Prop suggestions new 351w

I don't imagine a lot of guys have info on hull performance numbers on this site for that boat. Just as a reference most 240 HP 351W engines in 1982-1988 Ski Nautique 2001's (2400 dry weight) run between 4400 and 4600 RPM with an Acme 540. With an Acme 542 (equivalent opposite rotation to the 543) these boats would run between 4600 and 4800 rpms.

What ratio is the tranny on the Ski Nautiques?

Billings area. Wish I was in the flathead area.

TRBenj wrote: [QUOTE=svxwilson]The correctcraft forum doesn't have nearly the amount of helpful people either. I have tried both.

Well thats certainly not going to make you many friends here.



I was frustrated i apologize. I will repost on that mastercraft forum my apology Was not trying to piss anyone off I posted here and people basically told me to find another forum. Got no help. I know I have a low production boat. I have had a hard time finding info on it. But thank YOU for your reply. Yes I have a reverse motor with a 1.23/1pcm and a left hand prop. I do not know enough about Ski Brendella to tell you if that was the original config or not. But it's what I am working with.

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www.usmarineengine.com

Is where I got the long block from. They explained the extra HP came from the cam and higher compression. Please forgive my engine ignorance. I can turn a wrench and replace parts but by no means am I a mechanic.
From their webpage
"High quality components that equal high quality rebuilt marine engines. All of our marine engines come with new rings, new springs, new pistons, new valves, new push rods, new timing set, new rockers, new brass freeze plugs, new push rods, new bearings, and new lifters. Head castings, crankshafts, camshafts, and rods are all machined back to marine engine specifications and blocks are bored oversize."

I reused the holly carb and intake from old engine. The engine builders had to search for the reverse parts because they are harder to find.

I talked with Greg at ACME and he recommended a 4 blade 13.5x14.25 model 1793. So I ordered that, he was convincing about their customer service that they would exchange until I found the prop that works best with my boat.

I know 50mph is something I won't get to. But close is what I am aiming for. I do mostly slalom skiing and cruising up and down a very large lake. So lower rpm at higher speed is the desired result.

I have never been pulled out of the water as fast as it can do right now with the current prop ACME 543. But 4000rpm was 31-32 mph. I never took it to wot with that prop and current engine only had it out once after install so I was breaking it in and I wasn't sure if wot would be a good idea first break in trip out. The engine builders said the desired rpm was 4200 and not to exceed 4600.

Once again thank you for your help. I will happily listen to anything you have to say or recommend. If there is a better forum for my peticular brand boat then let me know.

EJ OJPROP who works for OJ said "We supplied Brendella with 14 X 16's as original equipment with that ratio. I would offer a 13.7 X 15.5 XMP for that set up"

Do you think the 4 blade 13.5x14.25 is a poor choice? I should have it Friday. I ordered a prop pulling kit and the 1793 Monday. I ordered it new from acme so I can return and exchange till I get the one I like. Can you explain the logic between the 3-4 blade prop choice. I understand how size and pitch affect I don't understand how the extra blade affects everything?

So let me get this straight.... Put the new prop on and take it to wot? Take note of rpm and mph at wot? I would not mind having more than one prop also. One that is better for pulling a large mammal like 250lbs up and one that is for top end and slalom skiing. I can get up behind a old tired 86 bay liner with a 2stroke that topped out at 20'ishmph with me on a slalom. I am sure I can get up with a top end prop behind my 351. So ultimately I will be looking for 2 props eventually after I sell my 543.

There is no need for 2 props with that powertrain. A slightly modified 351w and 1.23 in a fairly light ski boat, propped for all around use will come out of the hole better than 95% of tournament inboards. Including most Chevy powered boats made in the last 10 years. The only boats I can think of that might have an advantage are the ones with greater reductions (like the 1.5:1 MC Powerslots).

Yes, WOT RPM and speed are the numbers we need. If you can verify theyre accurate, that would be ideal. Get a shop tach and verify the one in the boat is accurate and bring a GPS along with you that can capture your max speed.

The only GPS I have is through my smart phone. I have a app I use for the truck to know how far off my speedo is with big tires. It seems accurate. The lake I go to has service good enough to run the app. As far as the tach I believe it's accurate but have never actually tested it. My speedos in the boat froze up the last trip out. They are both stuck on 20mph. I will be looking into how to fix that next. Might even do a GPS speedo then I won't have to worry about it..... Ever. I can't remember riding on a boat that actually had functioning speedos, they always seem to have issues and I was excited when I bought mine because it had 2 functioning speedos.

TRBenj,
Thanks for the explanation. Make a lot of sense. Now who makes the 1.25:1? Supra used the 1.23:1 just as CC did. Only difference is the CC takes ATF and the Supra take 20-20W engine oil. (weird)

So that explains why my HO supra (extremely light boat!) has a run for its money when up against a regular 230HP MC from 84 or 85 (one is black other blue, the blue one!)

Now did PCM really gain 10hp by leveling off the engine with the new 1.23:1 transmission? They advanced the timing by 4 degrees at base and leveled off the motor and gave it a new paint job. Did that really give the 240HP for the Power Plus that my 89 CC has over the 230HP that an 88 and below Martinique would have?

Sorry for hijacking thread! Just some questions that I would like answered!

Thanks,
Joe

Hmmm. So I have an 80's PCM 1.23:1 in the 92. Whats the "buzzing" you are referring to? Both of my transmissions are fine. My CC tho very low on ATF when I bought it.

I'm not so sure about the slow top end. My rpm and mph are very close in hand. WOT @ 4,400 RPM = 44~45 MPH. I'm not sure what the MC is capable of tho.

And yes, my friend's MC and my Supra are nose to nose. When I put the comp in the water last fall for the first time in 2 years, the MC was near. Met up and then had a little "race". We both punched it and he just about beat up and out, after that I started to just barely pull ahead. But it was a very short "race".

While he may beat me in speed, I beat him in sound!

omfg this thread is still going on???

understood, tim's being very generous regurgitating it all

I got 41mph at 4200 rpm. I also started a new thread for the new results. More details there.

The torque of the RH prop offsets the weight of the (starboard sitting) driver to some degree.

TRBenj wrote: If you can verify theyre accurate, that would be ideal. Get a shop tach and verify the one in the boat is accurate and bring a GPS along with you that can capture your max speed.

Like Tim says are you sure those figures are accurate? Forget the 13x11, less pitch,the 11, will increase your rpm