Buick Turbo - Power Trip - Tech

I'll be utilizing Turbonetics' Racegate external wastegate (PN 10307, $496). This 'gate is superior to a stock-style 'gate in several ways: it is a 1.80-inch, stainless steel valve compared to a "puck"-style wastegate with a hole of less than an inch; the Racegate is fully closed until it is actuated; the stock-type is open a little, which affects spoolup. Finally, one spring in the Racegate will give 9-30 psi boost, offering a much wider range of adjustment than a stock-style wastegate.

My current 3-inch, Houston-style downpipe with dump pipe has been a great upgrade, but at 550-plus rwhp and 25-plus psi of boost, I'm now leaving power on the table. Brian Cotton lifts the T up and removes my current 3-inch downpipe by unbolting it from the exhaust system down below, unbolting it from the turbo, and pulling it out.

Cotton also removes the shield by the heater box. This extra clearance isn't needed for a 3-inch downpipe, but it is necessary for a 3.5.

We'll be swapping that 3-inch pipe for a custom stainless 3.5-inch Cotton's Performance downpipe ($699). Cotton's Performance offers standard external wastegate 3-, 3.5-, and 4-inch downpipes, and is also in the process of creating a production 3.5-inch downpipe to fit most every header out there, and use whatever flange is needed for the customer's turbo. Contact Jack for more details.

For this story I get to sit back and watch as Brian fabricates a 3.5-inch 'pipe to work with my TA Performance headers...

...Jack says, "Hey Scott Scrivner-sorry! We ran into a fitment issue but were able to make easy mods to this downpipe for Jensen's TA Performance header'd car." Nothing like stealing some poor guy's parts for the sake of editorial.

A hole is cut into the TA header to mount the wastegate tubing.

Brian cuts and welds the pipes needed to mount the external wastegate. He tacks the pipes in place first, and verifies that the angle will work in my engine bay.

Here's the engine bay, all ready for the new downpipe. Note the relocated IAT sensor in the upper plenum.