Turbo System Fabrication

The original turbo system I built for this car had a very restrictive front-exhaust downpipe that not only caused exhaust backpressure but also added tremendous heat to the engine compartment. The new system follows the normal rear-outlet exhaust routing of a FWD V6 car. Getting the exact angle of the exhaust outlet was tough. I had to tack-weld the exhaust outlet elbow into place with the engine in the car, then remove the engine being careful not to knock off the tack welded piece!

Here is the exhaust elbow carefully tack-welded in place in exactly the right position.

Now, the bolt-together bracket has been welded onto the manifold blanking-off plate (which capps off the factory exhaust outlet) and the outlet elbow. The tack weld was then ground away. I wanted a bolt-together brakcet so the exhaust system could be removed without engine removal if needed. Also it gave some flexibility if the angles were alittle bit off. The exhaust flange has been installed at this time. The companion flange is connected to the pipe leading back to the mufflers.

Here you can see the completed downpipe, welded together to the outlet elbow. The pipe is not welded to the turbo/ wategate weldment. These are allowed to move for an expansion joint.

Here is the exhaust crossover weldment which joins the front and rear exhaust manifolds together, and supports the turbo. This part must withstand tremendous heat while supporting the heavy turbocharger assembly. It has an expansion joint allowing the rear bank exhaust inlet to move a little. The pipe is telescoped inside its self and the stainless flex pipe is just an outer covering to minimize exhaust leakage.

This odd looking thing is the weldment that bolts to the turbine housing outlet and mounts the Turbonetics Evolution wastegate. It may look "agricultural" but that doesn't slow the car down any!

This is how it all goes together. The wastegate valve, turbocharger, and wastegate weldment.

Since this turbo is a water-cooled unit, I had to design and install coolant lines. Here you can see the two coolant lines (silver 3/8" tubes going to the left), the oil supply (green 1/4" steel tube at top of turbo), and oil return (1/2" copper line at bottom). All the tubes are 45° SAE flare, double-flared. Some are IF fittings and some are conventional "gas" flare.

This is where the coolant lines originate. The supply line originates at the heater hose fitting. It gets pressurized coolant ffom below the thermostat. There is coolant flow here regardless of thermostat opening or closing. The return from the turbo goes into a fitting I added to the timing gear case. This is a direct return to the suction side of the water pump. I drilled and tapped a 3/8 NPT hole and installed a brass fitting to accept the flared line.

Here's the completed turbo system installed with fiberglass insulation over the crossover and downpipe. The fiberglass insulation has been overwrapped with aluminum and retained with stainless tiewraps. This system has dramatically less underhood heat as the original turbo system had! This one had to be extra well insulated because it is near to the brake master cylinder and compromising that part is not an option.