In Part 3 of this story series on the high-mileage 6.0 turbo, Craig is going over his steps for installing the wastegates on the system. Craig is using T4 flanges for the wastegates and details the install.
Locating the Wastegates on the Manifold-Turbo Pipes
The wastegate has to be installed between the manifold and the T4 flange so as to vent the excess exhaust pressure before it hits the turbo. Craig reminds us that it must also be installed in such a way that you can route the dump pipe well away from the turbo intake. Not doing so will cause the turbo(s) to ingest spent exhaust gasses and this can become problematic.
Craig installed his wastegates somewhat close to the flanges and oriented in such a way that he could route the dump pipes out the fenderwells. This will cause a bit of soot buildup on the wheels and tires, but we wash our cars pretty regularly, right?
For looks, Craig wanted the wastegates to be perpendicular with the turbos. You don’t have to if you don’t want to; Craig just thinks it looks better this way. He also says you can simply weld the wastegate flange directly to the pipe, just be careful to not interfere with the lip for the V-clamp that secures the wastegate to the flange.
He first cut two three inch sections of 2 ¼-inch exhaust pipe (your twin turbo system may require a different size). He then placed one of these on the passenger side pipe just before the T4 flange and marked the top with a marker and removed the manifold.
With the manifold assembly locked in his vise, Craig placed the upper portion of the pipe section on his mark and rocked it down so he could mark the lower portion. He then struck the exact center between these two marks with a center punch (to keep his drill from wandering). Using a 2 ½-inch holesaw, he then cut the opening out for the wastegate pipe.
Attaching the Wastegate Extension Pipe to the Manifold-Turbo Pipe
Next, the extension pipe was tapped into this opening with a block of wood and a hammer. Using a marker, he then drew around the extension to mark where it met the manifold pipe and removed the extension. He then used tin snips to cut what he calls an “eyebrow” into the extension pipe along this line. This allows the two pipes to match up better and creates a much smaller gap for you to fill. With the “eyebrow(s)” cut out, the extension was again tapped into the opening. If you cut the eyebrow properly and tap the extension in far enough, you’ll limit the gap(s) between the two pieces of pipe that you’ll need to fill by welding.
Unless you’re pretty lucky, there’s always going to be at least some small gaps between these two pieces no matter what you do. Small gaps can be filled by “burping” your MIG welder along the edges of the gaps after tacking the two pipes together. Craig prefers to cut little strips of pipe from the circle he cut out and tacking and tapping these into place. Once this is done, run a solid bead around the circumference of the wastegate extension pipe and be sure it’s completely airtight. Looking down inside the pipe, if you see a lip after you’re all welded up, you will need to use your die grinder with a cutting tip to cut it/them out so as to not obstruct the flow of exhaust into the turbo.
Attaching the Wastegate Flange to the Extension Pipe
The wastegate flange is a solid ring of stainless steel. Normally you’re not supposed to weld stainless to the mild steel that the exhaust pipes are made of. Again, Craig is doing a budget build, so we aren’t going to worry about this. What Craig does is focus the heat on the extreme lower portion of the flange and allow the puddle to run down to fill the gap between the flange and the pipe.
Firmly clamp the manifold assembly so the wastegate opening is parallel to the ground and place the flange on it, narrow side down. Tack the flange to the extension in a couple places to keep it from shifting. Double check your work, making sure the two pieces are as flush as they can be. Carefully run your full bead around this joint. Again, be sure you don’t interfere with the V-clamp portion of the flange. Clock your wastegate so you can get to the vacuum port and the dump tube port and securely clamp it in place using the V-clamp supplied with your turbo/wastegate kit.
Installing the Dump Tube on the Wastegate
Craig normally likes to drop the dump tube straight down until it reaches an inch or so below the frame. However, to make things easier for himself and because there were things he didn’t want to have rubbing against the dump tube (which gets hot), he decided to route the dump tube out the fenderwells.
Since the JSRP parts truck has the stock rubber engine mounts, there’s going to be some give in the mounts, especially when the accelerator pedal is mashed to the floor. For this reason, Craig went with flexible exhaust pipe instead of rigid. This allows him to make the hole in the fenderwell as small as possible; in this case 2 ¾ inches in diameter.
To connect this to the dump tube flange, he used a rigid 1 ¾ to 1 7/8 inch expander/reducer. The 1 ¾ side fits perfectly inside the notch in the flange on the dump side and the 1 7/8 OD flex pipe fits perfectly in the 1 7/8 side of the expander/reducer.
Craig slid the flex pipe as far into the expander/reducer as it would go and tacked it into place in four locations. The fit is so good that it doesn’t need to have a bead run around the circumference and trying to run a bead runs the risk of burning through the light steel of the flex pipe. He then ran a full bead between the flange and expander/reducer, taking extreme care to not interfere with where the V-clamp will sit.
Prior to connecting the dump tube to the wastegate, Craig used his two inch hole saw and drilled through the fenderwell where he wanted the dump tube to exit. He then routed the end of the dump tube through this hole and clamped the other end to the wastegate. That completed the passenger side. To finish the installation of the wastegates on his twin turbo setup, he simply repeated on the driver side.
We’re going to follow along with Craig as he removes the old OEM single return-less fuel pump from the tank and replaces with dual fuel pumps.