doesn't want to run over 2000 rpm's
09-07-2009 | 05:08 PM
#1
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From: Forest, Va
doesn't want to run over 2000 rpm's
Someone explain this to me. I have a 2004 fountain 29' with a single 500 hp and xr 1.5r drive. It has headers with a Y pipe so the exhaust goes down into the water but also goes straight back thru the transom into mufflers that are about 18" long. This is a factory setup. This was to quiet for me... I wanted some noise,,, so I took the Y pipe off and made all of the parts I needed to install corsa solenoids and flaps to convert this to silent choice. I took the mufflers off and installed tailpipes with external rubber flaps. I had a set of corsa exhaust laying in the garage but it would not fit on this fountain exhaust set up, so I used the solenoids and flaps and made the shaft bushings and brackets to convert the fountain factory Y pipe to a silent choice. This is what I dont understand,,,, If the exhaust is closed (running quiet) and I try to throttle up to get on plane, the engine will not go over 2000 rpm. Flip the exhaust open (loud) and the boat jumps up on plane. Is this because the exhaust going into the water is to restricted and the exhaust gases cannot excape to allow the engine to run ? If so, why is it to small and can I fix it so I can run the silent choice (quiet) when I am cruising ? I also have a 2000 fountain 27' with a 502 mag mpi with b1 outdrive with factory corsa silent choice and I can run it (quiet or loud) anytime I want to with no problems. Is there a difference in the size of the down pipe on the 2 boats ? Or is it a difference in the 2 drives, xr and bravo ?
09-07-2009 | 05:58 PM
#2
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Joined: Aug 2005
Posts: 6,306
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From: Between A Womans Leggs in IL
mrfixxall
Someone explain this to me. I have a 2004 fountain 29' with a single 500 hp and xr 1.5r drive. It has headers with a Y pipe so the exhaust goes down into the water but also goes straight back thru the transom into mufflers that are about 18" long. This is a factory setup. This was to quiet for me... I wanted some noise,,, so I took the Y pipe off and made all of the parts I needed to install corsa solenoids and flaps to convert this to silent choice. I took the mufflers off and installed tailpipes with external rubber flaps. I had a set of corsa exhaust laying in the garage but it would not fit on this fountain exhaust set up, so I used the solenoids and flaps and made the shaft bushings and brackets to convert the fountain factory Y pipe to a silent choice. This is what I dont understand,,,, If the exhaust is closed (running quiet) and I try to throttle up to get on plane, the engine will not go over 2000 rpm. Flip the exhaust open (loud) and the boat jumps up on plane. Is this because the exhaust going into the water is to restricted and the exhaust gases cannot excape to allow the engine to run ? If so, why is it to small and can I fix it so I can run the silent choice (quiet) when I am cruising ? I also have a 2000 fountain 27' with a 502 mag mpi with b1 outdrive with factory corsa silent choice and I can run it (quiet or loud) anytime I want to with no problems. Is there a difference in the size of the down pipe on the 2 boats ? Or is it a difference in the 2 drives, xr and bravo ?
i wouldnt run the boat over 1500 rpms with your set up and cmi makes special type of corsa(their own version) captains call for their headers..
heres some pics of the the diverters,,you may need to be a member to see them tho..or give me your em and i can mail the pics to you.
http://www.donzi.net/forums/showthread.php?t=57658
Last edited by FIXX; 09-07-2009 at 06:10 PM.
