performance upgrade

ric · **Posted:** Wed Dec 10, 2014 10:49 am

Jdpber wrote:

but makes the boat sound great.. i am an exhaust man.. i lie to hear engines rumble.. the lap of a cam and the hum of the rpms..

It's fun for about 15 minutes, then it's annoying.

Walt · **Posted:** Thu Dec 11, 2014 6:31 am

Yup,like they said (well, ok... everyone but Rick as usual) Sounds great, is really expensive, and does nothing for performance.... but sounds Awesome! I would certainly not install it on a boat after-market. If you are asking us about an air filter, then an exhaust system that involves hull cuts and re-plumbing your existing exhaust system is probably way beyond your skill level.

atlmover · **Joined:** Mon Jun 09, 2014 10:02 pm **Posts:** 52

I was just curious of price and availability.. Figured a boat dealer might do install.. Just figured there would be more interest from others about modding and improving performance. Can't help it... if you give me 300hp I want 400hp!

ric · **Posted:** Thu Dec 11, 2014 11:29 pm

atlmover wrote:

I was just curious of price and availability.. Figured a boat dealer might do install.. Just figured there would be more interest from others about modding and improving performance. Can't help it... if you give me 300hp I want 400hp!

The thing about boat engines is... they're limited by their HP by major components. They're not like a car where an air filter and muffler gives you a nice boost. Camshafts and intakes is how they limit the HP, everything else is fine. If you have a carb'd boat it's really easy to upgrade, but if you're fuel injected you're pretty much screwed unless you get rid of it for a bigger carb since there's no way to upgrade it's air flow. They don't make aftermarket throttle bodies and intake runners for boats.

Take my boat for example. 220hp carb'd 5.0 vortec. A simple cam and carb/intake manifold swap brings it to 300hp. Swap in a vortec 5.7 which costs a couple hundred bucks, and I can easily be rolling around the river with 400hp with nothing done to the motor except a decent cam and carb. Why haven't I done it? I've considered it. I've priced it all out, but in the end a really good prop gave me what I was looking for.

deafwish · **Posted:** Fri Dec 12, 2014 12:08 am

Another thing to note is that marine engines to not turn the same RPM as automotive variants.
A K&N flame arrester may show an increase on a race boat, pulling 6500RPM, but may show no improvement on a 4800RPM boat.
Boats are designed for low RPM torque, which is why the cam spec's are similar to tow trucks.
Great performing 2BBL carb's are quite normal on SBC powered boats but are a throw away item on a car, as they can't supply the flow for higher RPM!
Quite often our drives are also limited to RPM's...

Walt · **Posted:** Fri Dec 12, 2014 6:35 am

My K&N definitely added some power. That's because it roughly tripled the size of the air filter. Plus, it looks good (See Walt's mod's for pics).

Besides, you can't have the Corsa exhaust thundering across the cove and tell everyone "....it's a Volvo". They just imagine some preppy wearing an Izod shirt and argyle socks.

RotaryRacer · **Posted:** Fri Dec 12, 2014 9:00 am

atlmover wrote:

I was just curious of price and availability.. Figured a boat dealer might do install.. Just figured there would be more interest from others about modding and improving performance. Can't help it... if you give me 300hp I want 400hp!

There is a lot of interest in improving performance on boats, BUT it just isn't "worth" it.

As I mentioned earlier, if your boat is good for 50 mph, you need to add 40 hp to get another 2-3 mph based on the specs direct from Four Winns. To get that much more power is a few b.o.a.t bucks and honestly is that worth 2-3 mph? Not to me and not to many others either.

This is especially true b/c in most cases you can get a prop that will increase your speed by a few mph for $200-400.

Also, you bought a conservative, family boat. It is not and was never meant to be a "go-fast" boat. My guess is, that you can do everything that is reasonably possible, prop, cam, exhaust, intake etc., spend $4000-5000 or more and you MIGHT have a 55-57 mph boat. It might touch 60 but that hull isn't really designed for that speed and at some point the VP SX drive is going to be a limited....power capability and also ability to pick up cooling water for the engine....also drag...the SX is not a high speed drive. Then you will be looking to convert to a Mercruiser setup so you can get a real high speed drive and spend $10,000....then you might get a reliable 60 mph....then something will break and you will be out another $4000-5000 to rebuild/repair....OR you will get a 60 MPH boat that is unctrollable/unsafe b/c the hull can't handle the speed.

Then you will realize that when you use the boat, you normally just have a few friends and family on board and after all the mods the boat is LESS useable b/c it is loud, has a hard time getting on plane with a load and is finicky b/c of all the mods....and you will wish you just had a simple easy to use, reliable 50 mph boat that did everything without much fuss.

Focus on getting the prop tuned to your use and call it a day. Or buy a couple props, one for speed one for grunt and swap depending on the mission of the day.

Walt · **Posted:** Fri Dec 12, 2014 5:11 pm

RotaryRacer wrote:

buy a couple props, one for speed one for grunt and swap depending on the mission of the day.

We have a winner!

I run the HiFive 90% of the time because we are generally loaded and out to wakeboard (with another person in a tube running the camera) or 2 tubes at a time.

Very early and very late in the season I run my 3Bl 19P for that extra 2 MPH, when we only have the core group that goes along, and enjoys the faster runs (albeit for only short periods of time). Also a little more economical at cruise.

Have fun, but ENJOY it. Personally, the only hi dollar mod I would recommend is Perfect Pass.

atlmover · **Joined:** Mon Jun 09, 2014 10:02 pm **Posts:** 52

The Prop is currently at Mark Croxton's prop shop getting repaired and blue printed. It had a high slip so hopefully he can tweak it and gain some performance. I guess I'll buy that k&n spark arrestor too and maybe get 52-55 hopefully. I know its not a go fast boat I just enjoy getting the most out of whatever I have.

ric · **Posted:** Sun Dec 14, 2014 2:59 am

I'm getting 10-12% prop slip. When it comes to props you get what you pay for.

RotaryRacer · **Posted:** Sun Dec 14, 2014 9:54 am

atlmover wrote:

Its a 3/4x19 3 blade SS. Hitting 5400 rpm at 50mph. From a reply on here I was told 5000-5200 was max rpm but it was still pulling. (I didn't know that was the max until after the run). The guy repairing the prop said I had 26% slip rate. He said he would repair and blueprint it and it would really help.

Based on this, I assume the boat has the 1.43:1 gear ratio.

If so, I think it is plausible that with the prop fixed you could get into the 53-54 mph range. Get the slip down to 15% and the revs down to 5000 and you might just hit your target.

Flying Sushi · **Posted:** Mon Dec 22, 2014 8:55 am

We installed Side exhaust Corsa Exhaust System (Quick and Quiet Plus) on our E6 this past winter.
All parts cost came out to be about $1800 but I chosen to let dealer installed them while the boat is in winter storage. Also the best way to install them is to take engine out so I did not feel I wanted to do myself. The total came about $4k but we love the sound… This system was $3950 option from factory so it did not make too much difference in installed them after we took delivery of new boat…
I understood there is no performance difference but the fact with our boat is little different.. We picked up about 3mph on top end and I was very happy to see the difference. When the system is in Quiet mode my wife is almost OK with this loudness so this was a Win Win situation for me…. Happy Boating…

Corsa Marine Application site is
http://www.corsamarine.com/media/pdf/Ma ... -Guide.pdf

Before Exhaust System Installed

After Exhaust System Installed

PS. If you noticed difference in trim position on 2 photo, I re calibrate gauge to work with new Smart Craft Gauge so drive are in same position. Just different indicator position.

www.iFourWinns.com

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