Gil exhaust question
 

Hi everyone,

I purchased a 98 HP500 with factory Gil exhaust last summer. There is a "y" pipe in the exhaust and I was wondering what purpose it serves. The pipe goes down under the engine. I originally thought it was for a silent running option, but I didn't see any actuators etc, that would lead me to believe that there is a moving part inside. Am I missing something really obvious?

Thanks!

Does your exhaust exit through the transom or through the prop? There are some set ups that do both and are not switchable as would be with silent choice/captians call. If the top of the y pipe is connected to the exhaust then it is my assumption some or all exhaust goes through the prop. If by chance the tops of the y pipe are not connected then they should be capped off and I would guess at that point the boat came from the factory with through prop and a previous owner changed to through transom and did not remove the engine to remove the now unused y pipe.

Not sure what you mean, but the Y pipe attaches to the transom assembly for the exhaust to exit through the outdrive and below the water line. Some exhaust setups have a diverter that does not have any moving parts (quick and quiet) that attaches to the Y pipe and thru hull allowing the exhaust to exit at both locations at the same time. Some have a diverter with movable flap inside controlled by a solenoid (silent choice).

Thanks for the quick response. The exhaust exits through the transom above the water line without mufflers right now. I have not run the boat out of the water to verify if any exhaust is going thru the prop.

Research Corsa Quick & Quiet II and see if what you have looks like it. If so then it goes both through hull above waterline and through prop via the y pipe.

Good chance the previous owner added the Gill exhaust and didn't remove the Y-Pipe. Happens all the time.

Edit in: ooops. You bought the motor , not a boat. Sorry.

And if it is a HP 500 carbed engine it has Mercruiser/Gil exhaust from the factory.

Correct. I read the original post wrong. Typical for me. And thus my edit. LOL.

ok; is this y pipe on your boat? or the new motor? many-most crownlines are thru prop exhaust. is there another y-pipe connecting the thru transom exhaust to the downpipe? or does it go straight over the top of the downpipe? crownies with thru hull usually have captain's call-silent choice type setups on them. or somebody got a hole saw and changed the exhaust over to thru hull.

The idea behind the Quick 'n Quiet setup was a diverter that directed exhaust both through the transom (typically with muffled tips) and though the prop via the Y-pipe attached to the transom assembly. The idea was that at idle and low speeds more of the exhaust would go through the prop to help quiet it down, and as exhaust pressure increases with RPM's, more of it would flow out the transom tips. Keep in mind that at speed the area around the prop actually creates a low pressure area that helps to draw more exhaust out the prop, but at the same time you have a restriction through the transom assembly of about 2x3 inches. I don't think it hurts to have the Quick 'n Quiet, as long as your risers dump the water far enough back to prevent reversion with the cam you are running.