A quest for speed...

[SS194]

I'm a speed junkie. I'm always looking for ways to go faster. But what I really enjoy is doing the little things that add efficiency. Removing weight, drag, good tuning, stuff like that. Anybody with money can install a blower and go fast. I like to be smart about it and do it for less money (because less money is all I have)

Anyway, I have a 2001 Larson SEI 190. 18.5' bow rider with a Volvo Penta 4.3. Coming for a guy who loves V8's, I absolutely love this engine! Great fuel efficiency, tons of low end tq, and a great top end. On smooth water, me and my fiance' (112 lbs), I can hit 50 MPH exactly per the GPS. The other day on rough water, 3 of us, and a bunch of junk, 47. I don't know if it's fast for a V6 bowrider, but I wasn't expecting 50 MPH.

Well, I want to go faster. For now, I have on order Smart Tabs. From what I've read, people get up to 3 MPH with them along with the other benefits. Then what about a stainless prop? I've got a beat up cheap aluminum prop right now. That's got to be good for another MPH or two. Then my winter project will be to install a 4bbl performance carb. I've heard from people with experience that it's the best bang for the bug. Easily 25-35 hp. That must be good for, what 3-5 MPH?

I know there are many who say, forget it, you're wasting your time and money. Well, that may be, but it's what makes me happy.

I really use the boat mostly for cruising around at 30 or less with 4 or 5 people on board. So, I figure as long as I stay out of the secondaries, I'll still keep my fuel efficiency.

Smart tabs......$100
SS Prop .........$250 ish
4bbl carb........$500 ish

So for about $850 or so, I should be able to pick up more drivability, efficiency, lower end tq, and possibly 5-10 MPH.

What do you guys think?
Steve

 

[tashasdaddy]

Re: A quest for speed...

we just went to 4 bbl holley on the 5.7, made a difference getting out of the hole. and smart tabs are the best bang for the buck there is on a boat.

 

[marine4003]

Re: A quest for speed...

Dont you have trim/tilt..tabs bring the bow down,increasing drag..at higher speeds they retract,but still are causing drag, what you want to do at higher speeds is get the bow up, using the trim, bring your outdrive/outboard UP thereby having less hull in the water=less drag. Carb increase..well it'll get you a tad more throttle response,and alot worse fuel consumption, Prop..definitely, find a good prop shop, most will allow you to experiment with different sizes till you find the one that gives you top performance,just make sure to buy it from them and not e-bay. after the prop + carb, running your exhaust thru hull is the next item you'll want in your quest for speed.

 

[LIQUID PROZAC]

Re: A quest for speed...

slow down you might miss somethin' jk it's cool to go fast and feel your cheeks flappin'

 

[45Auto]

Re: A quest for speed...

The 4bbl marine carb will be in the $500 range as you said. Don't forget to add in a manifold, unless your 2bbl is currently running on an adapter.

Don't expect anything at all if you go to thru-hulls. Do some searching on the documented performance differences they have made for people. They'll definitely be louder, but that's all.

If your boat is already maxxing out at the correct RPM range (4800 RPM or so) don't expect much from a prop change. Don't know what your money situation is, but unless you just like buying props, you may want to wait until after the carb change then prop it correctly.

 

[RickJ6956]

Re: A quest for speed...

One of the mods a friend of mine did along with the 4bbl carb was install heavier valve lifter springs. It supposedly bought him 15 - 20 more HP. I never got an explanation why that worked (I'm not a motorhead), but he swore it did.

 

[SS194]

Re: A quest for speed...

A thru hull is out of the question. An open exhaust V6 is not going to sound good.

The carb and manifold should both be about $500, right? As for fuel efficiency, as long as I stay out of the secondaries, it shouldn't change a whole lot, right?

Tashasdaddy, have you had a chance to see how your fuel economy has changed? Did it make a difference in top speed?

The tach doesn't work on my boat right now. I'm going to temporarily wire up an after market tach to see what RPM range I'm in. Hopefully I'm well within limits so I can wait till I get the 4bbl on to make a prop change.

Thanks,
Steve

 

[mddubya]

Re: A quest for speed...

Having grown up on boats my whole life, and listening to my Dad, I think you are being overly optimistic about your mph gains. I've heard my Dad say a million times, that you pay through the nose for everything over 40mph. Yes you'll get small incremental gains, but I'm afraid you're going to be disappointed as to how little you're going to gain with your $500.00 carb.

Best of luck to you though, I hope it all works out like you're hoping.

 

[SS194]

Re: A quest for speed...

I don't know, I've talked to people on the engine forums who say it's almost a must. Makes an easy 25-35 extra hp and makes the biggest difference getting out of the hole. This is from personal experience.

I just read a power boating magazine. They took a 22 ft Scarab and put an aftermarket exhaust on. Average hp increase was about 35 hp I believe. Because of the extra power, they had to swing a larger prop. They gained 9 mph. From 60 to 69 MPH.

So, if I get 25 hp, that should be good for about 6 MPH with a proper prop.

Or does it not work like that?

Steve

 

[Mischief Managed]

Re: A quest for speed...

If you can squeeze and extra 30 HP out of the engine, you should see 53.8 MPH with the same prop efficiency you have now. An SS prop could add another MPH or two. I seriously doubt smart tabs will affect the top speed much. With 30 extra HP, fuel consumption at WOT will increase by about 2 to 2.5 GPH. The smaller primaries of the 4 bbl combined with the steeper pitched, SS prop might actaully give slightly better cruising economy, but it would be measured in tenths of an MPG at best. Good luck! Sounds like a fun project.

 

[IVAZ]

Re: A quest for speed...

The 4bbl upgrade will be the most noticeable. We made that upgrade on an old s-10 we use at my uncles property. It made the little truck feel like it had a much bigger engine. We went with an Edelbrock carb and intake.
The hole shot will be much better and you should see a slight increase in top speed. An increase of an extra 10mph won?t happen with the mods you want to make.

 

[SS194]

Re: A quest for speed...

Good to know. I went with the smart tabs for the benefits other than just top speed, which they claim to give 1-2 MPH. Even if they don't add anything, a 55 MPH top speed seems fairly respectable.

I'd be happy.

Thanks guys,
Steve

 

[45Auto]

Re: A quest for speed...

Been a while since I messed with carbs, but I'm pretty sure a new MARINE carb will still run you between $400 - $500 plus shipping. Make sure you use a marine carb, here's a link with a pretty good explanation of the major differences:

http://www.cpperformance.com/products/Fuel_Systems/carb-selection.htm

Check the magazine you read the exhaust article in and see if there are any advertisements by the manufacturer of that exhaust system. Magazines tend to try to keep the advertiser's happy, the VAST majority of their money comes from advertising, NOT from readers buying the magazine. Here's a quote straight from Corsa's (boat exhaust manufacturer) FAQ:

3. What kind of performance gain can I expect from a CORSA system?

Performance gains vary from boat to boat. Typically the top speed will increase by about 2-3 MPH, which means about a 20 to 30 HP gain. Boats with smaller engines (under 350 cu. In.) will not see much improvement in top speed.

http://www.corsaperf.com/mfaq.htm

You'll have to decide how many thousands of dollars a few MPH is worth to you, but I found that the most cost effective way to get speed on the water was to get the biggest engine I could in the boat I wanted. The gas mileage difference at part throtttle and cruising speeds is negligible, but the performance difference is incredible if you want to pay for hammering the throttle. You'll find that the torque spread of an engine, as opposed to peak HP, makes a huge difference on the water. Hot-rodding a boat is probably closer to trying to hot-rod a loaded semi-trailer than a car. It might be beneficial to consider putting your money towards a V8.

 

[SS194]

Re: A quest for speed...

That makes sense. I was really shocked when they saw a 9 mph increase in top speed.

Well, like I said, I'd be happy with spending no more than $1000 and gaining maybe 5 mph. Plus the low end tq would make it "feel" faster. Tq is a good thing.

What are the top speeds of most bow rider boats? Say in the less than 22 ft range? Think 50 or so is an average?

Steve

 

[IVAZ]

Re: A quest for speed...

Here is a couple of threads you might enjoy reading.

Here is a thread where someone upgraded to a 4bbl carb, intake, new cam and vortec heads. Your engine should already have the vortec heads. This guys top speed increased dramatically.
http://forums.iboats.com/showthread.php?t=335053&highlight=4.3+4bbl+upgrade

This thread is on different 4.3's top speed. Some are very fast IMO.
http://forums.iboats.com/showthread.php?t=276549

 

[45Auto]

Re: A quest for speed...

50's are a good average for bowriders less than 22'. Go to Boattest.com, give them an email address, and you can look at their actual tests of lots of boats. It's free, you don't need the archive tests they want you to pay for. One of the categories is Bowriders, 16'-20' or 20'-25'.

http://www.boattest.com/

Stingray boats also has a nice performance page with lots of different types of boat speeds to compare:

http://www.stingrayboats.com/produc...d=1&sort=&showstingray=&onetokeep=&tocompare=

You can change the lengths and HP variables and see the different boats.

 

[Willyclay]

Re: A quest for speed...

Our son has a 1995 Ebbtide 192SE bowrider with 4.3LX Mercruiser GenII with OEM 4BRL carb. It is listed as 2,600lbs. empty and tops out at 49MPH with the factory aluminum 19P prop. You apparently have a very nice running package. Good luck with your project and keep us posted on what you do!

 

[SS194]

Re: A quest for speed...

Thanks, first things first, I'm going to install the smart tabs and see if they do anything for top speed. I ordered the retractor bracket so I can retract them, do a WOT pass, then lower them and do another and see what the difference is right then and there.

I'll start saving for a carb and manifold and SS prop, but I have a feeling it'll have to wait until next season. From what others have said, it makes a huge difference. I'm pretty excited!

Steve

 

[xxturbowesxx]

Re: A quest for speed...

Wanna go fast? Sell your boat and buy a high performance boat. Usually on boats not designed for high speed your hull will be the limiting factor because you will be pushing alot of water. An example was I used to have a 18' procraft bass boat with a 200hp and it would run 65mph. I had the quest for speed and bought a action marine 18' with a different hull design and with the same motor it would run 85mph. Just be happy you can run 50mph and enjoy your boat.

 

[SS194]

Re: A quest for speed...

I'm not exactly saying I want to go 100 MPH with this boat.

I like this boat, got it for a great deal. I also am impressed with the engine.

Some simple mods to free up a little power isn't worth selling the boat over and getting one that's made only for going fast. If I had the money, I'd have two boats.

Steve