Looking a running twin turbos on my 454s in my cat. Pushing kaama surface drives. My plan is to run a blow thru twin turbo set up. My question is does water come out of the exhaust ports on the block? If thats a no does water enter the manifold or is there a pump inline on the exhaust after the riser? I guess my question is i dont want any water entering the turbines on the turbo where it should be all air. Thanks in advance

No water does not enter the manifold VIA the exhaust ports on the head. Typically the water enters the manifolds from hoses coming off the thermostat housing some people even run dry exhaust where the water never mixes with the exhaust gases. The insides of "wet" manifolds are jacketed and the water does not mix with the exhaust gases until it is in the tail or down pipe leaving the boat. To run turbos you will likely require custom manifolds to make it work I don't believe its possible to just add them to a standard style exhaust.

Fireckn ive been reading a bunch online but nobody really has done any turbo set ups on boats except for jet boats. Most of them are car engines. If its a blow thru use the gil marine manifolds i have now, Weld a turbo flange on them, and my plans are to run an intercooler. Help with cooling.

The Gil Down pipes typically are double walled and have a thin channel for the water to run between the walls and then holes at the ends for the water to mix back in with the exhaust before coming out the exhaust tip. It would be very difficult to modify those pipes to still function and be usable with a turbo. I would also be very concerned with the any vacuum the turbo would create that close to the water mixture causing reversion and sucking the water back toward the turbo. If you really want to go with a turbo setup you should really look into running dry exhaust

There have been marine 454 turbo setups for years, they are just not popular. With enough digging you should find info, parts, setups etc... Some fountains ran them back in the day.

Converting an old school Gale Banks Twin Turbo system to modern technology

Old School Gale Banks Twin Turbo Setup

Complete twin turbo set up with manifolds $700 on West Palm Beach Craigslist. This might help you get started. Good luck.