can you bypass exhaust through the270 sterndrive

Hi All,
I have a 351w being built with about 260 hp--max hp for the Volvo 270 exhaust. Can I disconnect the exhaust baffle hose from the stern drive and let the exhaust out the end of the baffle hose? would water back up the y exhaust pipes be a problem? Do I install a exhaust flapper on the end of the baffle hose? would there be a lot of noise or would the water quiet the exhaust noise some? Max hp at WOT about 245 hp
Thanks,
Tmcboat

Baffle hose = exhaust bellows???????

If so, DO NOT disconnect the exhaust bellows from the Y-pipe nor from the Intermediate housing.... it will create issues.

The 270 lower unit exhaust outlet fitting is equipped with a back flow prevention flapper. Make sure that it's OK.

DO NOT use the exhaust bellows with the internal flapper...... these are too restrictive for V-8 engine exhaust flow.... IMO.



Re; the 351 Windsar for True Marine use.

The 5.8L cylinder head exhaust ports are too small for any decent Marine Engine performance.
I'd open up the exhaust ports and go with larger exhaust valves.

The combustion chambers are similar to that of the SBC in that they offer a quench surface off to the side of the main chamber.
I'd use a piston profile that allows for a good quench dimension within the combustion chamber.

Not an automotive quench dimension.... use a quench dimension that is suitable for the Marine version.
The SBC can be as tight as .038".



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