Capped off pipe

[sdoan]

DeeJay,

That opening you have the arrow pointing at is for the heat riser - old manuals sometimes referred to it as a stove. The way it works is that a steel box around the cast iron exhaust manifold traps heat to help warm the air going into a cold engine. The exhaust gases all go out the tail pipe like you'd expect so no exhaust will come out of the heat riser. But the box traps warm air for the engine. The opening is meant to have a high temp accordion hose up to the air cleaner snorkel where there is a thermostatically controlled vane. When the engine is cold the vane diverts warm air from around the exhaust manifold up into the air cleaner and engine. When the engine warms up the vane blocks warm air from the manifold and takes it from the front of the car through the rubber hose on the end of the air cleaner snorkel.

[deejay1272]

Sdoan - Thanks for the explanation. This clears it up nicely for me. I've decided to service the components of my HAI system and re-connect the riser port to the bottom of my intake (to complete the HAI system/circuit). This ought to help me achieve warmer engine temps sooner than present, and thus improve fuel economy too!