www.iFourWinns.com

I have read many posts that for the most part dismiss engine mods as a way to increase performance. I know that it may not be the most economical way to improve performance but from a technical perspective wouldn't an increase in horsepower and torque (albeit in the proper rpm range) provide an increase in performance.

With all that being said why do boat manufacturers offer a variety of engine packages with a variety pf horsepower ratings? It seems as though typical car performance mods are not easily transfered to marine applicaitons. But wouldnt most performance improvements that increase horsepower (cams, intakes etc..) help with some aspect of boat performance?

Thansk for any insight.

IMO the issue is that most aftermarket engine mods are very expensive, and the increased HP and/or torque are slight. It takes a significant increase to make any appreciable difference in boat performance, which you do get from an upgraded power package; you don't get it from changing to a K&N intake or switching to through-hull exhaust on a small block.

Just my $.02.

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Mike
2005 Four Winns 230/240
VP 5.7GXi/DP
1998 F-150 XLT
Boat Pic

Thanks 230 Mike. It seems as though you get my drift. Cost notwothstanding I beleive you can see performance gains through well planned engine mods. And I further agree with you that it would take something sgnificant in terms of horsepower to realize the improvement.

In my previous post I was trying (poorly) to point out how manufacturers provided different engine packages with increased horsepower outputs tp provide performance gains. For example, a 5.0 and 5.7 Mercruiser provide different hosepower ratings yet for all intents and purposes the exterior dimensions are the same. It would then, seem to reason that there is definetly a correlation to horsepower and performance, and more than likely several ways to get there.

Thanks Imac2 for starting this, I like the potential....

In the example you provided, these are different blocks/displacement engines.... "There's no replacement for displacement". However, simple mods you may try on your car, such as Using a K&N intake tube and box vs factory I have not seen. As far as exhaust, I think a boats is very un-restricted due to the short length, no real mufflers/Cat. I don't think you can "chip" a marine engine either. You could probably re-program the computer to adjust the timing curve, but that could be very expensive for little gain. As far as bigger automotive applications, The heads/cam is the one that comes to mind. These are basically truck heads/cams since they should have good low-end torque (I looked it up on my last boat, anyhow).

I agree marine engines could "breath" better. I know my air cleaner is undersized for my boat, I'm sure the intake is too. However, is it worth spending a couple hundred $$ for something I only spend 40 hours a year in, and hardly ever run WOT? I don't think so.

If anyone comes up with some simple mods, such as a larger air cleaner, or re-locating the air cleaner to get cooler air, please post. Otherwise, I'm happy with my 320 hp.

_________________
Walt B
"Debt-Charged"
Black '07 H210SS
6.2L Bravo One turning a 21P HIFive
Wakeboard Tower with Perfect Pass Stargazer version
Missouri River; Kansas City, Mo.

Excellent point. the 260 hp from my Volvo 5.0 seems sufficent for most of what I do. I have also considered mods for reliability, smoothness, efficency and economy. I am currently consdiering ignition upgraades. Mallory or Accel offer marine grade products that I may consider this spring. If , as you say, that the exhaust restriction is minimal then most improvements to the top end should yield results. Again in the interest of reliability I would consider new marine parts form Holley etc... I think we may all be a little surpised what can be accomplished for a moderate investment.

Best of luck, but remember: it's all been tried, countless times. These aren't cars.

_________________


Mike
2005 Four Winns 230/240
VP 5.7GXi/DP
1998 F-150 XLT
Boat Pic

Ah, not exactly what I had in mind when reading the thread. Please let us all know what you end up with, and results both in performance and cost/economy. This is not an easy subject to document, compared to say improvements in a quarter mile time when refereing to automotive upgrades. The only mod along those lines I plan on doing would be installing multi-electrode plugs when I replace them in a few years.

Since we aren't really a "go-fast" crowd here, we don't have too much info on the subject, but perhaps searching other forums would yield more tangible information. If you search and come across such, please do share.

Imac, From reading a few of your posts I take it you have a 210 with the 5.0L? IMO, just a tad under-powered, depending of course on the use and prop. I have documented in other threads how happy I am with the performance of my power package, but would always be interested in comparing potential gains for the $$.

_________________
Walt B
"Debt-Charged"
Black '07 H210SS
6.2L Bravo One turning a 21P HIFive
Wakeboard Tower with Perfect Pass Stargazer version
Missouri River; Kansas City, Mo.

There may not seem to be much restriction in the exhaust, but Volvo saw fit to have two transom types on the prefacelift SX/ DPS drives; the std and the one they called MHP (minimum hydrstatic pressure). The former has the stub type exhaust tube, rather than the type joined to both the drive and transom. There are other differences, primarily the anode type and the top and lower swivel assemblies. I think it's just more noisy rather than making any appreciable difference to exhaust back pressure, maybe it actually does something positive on the big blocks.

The design of the exhaust manifolds is pretty crude as far as airflow is concened. Nothing like a tuned tubular manifold on a car, where the lenght of each pipe is calculated to make exhaus gas exit as easy as possible.

Supercharging for increased low speed torque?

Graham

I did run across this when parusing chips/upgrades to the 6.2. Has anyone tried this or similar.

http://cgi.ebay.com/ebaymotors/DYNO-BOOST-PERFORMANCE-CHIP-Mercruiser-6-2-MPI-340-SKI_W0QQcmdZViewItemQQhashZitem2557b9a123QQitemZ160385573155QQptZBoatQ5fPartsQ5fAccessoriesQ5fGear

If it delivers as advertised, the price would be in-line with comparable HP improvements. Again, I'm still researching a larger aircleaner for mine. No luck with K&N. I may hafta mod an adapter to my intake that fits one of thier sizes. My present aircleaner is only about 4" in dia. I'm suprised it doesn't get sucked in at WOT!

_________________
Walt B
"Debt-Charged"
Black '07 H210SS
6.2L Bravo One turning a 21P HIFive
Wakeboard Tower with Perfect Pass Stargazer version
Missouri River; Kansas City, Mo.

In a previous life I had a 1988 SeaDoo SP PWC. Out of the box it did about 35 MPH. I modified it in just about every way I could think of and eventually got it to peak out at about 51 MPH. With all of the mods, reliability suffered. It was a lot of fun, but think I spent more time working on it than I did riding it. I eventually sold it and bought an SPX that could do 50 MPH out of the box, and kept it stock. Once I found that I was putting less than 30 hours a season on that one, I sold it. What can I say? Clearly I was obsessed with modifying that first PWC. If you do look to modifications for some performance improvement, just make certain you are not sacrificing reliability.

BTW - the last mod I made was adding NO2. NO2 is quite a thrill, huge temporary perfomance boost at the push of a button. Wish it was the first mod I made - I might have stopped there!

_________________
2007 Horizon 200
4.3L GXi/ SX 225 HP

Jim,

I think you meant N20, nitrous oxide. If you did use NO2, the clouds of acrid brown smoke following your PWC would have been something to see!

Graham

Actually I meant NOS, for Nitrous Oxide Systems, the place where I bought the 'fogger' style kit I used. Fortunately, they do not seem to offer a kit for the Volvo 4.3L V6 my 200 has!

_________________
2007 Horizon 200
4.3L GXi/ SX 225 HP

Sorry Jim,

I suspected that is what you meant, but I'm a chemist by training. I remember dissolving copper coins in concentrated nitric acid at school; the copious amounts of brown, acrid NO2 given off was pretty impressive; not the most useful bit of chemistry I have come across, but impressive to a 12 year old a long time ago !

I also remember a Honda with N20 ( NOS) I had a ride in once; vicious acceleration,, but I would worry about how long the engine would last.

Graham

Yeah, I don't think the NOS would be much of a benefit.... except tubing or, perhaps putting the boat on the trailer quicker

_________________
Walt B
"Debt-Charged"
Black '07 H210SS
6.2L Bravo One turning a 21P HIFive
Wakeboard Tower with Perfect Pass Stargazer version
Missouri River; Kansas City, Mo.

Are you sure it is an air cleaner, or not just a spark arrestor? I personally have never seen anything but spark/flame arrestors on a boat, no air cleaners. My guess is, how much dust is out on the water?
I have always wanted to add an air cleaner to my boats/jet skis, but have not spent much time or money looking for any.

lmac2,

I will throw my two cents in, IMHO, you would be better off saving your performance upgrade money and putting towards a High performance PWC. They do close to 70 mph out of the box now days, and keep the boat reliable and dependable.
As you can see in my sig photo I have 3 jet skis to tag along to camp behind our slow boat! But that slow boat sure is nice to camp on!
The one thing you can not change with your current boat, no matter how much HP you increase, is the hull design. Sure you can drop in a 8.1L supercharged with NOS and prop it correctly, but will the hull handle the speed?
If you want a go fast boat, you would be better off with a Baja vs a FW. JMHO

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2000 248 5.7L DP
'92, '94 SXI 750, '08 STX 15F, '12 Ultra LX 300
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