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?

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!

Re: Switchable Exhaust - Why?
 

what jeff said.
todd

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.

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!!! :drink: :evilb: :drink:

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!

Re: Switchable Exhaust - Why?
 

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)

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 .....

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.

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

Re: Switchable Exhaust - Why?
 

I read long ago that running with it closed at high RPM will burn the rubber off the flappers. Of coarse I can't confirm that.

Re: Switchable Exhaust - Why?
 

I just spoke with a Joanne @ Mercruiser (405-743-6566 option-4) regarding the silent choice option, and routing the exhaust directly thru the Bravo-1 drive.

"There is no predictable negative engine impact other than a minimal power loss due to airflow restriction and backpressure when using the outdrive exhaust option."

I then asked about cruising at 4000-4500rpms and she simply reiterated her comment. Her final thought was "to get the maximum performance from the boat, use the pipes, but for maximum comfort, use the outdrive option ..... that's why we put it there!"

Re: Switchable Exhaust - Why?
 

Why ????
Because we can and to be cool. :evilb:

Re: Switchable Exhaust - Why?
 

Lot's of boats run without thru hull exhaust. Should be no diff.

Re: Switchable Exhaust - Why?
 

I like my Corsa, but only after I installed them did I find out that they are Illegal in Florida. I switch them off when not on plane, so far so good.

Also,
I found that with them switched off for testing purposes, you can actually hear the engine's internal workings better and can detect detonation easier when they are used.

Re: Switchable Exhaust - Why?
 

Never heard of any damage and it should be a non issue with fuel injection, carb motors may run a fraction fatter, which should still not be a problem.

Re: Switchable Exhaust - Why?
 

Main problem I have noticed on my buddies boat with silent choice is that we can hear our wives talking :evilb:

Re: Switchable Exhaust - Why?
 

Yes, that is why when I go on plane, and open them up, it gets real quiet on the verbal front, sometimes I just leave them open when I have to come off plane to pass under a bridge in a no wake zone, so as to not break the spell.

Let's see, cammed up BBC's or chatter about non-sense stuff,,what to do, what to do. My version of "peace and quiet".

Re: Switchable Exhaust - Why?
 

I enjoyed it on my last boat because I could quiet it down at cruise speed and not have to SCREAM at the person three feet away from me to be heard :cool: