When performing a V6 or V8 engine swap into a Toyota truck, one area that requires a bit more effort is the exhaust. When installing a Buick V6 or a Ford V6 or V8 engine there is adequate space between the engine and frame rails, but when using a Chevy V6 or V8 engine the space is tighter. In these cases, stock Chevy cast iron manifolds usually will not fit because of interference between the collector flanges and the frame rails.
There are several aftermarket conversion headers available to solve this problem. One type, referred to as a Slick-Fit, is a compact design that fits very close to the engine and uses rear dump collectors on each side. The exhaust port runners dump immediately into a collector at rear most cylinder.
Other aftermarket headers are available that are longer and generally use a 3-into-1 or 4-into-1 design. These headers use long primary runners that converge into a collector between the frame rails to the sides of the transmission.
One other option is to use modified factory Chevy headers on the swap. Over the years, several GM vehicles have used factory tubular headers on V6 and V8 engines. These tubular manifolds can be modified to clear the truck frame rails. This involves removing the end flanges and lengthening the tubing sections before reattaching the flanges further down past the frame rails.
Fuel injected engines that require use of an oxygen sensor will need to have a threaded fitting installed in the proper place in the exhaust tubing. These are placed in either one or both legs of the Y-pipe, or further past the Y-pipe junction. An original application for the engine should be studied and the conversion installation should duplicate the sensor position as close as possible. Note that changes in other exhaust components in the system can affect performance of the oxygen sensor.
