Silent Choice/Captains Call Side Exit
 

I have a family bowrider, I know it's not a powerboat, but the crew over at iboats aren't the performance gurus if you catch my drift. And I'm thinking there might be more guys on this forum who've got the advice I'm looking for. She's a 2007 Four Winns Horizon 220, but she's got a fairly rowdy 383 Gen 1 SBC in her.

Video of idle:
Here's the thread on my engine build.
http://forums.iboats.com/forum/engin...m-from-6-2l-v8

Corsa System together, its the latest generation, with the black 3 wire connector. see this link:
https://greatlakesskipper.com/four-w...t-diverter-kit

I'm also putting these mufflers inline:
Full Time Inline Silencers - 4" - CP Performance

So before I go cut holes in my hull. I'd like to ask guys who have experience with side exit exhausts a couple of questions:

We spend some time in the Chesapeake, I see lots of side exit exhausts, and at least in what I've seen, it's common for the exhaust tip to be very close to the water line when the boat is not on plane. What are the reasons for this? (besides having the exhaust "run" downhill after the diverter to drain water) As long as I can maintain a downhill run, is there a disadvantage to mounting the side exit tip a little higher on the hull?

What are some of the common pitfalls to avoid, that others have learned of experienced?

Suggestions for marking the location on the outside of the hull from the inside? Was thinking a laser pointer, shining through the hull any ideas?

I'd like to do a side exit and have the location roughly here on the pic (water line when not on plane is right at the black stripe on the hull)
http://i1376.photobucket.com/albums/...psd7cb4lx5.jpg

My side exit is above the waterline at rest even with a big block. I'd say by your desired location it is a bit too high. There is no concern with the exit being at or near the waterline if you have the stainless butterfly flappers in the exits. My "mufflers" are actually baffles in the Corsa elbows that direct the exhaust to the sides. After owning boats with side exit and rear exit I would never again own a side exit exhaust boat (unless it was a cool old race boat!). The don't sound as good and if you have seating near the exit your passengers will quickly grow tired of the noise. If there is room I'd route it out the back.

What makes you think you want side exhaust? It's going to be loud

You can likely use a bright flashlight with a cardboard template of the hole, taped where you want it to be on the side of that boat. Tape the template with the hole punched out of it to the side of the boat. When dark, or inside of a closed/dark garage, have a partner aim the flashlight directly at the hole in the template, while you crawl in the bilge to locate the silhouette of the hole within the gunwale.

Many current within the last 13 years to new --- family rec boats have to use side exit thru hull exhaust. They way the transoms are constructed and with the addition of built in extended swim platforms that the I/O family rec boat market has built into the hull, mainly is reasons.
plus not as load behind the boat for skiers and tubers.

what exhaust and manifolds do you have for this.

I see a Volvo outdrive and Volvo never made a stock production 383 - you either had a 5.7 bored and stroked or you bought a 383 repower package of some sort. Let me guess is this possible Michigan Motors 363 repower.

Is this a MPI engine ?

your gear ratio could be off for the repower ??? but I am guessing cause I have no idea what you have.

Not sounding like a bad guy here but your engine idle really does not sound that good especially if you have stock Volvo manifolds - they do not use flapper valves aka water shutters and your idle sounds like a possible water reverter. plus the semi low draft stern of Four wins can add to reverting water.

I would post your cam specs if you know them.

Is this a NA only engine as well ?

Sometimes the microphone on a iphone isn't the greatest. This wasn't really an engine build thread. More of a what shouldn't I do thread. But I'll entertain.
Full time, I'm a mechanical engineer who's spent the last 17 years working in new product development. I am one of the inventors listed on this patent. US Patent # 20160015167
As a side endeavor this is me RPERacing. I own a small Stuska waterbrake dyno, and a SF60 flowbench, and a nice Bridgeport with DROs. I build competition dirt oval karting engines, and I'm pretty good at it.

I built this engine, back in 2011, and had an Eagle cast crank failure last spring (May 2016), so she came back out. (crank broke in two)
She's a naturally aspirated, iron headed SBC, 12558062 casting number vortec heads.
9.8:1 comp ratio
Eagle forged crank, (balanced rotating assembly by Chris Fritz local crank guy) I stuck with Eagle b/c the gave me a very attractive deal on a forged unit after speaking with their warranty folks.
. 003" piston to cylinder wall with hypereutectic,
.030" top ring gap, .035" second ring gap,
Valve train is sprung to handle 6500 rpm, though it'll never see it.
Cam is Comp Cams 08-466-8 (218° Intake, 224° Exhaust @ .050", Installed at 109° ILC, 113° LSA) I was told by the folks at Comp Cams this was about as far as I could go without reversion issues (with stock exhaust) and an idle south of 800rpm.
Summit brand, chinese roller rockers 1.5:1
Edlebrock performer rpm manifold
Edlebrock 1410 750cfm carb (.116 primaries, with .073 by .042 metering rods, pink springs, .113 secondaries, .033" accelerator pump nozzle) pulls nice on holeshot.
MSD dizzy 15° timing at idle (750 rpm idle), custom made timing advance limiter (14.5° advance) total advance is 29.5°, all in by 2000rpm
Factory stock volvo cast iron exhaust manifolds and risers.

Boat used to be a 5.0L, previous owner let the engine freeze at 125 hrs, I bought her knowing this and the selling price reflected that. She now has 285hrs, so approx 160 hrs on the 383.
Boat also used to be an MEFI 4 system, that AZ speed and marine reflashed but that's an episode I rather forget. I modified a used ebay wiring harness to connect the new engine to the boats wiring harness so I could convert it to carb and mechanical distributor.

She's a 60 mph boat at 5100 rpm. She gets up and fly's nice, but unlike some of the rigs you fellows must have, cant tolerate any sort of wake at that speed.

At the end of the day, she's a family bowrider. However, take her off the bay, and put her in a freshwater inland lake, and pretty much the only boats faster are the bass boat crew, there are exceptions to this but they are few and far between..

This model came with captains call as a factory option, the factory location was low near the surface of the water when not on plane.

So back to my question:

I'd like to mount the side exit tips a little higher, in the pic on the first post, you can see there is a step in the hull, I'm forced to be either above it or below it. Factory was below it with the bottom of the exhaust tip right at water line when not on plane. I'd like to be above that line, and as long as I maintain a downward slope to the exhaust run, is there a disadvantage?

What other pitfalls should I watch out for during this little project?

I also realize the point of this project is really the exhaust note/tone and not really a performance gain, thus the selectable diverters so that I cant go back to stealth mode when appropriate.

My own real life opinion - I can't stand the exhaust note from side exit exhausts. It separates the pulses too much. Maybe mufflers will stop that a bit.

Nope, still sounds like crap with baffles/mufflers. Assuming your downward angle is sufficient, the only pitfalls are aesthetics and passenger comfort.

What is a sufficient downward angle? The guys over at iBoats are saying 6° minimum.
Roughly 5° is 1 inch drop in a 12 inch run. My overall run is shy of 4 ft. So I was thinking about 3.5 inches drop from the diverter to the tip.

I noticed greatlakesskipper took the listing down, so the link no longer works. But these diverters have a 1.5 inch hose that connects the port and starboard side. I noticed that was unique and thought to myself "now why is that?"

I'm betting this is to improve sound quality. I'll post a pic when they arrive.

Yes, I've seen crossover tubes on some Volvo setups. I too assumed it acts like an X-pipe on car exhaust. I can snap a pic of my setup and try to take some measurements of how much angle my exhaust tubes have.

the crossover for Volvo doing silent choice is 100 percent needed and there is a Volvo Service Bulletin all about. A short jist is -- it helps equalize the exhaust pulses and in return helps against water reversion. Out the side exhaust sounds like an engine running on half its bank.

Have done over 60 Volvo s in the past 16 years from 2001 to brand new boats 5.0 to 8.1 -- carb apps to MPI - Silent Choice installs. A lot had to be out the side exhaust with the family Rec boats.

pic of diverters
http://i1376.photobucket.com/albums/...psrbr6uw45.jpg

corsa and Volvo worked together on that design above. and also a few different things for the Volvo CAT engines. I was there in person when all of that was being installed with Volvo and Corsa for an engine on a engine stand.

BUP

Interesting. Just out of curiosity what's the design difference that makes the volvo setup want this while the merc setup doesnt.

After 60 installs, got any good advice for the least messy way to cut through the hull without risking chipping the gel coat?

if you can find another route, do not do side exhaust. I had a 27 nova. twin 350's side exhaust. rocking side to side tied to the dock both engines ingested water. sold it to a buddy. he cut thru hulls above platform and just let the exhaust water run off the platform. wasn't all that aesthetically pleasing, but worked way better than wellcraft's idea... cutting exhaust holes. the correct size holesaw. measure your tips. if 4-1/8ths, use 4-1/4. 4 inch even, 4-1/8.

Thanks for the heads up, but she's a trailer princess.
When we're done on the water, she goes back into my detached garage/shop.

This was the reason I was looking to mount the tips a little higher on the hull. But it begs the question- whats more important more of a downhill slope to the exhaust route or just higher on the hull.

Also with the diverters closed (as default would be with the ignition off (switch will only have power when ignition is in the "on" position) wouldn't it provide a descent amount of resistance to water ingress?

extension blocks for the risers possible , you need to measure your waterline distance to the riser to figure all that at your from how you load your boat with everything including fuel AND PEOPLE hanging on the swim platform creating the stern deeper in the water. This is common to have water enter thru the exhaust. too much weight on the extended swim platform parting at rest and wave slaps up against the hull. just one example.

Next. . All connections of hoses especially from the riser need to be straight - any off angle hose / boot restricts water flow and creates a hot spot internally of the rubber hose - this in return blisters and burns a hole thru the rubber boot creating a huge water leak inside the engine compartment. Anyways good luck with it.

I was about to do a silent choice even with all new manifolds and risers, the boat came in last week and what I always check first before anything is ----- found the lower transom soft. So all of that has to get fixed first before anything. Make sure all is solid before doing anything. Just saying

Side exhaust sounds good IF you have a crossover / H pipe. My boat has side exhaust that sits right in the waterline. You see alot of Chaparrals, Cobalts, etc. Set up with the exhaust in the water at rest. Being a seasoned veteran of side exhaust, I would want slope/drop over tip placement. All or most of the Corsa side tips will have a flapper valve installed. I personally would be surprised if you had an issue with reversion, that cam has has very little overlap and internal flappers in your tips will (and like Bup stated, the crossover tube) minimize any reversion with your set up.

I had a 1989 23 Velocity/Regal with a 454 mag. It also had side exhaust and IMO it sounded fantastic. It originally had stock Mercruiser exhaust with mufflers. I put on Lightning headers and removed the mufflers. Great boat, we had a lot of fun with that boat.

Most Corsa side tips are oval in shape and the hole you will cut in the hull will be oval as well. I would guess the tips would come with a template from Corsa. The Corsa tips also have stainless butterfly flappers in them with silicon boots. My tops sit right above the waterline. I've never had water enter up thru the tips. I have had water enter up thru the y-pipe.

I've always wanted to add a crossover to my setup but figured I'd leave it alone until a flapper broke in the diverters. After 12 seasons everything still works fine including the solenoids so I've never messed with it. Would be interesting to hear how it alters the sound. Most of the side exhaust boats on our little pond are small blocks. I'm pretty much the only big block boat with it and everyone says my boat sounds way different than the other boats and they can tell when it is me headed their way.

After years of training, my 11yr old son can tell the audible difference between a BBC and a SBC.

He's funny and corrects his grandfather when we're on the bay and says "no pops, that's twin big blocks, just listen you can hear the difference" ( when this first happened, I smiled to myself and thought "that's my boy")

On a side note, besides the power advantage, this is what's sorta cool about a 383, it's no big block, but it doesn't sound like your garden variety SBC.

Happy Independance Day, and I hope you enjoy your time on the water.

I'll post some pics of the project as I progress. I am in the process of waiting for the UPS man to bring me all my goodies.

So some of my parts arrived, not at all stoked with the craftsmanship of the diverters.
This hole is factory and was cutout with a plasma cutter.
The attention to detail doesn't present itself a performance part.
On the outside they are pretty. On the inside, not so much.,


http://i1376.photobucket.com/albums/...psauheuebz.jpg
http://i1376.photobucket.com/albums/...psks4fw7sk.jpg

I have had with and without the crossover and it really evens out the sound and makes the boat sound like a V8 no matter where you are around the boat, in or out. My set-up without the crossover had a couple of 12" Borla mufflers (which I still use) and it did not sound nearly as good. Another issue I had without the crossover was when I would go into a sharp banking turn, the water would accumulate on the high side and it would really cough and sputter...with the H placed in the elbow where it makes the turn for the side exit, the water is simply expelled thru the H and out the low side. I promise you will love the change. It also seemed like it knocks the loudness down a few Db's . Just find a guy around you that fabs up turbos/piping and it will be an easy job for him. Just make sure there is a hose size for what you will be stubbing on. I think mine was 3", but when I read up on it, IIRC, smaller is just as or nearly as effective. Its also good to read here that the H pipe can help diminish the effects exhaust/water reversion!

So finally set aside some time to work on this. My 11yr old son showed great interest in this project and helped. Not the usual handing me tools, but he's now graduated to loosening/removing components and easy installs. I check his work. But it was a great father/son experience and an opportunity to spend some quality time with him. We had a goal and got to see the results of our work.

Couple things I'd like to share:
For locating the hole location, I used 2 penny sized rare earth magnets which I could fix one on the inside of the hull and one on the outside they were strong enough to "stick" together with the hull in between. This helped in lining up the location from the inside of the hull to the outside.
For cutting through the hull I used a "rotozip" tool used for drywall. The glass was hard on the bits, I used 2 bits, one for each side. This made a nice controlled way to cut out the shape. My son held our shop vac nozzle right at the point I was cutting and made the whole operation virtually dust/mess/itch free.

Anyway here's what I've got:
Two diverters as pictured above with crossover tube.
Two inline mufflers
The side exit tips
Corsa wiring harness

We finished up last night about 8:30 ish and tonight we'll test run her off the hose and take her to the lake for a trial run if the t-storms hold off.
I'll post a you tube video. I am curious/excited to try it out.
http://i1376.photobucket.com/albums/...pspvvo8ssn.jpg
http://i1376.photobucket.com/albums/...psdihfes35.jpg
http://i1376.photobucket.com/albums/...psjbksbhcs.jpg

Nice work.
FWIW, the "tile bits" for the Rotary Tools work better for fiberglass.

Excellent job! I think your tip location is perfect. For reference, this is how much fall I have from diverter to tip. And tip location.

Thanks everyone for your tips, advice and kind words.
Here's a really short video

It thunder-stormed today right at 5 o'clock. My son and I pulled her out of the garage and gave her a good scrub down.
The dew point was 74°F and the relative humidity was 98% when we shot this. So for those of you wondering, it's not smoke, it's visible water vapor because the humidity was ..... well lets just say "it's the air you can wear" .

Sounds nice.......... and we're only hearing half the sound!

It sounds great, especially for a small block! It would not sound that good without the crossover tube.

Thanks for the comments guys,
Make no mistake, I've spent alot of time dialing this engine in. Countless timing and jetting test runs on the lake after work.

I was a little concerned after some of the comments BUP made regarding the tone sounding like a 4 cylinder. (because in my head I knew what he was saying made total sense) So when we first fired her up, I walked all around the boat and just listened. I totally agree with liquidlounge regarding the crossover tube and I will say this: the cadence of a V8 can be heard no matter where you are standing.

Does it sound like twin 502s, no of course not. That's not what this is.

But for those in the know, an experienced ear can pick out the difference between a 383 and a 350. The 383 just has a different tone.

And I really like the mufflers. They knock down the "shrill" sound that I've heard on other boats. They make for a more throaty-bassy sound, which is what I was after. Where sophisticated meets rowdy.

Full Time Inline Silencers - 4" - CP Performance