BigChris

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

Knot 4 Me

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.

Sydwayz

iTrader: (1)

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.

BUP

iTrader: (9)

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 ?

BigChris

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.

SB

iTrader: (1)

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.

Knot 4 Me

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

BigChris

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.

Knot 4 Me

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.

BUP

iTrader: (9)

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.