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Go Back   WakeWorld > >> Boats, Accessories & Tow Vehicles Archive > Archive through June 10, 2005

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Old    warren            05-28-2005, 7:22 PM Reply   
I have a 1994 Mastercraft Maristar with a 350 cu. in. tbi (275 hp). Engine rpm's at WOT are 4250 w/ 14 x 18 OJ prop w/ top speed of 42-43 - no ballast, calm waters, cool day, 2 people in the boat. We have not added any ballast to the boat yet, but will probably be doing that this year. With 8 people in the boat, and no ballast it still has decent hole shot.
My question is, to improve performance I could go to a lower pitch prop, (which may or may not lower top speed), or I could put some money into increasing H.P. Does anybody have any suggestions on a performance package (heads, cam, intake) for the Indmar 350, and will the tbi fuel injection compensate for the added H.P.? Can I increase the fuel pressure to the existing system to compensate?
Also any imput on increasing fresh air intake to the engine compartment? Exhaust mod's?
Old    Big D (bigdtx)      Join Date: Feb 2005       05-29-2005, 5:56 AM Reply   
Unless you want to drop big bucks I'd look at an MSD ignition and a K&N flame arrestor. Or you can ask over here:

http://www2.hotboat.com/forums/forumdisplay.php?f=9
Old    warren            05-29-2005, 12:35 PM Reply   
Big D
Thanks for the link, I'll check it out. As for the big bucks, the boats in beautiful condition and so well made that I feel that it's worth putting some money into. Besides, it's alot of fun! I'm interested in any other info anyone has!
Old    Alessandro Garabaghi (pimp131)      Join Date: Aug 2003       05-29-2005, 2:01 PM Reply   
i have the same engine in my 1994 prostar 205, and we have had the boat saced out (fatseat + 350sac up front) with 10 people in it, and it still got on plane. But when we added 11, it wouldnt get on plane any more. I think you will find that you run out of room before you will run out of hp. The wake can be made really nice with fatseat 2 side sacs (on each side of motor) and a 500lb up front and 3 people
Old    zboomer            05-29-2005, 3:18 PM Reply   
Holy overload... how do you fit 10 or 11 in a Prostar 205? Lay on top of each other?

10 people, fat seat, and front sac? Coast Guard would love you, lol. Isn't that about 3x the USCG rating?
Old    warren            05-29-2005, 5:32 PM Reply   
Alessandro
You can never have too much H.P. can you? They asked me why I wanted more at M.C. My answer is, why have they put more H.P. in their new boats? why offer the LS-1, Corvette engine, etc. etc.? Besides, with all those people in the boat, you need more H.P. to get you on plane and keep you from sinking! Surely there's some H.P. lovers out there!

P.S. I also ride a 350 V-8 Boss Hoss Motorcycle! Love them ponies!
Old    Mikeski (mikeski)      Join Date: Aug 2003       05-29-2005, 8:41 PM Reply   
Don't waste your money on little bolt on things, you won't notice the difference. If it's a ford you can bolt on about 40+ hp with GT-40 heads, same with chevy vortec heads. That's all I would spend my hard earned dollars on.
Old    Tom Barnard (tlb)      Join Date: Feb 2003       05-29-2005, 9:10 PM Reply   
Change the prop, that will make the most noticable difference.


(Message edited by tlb on May 29, 2005)
Old    cdm (cdm)      Join Date: Aug 2003       05-29-2005, 9:29 PM Reply   
i agree, contact ACME
Old    warren            05-29-2005, 10:38 PM Reply   
Mikeski,
I appreciate the post. It's the first answer that is at least headed in the right direction. No offense to the others, but please re-read the question. I already know what changing the prop will do. What will make the most "noticable difference" depends on the difference that your looking for. Anybody have any experience with these Throttle body injection systems? Help!
Old    waterdog2            05-30-2005, 4:23 PM Reply   
If your serious, I would find the HP/TORQUE curve chart for your engine and compare it to the packages on the edlebrock web site, Or just hire a pro.
Old    warren            05-30-2005, 5:46 PM Reply   
Both are good ideas! I emailed Indmar for some info on my package - waiting for response. I plan on taking it to a pro to do the work, I'm just trying to educate myself on the differences with marine, (spec. Indmar), and what I can expect to run into that might end up raising costs,ie. having to replace the fuel injection system, etc. I don't like surprises. It's all information that a Pro would need anyway to determine his course of action or recommendations. Anybody by chance know what type of heads came on these motors? roller cams, or not? cam profiles?

Thanks again!
Old    Jeff Randol (jrandol)      Join Date: Mar 2004       05-30-2005, 6:41 PM Reply   
Has anyone ever put a supercharger on a marine application? Have been thinking about this on a 351 PCM motor. Any info?
Old    warren            05-30-2005, 11:41 PM Reply   
Jeff:
I found a Hot Rod shop that also works on boats, I'll be talking to them tomorrow. I'll see what they say.
Old    Karl De Looff (boarditup)      Join Date: Jan 2004       05-31-2005, 6:40 AM Reply   
In order of cost effectiveness:

1. Prop
2. K&N Flame arrestor
3. Induction
4. Heads and cam

Remember that you are looking for torque. That is very different than what most speed shops are looking for. You also need to have high, sustained RPMs in mind. That means different rollers and springs than automotive - more like off road truck racing than drag or track.

It may be more economical to drop in a new motor than it is to tweak the old one.
Old    Bob (bob)      Join Date: Feb 2001       05-31-2005, 12:11 PM Reply   
Dont let them give you back a boat that only has horsepower above 3500-3800 rpm. Make sure they know you need horsepower down low also. If they are a high performance shop they are accustomed to top end, go fast horsepower. Sounds to me like your best spent money will be a prop change. Dont expect to get something for nothing, top speed will most definately be sacrificed. Who goes fast in a wakeboard boat anyway? :-)
Old    waterdog2            05-31-2005, 12:18 PM Reply   
I kinda disagree with that order A new dual grind cam and some hydrolic rollers would definately add some pep to a 10 year old motor.
Old    Alpha_Beast (socalwakepunk)      Join Date: Dec 2002       05-31-2005, 12:21 PM Reply   
Lots of good advice above. Don't mistake HP for torque. For wakeboarding, would be best to improve torque. Start with the prop...
Old    warren            05-31-2005, 5:37 PM Reply   
Thanks for the imput:

I finally contacted Inmar. Looks like my engine is a pre-vortec, flat tappet engine. The current set up on the TBI will not handle any more H.P., even just adding vortec heads and intake would run the risk of running the engine too lean. Bummer! I'm looking into the Edelbrock EFI. Knowing that about my engine, I agree that a whole new motor may be most economical, dollar for end product.

For what it's worth, the Indmar guy said the GM ZZ383 crate motor makes a great marine use motor. Very wide torque band, with around 400 H.P. I found a guy who builds a similar "marinized" 383 with slightly less horsepower but even wider torque band. (over 400 ft lbs w/ max torque @ 4500 rpm). He will have it on a dyno tomorrow dialing in an Edelbrock EFI system. I am going to drive up and check it out.

For you prop maniacs, I am deciding between an Acme (they recommend The 801 13.5 LH 17.5 three blade nibral 1 1/8 bore .105 cup.)or the OJ XMP (13.7 x 17 x 1.125.). Both sound like good choices. The Acme is a little more expensive.
Old    Bob (bob)      Join Date: Feb 2001       06-01-2005, 5:26 AM Reply   
Hey let us know how the dyno run goes and see if you can sneak a peak at the numbers for us.
Old    Greg Davis (vortech347)      Join Date: Aug 2000       06-01-2005, 8:16 AM Reply   
A 383 built for maximum reliability would be a great setup.

As far as efi systems go the only real problem with tuning a boat engine is the fact that you can't use oxygen sensors. Otherwise, you could use just about any aftermarket efi unit out there. They all use some form of map or bap sensor to compensate for altitude and air pressure changes so once you get the engine tuned then you are good to go.

The best way to tune an aftermarket efi unit for a boat engine would be to have it tuned on an engine dyno where they could map the entire efi fuel and timing curves with a wide band O2 system. That way when you put the engine in the boat you will have a baseline tune that will be very close and you could tune it reading the plugs and by feel from there.

As long as the fuel system in the boat could supply the aftermarket efi system with enough fuel at the correct pressure then you would be okay. The fuel/water separator may be an issue but the current systems could probably be adapted if the one on your boat now is not adequate.

A supercharger would work very well in a boat but packaging with the tight engine cover and tuning it could be a real PITA.

Old    Karl De Looff (boarditup)      Join Date: Jan 2004       06-01-2005, 8:39 AM Reply   
The Acme is $310 shipped from me.
Old    Jeff Randol (jrandol)      Join Date: Mar 2004       06-01-2005, 3:45 PM Reply   
Go with the Acme CNC, they are INCREDIBLE props!!
Old    warren            06-01-2005, 10:29 PM Reply   
Bob,

I will let you know the numbers!

Greg,

Already checked into the supercharger,I'm not sure I want that thing sticking up outa the top of the engine cover. But wow, with just 4 - 5 lbs you can get as much as 100 additional ft lbs of torque on a stock motor. It can be used pretty successfully with a 4 bbl TBI.(Less money than Multi-port). It might look good with a nicely upholstered scoop on the back??? Mmmm I don't know.

Warren
Old    Stephen Higgins (srh00z)      Join Date: Jun 2003       06-01-2005, 10:47 PM Reply   
You would probably have to make fuel system upgrades with supercharging, boat motors typically have higher compression ratios than many factory cars, so lean conditions would be possible with supercharging. Seems like a centrifugal setup would work, but it would be tight and would require some custom bending for all of the tubes. On a side note, two years ago at the Masters I looked at one of the Nautiques that they pulled the jumpers with and it had a roots style blower on a stroked small block and was somewhere in the neighborhood of the low 500 HP range.

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