exhaust manifolds

[dgie]

Just curious if anyone knows, is it possible to take a regular set of exhaust manafolds for a small block chevy. drill some ports and install some water injectors to cool the exhaust, this is a Through The Transom setup of course. If this method would work it would be much cheaper to convert these automotive manifolds as opposed to dropping the big bills on marine ones.

[HOSS]

Sounds like an idea. Try it and let us know what happens.
:D

[TexasJet]

devil HOSS you are a BAD man.

[DUCKY]

Since no one else want to tell you, NO, don't do it. The automotive manifolds do not have the necesary drop in them near the ports to allow any standing water to drain, chances are that you will get water in the motor. I did see someone run auto manifolds dry, then put bungs in for water dumps in the pipes, right before the exhaust hose, it worked, but the manifolds will get hotter than hell, and the cast iron does not cool down quickly. Your best bet is to get the right exhaust.

[Chris J]

No sure if it'll work, but if you get a set off a pickup they have about a 2" drop at the ports (spark plugs are located above the manifolds). Find a set from the early 70's that had an air pump and they'll already be tapped and plumbed with tubbing.
However most cast marine manifolds are water jacketed and circulate the water around the manifold to preheat it before it enters the motor. The water is actually injected at the snails not the exhaust mainfolds. Also cast iron doesn't transfer heat as well and you could create hot spots which could promote cracking which is a problem on car & trucks now. Of coarse a car never sank due to a cracked exhaust manifold. If your exhaust is above the water line what the hell give it a try. If not I'd pass.