I recently have been working on a 83 turbo carbed car for a customer. The car is in good shape with a recent rebuild of the motor and the trans. Customer was looking for some upgrades as well as some general tuning to get a "little" more out of his car. I figured the best upgrade for his situation was a better downpipe. He already has a muffler shop dual exhaust and a stock cat that has been modified internally to be as free flowing as possible. here are a few pictures of the downpipe. Since a 84-85 is very similar I figured those guys could benefit as well. The lack of ready made alternatives forced us to build our own. Total downpipe was made from 3 u-bends bought through Jegs for $15 each. $45 in materials, but a whole day in fabrication time. You can almost make it with two u-bends, but the first bend from the turbo outlet is a little more than 90 degrees. I was able to make it in one piece and can install it just by removing the passenger exhaust manifold and installing them both together. I think you could really work at it and clear a 3 inch downpipe, but it may have to be two pieces to be able to install it without pulling the motor and I don't see the benefit on a hot air car to justify the extra work and expense.
Here you can see the inlets from a stock compared to the 2.5 downpipe. Much better
Same results on the outlet at the cat flange. I went ahead and made the exhaust flange out of some scrap metal I had versus trying to reuse the factory one.
I went ahead and reused the upper flange instead of trying to make one. When I cut the factory downpipe I was suprised to find it double walled. I guess they used a 2.25 pipe inside of a 2.5 pipe and bent them both to help keep from crushing the tubes from the factory? So now we are talking a crush bent 2.25 downpiep being replaced by a mandrel bent 2.5 downpipe.
Here is the stub for the turbo outlet. I also ported the elbow out as well as opened up the wategate hole another 1/4 inch to 3/4 to match the puck better. This elbow isn't really that bad. More of a 45 degree outlet versus the 90 of a 84-87 turbo, but they have much better wategate setups.
Greg Kring
Arlington, Tx
2002 BG super 16 winner
ex buick owner
Here you can see the inlets from a stock compared to the 2.5 downpipe. Much better
Same results on the outlet at the cat flange. I went ahead and made the exhaust flange out of some scrap metal I had versus trying to reuse the factory one.
I went ahead and reused the upper flange instead of trying to make one. When I cut the factory downpipe I was suprised to find it double walled. I guess they used a 2.25 pipe inside of a 2.5 pipe and bent them both to help keep from crushing the tubes from the factory? So now we are talking a crush bent 2.25 downpiep being replaced by a mandrel bent 2.5 downpipe.
Here is the stub for the turbo outlet. I also ported the elbow out as well as opened up the wategate hole another 1/4 inch to 3/4 to match the puck better. This elbow isn't really that bad. More of a 45 degree outlet versus the 90 of a 84-87 turbo, but they have much better wategate setups.
Greg Kring
Arlington, Tx
2002 BG super 16 winner
ex buick owner
