addition the filler cap needs to be the highest point in the system. With the radiator mounted so low I would have to fab an additional filler of some kind at the top of the water manifold. Several attempts to modify the stock manifold were not satisfactory so I decided to fabricate a water box.

So far, so good. It's got all the necessary connections, the filler is at the top so it will be easy to purge air from the system. There is a baffle inside to help mix the water from left and right heads. The thermostat is inside the big fitting on the left of the photo. The fitting unscrews and the thermostat fits inside.

Exhaust from the motor to the turbo

It's taken quite a long time to get the most critical part of the exhaust system fabricated. There's just barely room for the necessary piping so precision was critical. Finally all the exhaust that connects from the exhaust ports to the turbo inlet is done. Exhaust crosses over from the right side to the left and then runs forward to the turbo in front of the engine. Here it is assembled on the floor.

It's welded out of 1/8" thick stainless steel tube with v-band connections to ease installation and flex couplings to avoid cracking from heat stresses.

I used up a lot of time and stainless steel tube making parts that weren't quite good enough. The first attempt at the manifolds warped so much during welding that I just had to scrap them and start over. I learned a lot about welding stainless though so it wasn't a complete loss. The next step is to wrap it up with exhaust wrap and then it can be bolted up.

Turbo placement

Before I can get much of the exhaust fabrication done the turbo location has to be determined.
Moving the radiator down and forward left just enough space for the turbo to sit right in front of the motor.

It's a pretty tight squeeze with only about 3/4" clearance from the power steering pump, upper control arm and top of radiator but it will be fine. This is not the crappy original GM-1 turbo. After many hours of research I settled on a Holset WH1C. This turbo was used on early Dodge Cummins pickups.

It's supported with a bracket attached to the front crossmember.

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.