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Switchable Exhaust - Why?

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Old 08-15-2006, 11:46 AM
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Default Switchable Exhaust - Why?

My 454 Mag MPI (Bravo-1) has a Captains Call switchable exhaust capability and I am wondering about the benefit, if any, of the feature ... other than sound level.

I understand increased horsepower due to less airflow restriction when using the pipes rather than the drive , but how much of a horsepower gain is actually realized, and at what RPM level? Are there any additional benefits when routing the exhaust directly thru the pipes?

Are there any particular drawbacks when routing the exhaust thru the outdrive? At higher RPMs, does the restricted airflow cause any damage, or simply affect power output? Since most all Bravo-1s have a drive exhaust capability, is it fair to assume that using the outdrive exhaust regularly will not negatively impact the engine?
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Old 08-15-2006, 11:50 AM
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Default Re: Switchable Exhaust - Why?

I love the sound! But need to make her quiet for the police. So I love the option! Use it alot!
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Old 08-15-2006, 12:20 PM
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Default Re: Switchable Exhaust - Why?

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Originally Posted by Canada Jeff
I love the sound! But need to make her quiet for the police. So I love the option! Use it alot!
what jeff said.
todd
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Old 08-15-2006, 12:39 PM
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Default Re: Switchable Exhaust - Why?

Through the prop puts a lot more heat into the outdrive which may affect life. I read somewhere (cant find it) that it's recommended with switchable exhaust setup that you don't go silent above 3500-3800rpm.
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Old 08-15-2006, 12:49 PM
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Default Re: Switchable Exhaust - Why?

My Teague's switchable said never to run them over 3,500RPM, and was counseled to try and keep it never above 3,000 RPM in the closed position. Top end difference between full time mufflers (Corsa at the time) and then straight pipes was around 250 RPM and possibly 2-3MPH. But the sound!!!
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Old 08-15-2006, 01:17 PM
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Default Re: Switchable Exhaust - Why?

Makes sense that heat build-up above 3000-3500rpms could cause potential problems, but it would seem that a drive shower would potentially offset that concern.

If running in silent mode could damage your engine, I doubt Mercruiser would let it be installed by the boat builders. Since Brunswick owns Mercruiser, Baja, etc., it would seem that if adding exhaust diverters at the factory could cause damage to a Mercruiser engine, then some serious quality control questions would arise.

I brought up this subject because many times, guests are not quite as enthusiastic about the sound of open pipes as we speed demons! Although they enjoy going fast, the roar of a big block engine is definately an acquired taste!
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Old 08-15-2006, 01:27 PM
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Default Re: Switchable Exhaust - Why?

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Originally Posted by [email protected]
Makes sense that heat build-up above 3000-3500rpms could cause potential problems, but it would seem that a drive shower would potentially offset that concern.

If running in silent mode could damage your engine, I doubt Mercruiser would let it be installed by the boat builders. Since Brunswick owns Mercruiser, Baja, etc., it would seem that if adding exhaust diverters at the factory could cause damage to a Mercruiser engine, then some serious quality control questions would arise.

I brought up this subject because many times, guests are not quite as enthusiastic about the sound of open pipes as we speed demons! Although they enjoy going fast, the roar of a big block engine is definately an acquired taste!
I love the sound of open pipes, but wish I had room for switchable exhaust. I really enjoy a sunset ride at 40-50 mph on my buddies boat that has that option. Very pleasant and the women particularly like it.

He has run it WFO in silent mode several times over the years, hasn't caused him any problems. (560hp 509 BBC)
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Old 08-15-2006, 02:24 PM
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Default Re: Switchable Exhaust - Why?

Thank you all for your input, and I appreciate your concerns and suggestions. My intent was not to create a referendum on performance, but to understand the ramifications of using a great feature of my Baja.

Although my wife and I enjoy the power and roar of open pipes, we found it to be quite relaxing when we cruised along at about 3500rpms in the silent mode. She suggested we go faster, but I was concerned with what would occur if we did.

There seems to be a time and place for everything .....
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Old 08-15-2006, 02:54 PM
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Default Re: Switchable Exhaust - Why?

I have it on both of my motors and love it. I was told not to go over 2500 rpm in quiet mode. Does anyone actually have something in writing on this?

Pretty much use mine when coming into the marina, dock no wake zones. Pretty much anytime not on plane. Unless there are some hot chicks of course, then it is loud. I use to call it the "panty dropper switch" My wife wasn't impressed with that so I stopped that sh!t.
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Old 08-15-2006, 03:01 PM
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Default Re: Switchable Exhaust - Why?

only time i find it useful is if the water cops are around or people that ***** at noise...it's nice to have, but i hardly ever use it
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