PDA

View Full Version : Switchable exhaust idea-good, bad or not!



The X Man
09-18-2009, 02:38 PM
Is this wacky or totally off base??????
I've been thinking (and thats dangerous) about setting up my 18 project with switchable exhaust, but both options going through the hull. One would be a straight pipe and loud, the other through a muffler for legal but still a nice sound. I don't know if I can fit it in side the engine compartment and join them back together before the tip or if I'll need two tips on each side. Is this way out there or is it feasible? Anyone tried it?

Last Tango
09-18-2009, 03:10 PM
Although, right now I'm leaning a bit to the "wacky" side, you could avoid the 4 exhaust tips thing by simply putting pairs of the switched exhausts through a single tip on each side. It would necessitate a crossover pipe from each side but you are already thinking about a lot of extra tubing running around the engine compartment. Might be cheaper and easier to just suck it up and go traditional with the Quiet cut-off pipes running straight into the water from the hull (through a y-tube) rather than through the outdrive. Either way, there is going to be a lot of fat, shiny spaghetti in the engine compartment.

MOP
09-18-2009, 04:01 PM
What about going with Q&Q? Or using one of the various inserts, I was surprised how much a twisted piece of stainless shoved inside the pipe quiets things down.

Dr. David Fleming
09-19-2009, 03:31 PM
I don't know how many off shore boats you have seen but many have a muffler on each side of the transom that has a shutter on the end that opens for that good old noise.

Custom Marine - CMI sells the stainless headers and all the exhaust equipment - straight tips no baffles - straight tips with shutter that opens with backpressure in the exhaust - shotgun back firing mufflers with air cylinder on the side that allow you to open her up! Also the new e-mufflers I think they are called that just open themselves up. And for old school guys they sell diverters under the name of "Silent Choice" that pipe the exhaust under the water into the propeller hub.

Corsa makes most of the Donzi exhaust options under the name of "Quick Quiet" which is an electrical diverter for each side of the engine. They also make most of Donzi exhaust tips or mufflers on the transom. The ones with the little Sallisbury (sp) rubber flap - these have a baffle you can take out.

If you go with the diverters you have to have the Mercruiser part that is like a big cast aluminum exhaust collector that goes under the engine - Merc calls this the "bullhorn." There is a rubber boot or gator that connects the exhaust from the transom bracket to the drive unit so it can go out the center of the propellor hub. Some high performance Mercruiser engines don't use the gator because of the prop backwash or suction - they use the boot which basically just dumps the exhaust under water- not through the prop.

If you don't have the bullhorn you have to take the engine out to install it - there is a Mercury block-off plate that goes over the opening so the boat doesn't sink. You can check out all these parts online on one of the Mercury parts systems available at major marine dealers.

I wouldn't think you would want to make your own exhaust components because most have water cooling or are designed to not be a fire hazard in a boat - ever seen fiberglass burn - you don't want to!

Dr. d

The Hedgehog
09-19-2009, 11:20 PM
So you don't want switchable tips sticking out? I am sure that you could run some corse diverters and turns inside the boat. It will be tight and you should measure them first.

Different but doable. I am always up for a new idea.