Originally Posted by sphippler
How long does my exhaust have to be. Im not talking about legal or safety reasons. Im talking about performance and not damaging the engine. I have a 304 with 2.25" dia pipe and no muffler or catalytic converter. I've heard that if the pipe is too short that it can damage the engine.
Theoretically, the exhaust manifold should
be long enough to prevent damage (the "damage" you've heard about would be cool ambient air getting sucked back in between exhaust gas pulses, which would warp exhaust valves rather rapidly.)
Since you've got a V8, I'd go so far as to run back to a cross-over pipe (helps with scavenging, since each bank can assist the other,) and then install a spark arrestor on the ends of the pipes (I'm assuming you're off-road only, from what you've said?)
There would be no harm in installing a cat on each pipe - something from Random Technologies, perhaps - as it would show "environmental consciousness" and (hopefully) make a couple of greenies' heads explode! However, even with the cat, you'd still need to install a spark arrestor on the after end - but that may simply be moved from cat to cat, if/when they plug up.