New Prop

Ok i have been reading all the post i can possibly find concerning props and can pretty much say WOW. I have gotten confused.LOL
I had posted i wanted a Prop for a 1987 Ski Nautique with a 454 and this is NOT a Barefoot Hull but a 2001 Hull. It currently has a 14 x 14 Federal right hand turn with a 1" bore and I have the 1.1 Tranny.
So i have been told a Acme 3 blade # 470 with about .040 cup taken out of it and I have been told a OJ 13 X15.5 # 428   So still dont know ! i do not ski or barefoot just ride the fresh water rivers and look good. I do want the boat to pick up some top speed but also have herd this is not likely with just a prop change over the Federal 14x14. So anybody have any ideas.

A 14" diameter Federal prop is dangerously close on an 87 Ski. You are going to rash the hull.

Who told you to get a 470? There are a handful of Acmes I would by before a 470 for your application. The Acme 1598 as C-Bass suggested is at the top of the list . Mighty expensive investment in looks for something under water...

Stock would have been a 650. I am not sure you will pick up much with the 750. a 330 hp big block just doesn't really need much more than 600-650 for the rpm it turns. Which manifold is it running?

Listen to the prop Gurus here on that boat.

I will be interested to know how it preforms with the Mechanical Secondaries.

13x15 *should* have been the stock prop as 14" would be tight on clearance... But who knows.

I don't anticipate you picking up any speed but the 1598 is the right prop for that hull and engine. 470 is too steep and the oj is waaaay to steep (it acts like it has at least 1" more pitch than the 470).

Didn't we already discuss the 1598 in your other thread?

Yes it has the Performer 2.0 on it and yes a new spread bore carb. Had engine out and ran on dyno ( yes my best friend builds comp racing engines for a living and owns the shop ) with old carb and manifold and changed on the dyno to new carb and manifold so yes it is better than before. Baseline run was 328 before and with carb and intake change it was 352 and moved the torgue up more in the power band but HP was till at about the same rpm due to stock cam shaft. The stock cast intake is restrictive along with the factory aluminum spacer plate that dont match up well causes reversion. I have a 4 hole spacer on a 20 degree angle between the carb and intake matched up with this setup. Along with a Davis Unified HEI Marine Ignition so i have a very hot spark.

So with that out of the way and again stating that my need will be only to ride and not ski what and how do you guys think the OJ 428 or the 1598 will will work? If the 428 is too much what will it do? Cavitate or just run too many RPM- Realy like to option that OJ has if it dont work return it and dose ACme do the same.

Again, the 428 is too much prop whether you have a 330hp, 350hp or even a 500hp 454.   It is unlikely your engine would pull it 4000rpm, you'll never get to peak power. It'll be a dog out of the hole and be a few mph slower up top.

1598 is the right prop for 454ci in that hull.

How'd you spin the dyno backwards?

performance = looks

SO WHICH ONE IS IT SMART GUY??

Ok, so not trying to stir the pot here, but just trying to learn... The stock prop was 13 x 15, and the recommended prop is the 1598 which is 13 x 14. I believe the common performance indicator is (and this is part of what I am trying to learn), if you drop an inch in pitch expect to pick up about 250 rpm's (again looking for confirmation).

So assuming the factory chose the 13 x 15 to maximize performance, if he dropped an inch in pitch, the revs would start to get above the peak performance, however moving to a CNC prop (such as the ACME) from a forged prop (like the factory would have shipped) also pull the revs down about 250 rpm because they are so much more efficient (again, seeking confirmation).

So if he has now warmed up the engine from 328 HP (essentially stock performance, btw impressive that a 28 year old 454 is still putting out close to stock HP numbers) to 350 HP, and also bumped up the torque numbers, wouldn't it make sense that he should be able to pull at least an inch more of pitch or 13 x 15. Of course their is no ACME 13x15, so you would have to go to the 224 which is a 4 blade, 4 blade equals more drag and is probably slower (right?) or the 1442 (my new favorite prop) which is 13.25x15. He would be going up a 1/4 inch in diameter (1/8 inch closer to the hull) which should not produce hull rash and have minimal impact on revs.

Ideally, go to an mini reunion, generally their are tons of different props floating around that could be tried. Not many prop shops have trial programs, I don't know what ACME's policy is but I do know they are great to work with.

Sorry Steve but your numbers and rationale are way off.

An inch of pitch is closer to a difference of 700-800rpm, all else being equal. At least on the acmes. It is very tough to compare 2 very different props based solely on their dimensions (which are often inaccurate or rounded) as there are a number of other factors that determine how they perform and how many revs they turn at WOT.

The advice given above comes from personal experience on how the props compare to each other on the hull/engin in question and others very similar. Too much info to repeat here while typing on he phone while driving in the rain on the way to WL... But a bunch of it is posted here if one were to dig around. Threads discussing bfn props are most applicable as they more commonly got the 454 and the 2001 hull performs very similar (in terms of size and efficiency) given stock-ish power levels. The bfn hull was notches to clear 14" diam props in 80-81 but all of the modern options are 13" or less so all of the same options would apply to a 2001 as well.

Ha no trailer yet... Grabbing the '79 at Larry's in a few hours.

Remember that you should have seen about a 200rpm difference between your 422 (15.5" pitch) and 1442 (15" pitch). The differences aren't quite as big on a 1:1 (theoretically 23%)... So maybe 600rpm difference for an inch of pitch on a 1:1.

I have not seen any difference in rpms in 3 vs 4 blades, all else equal. Performance changes a bit (4-blades have a little more out of the hole, 3-blades are faster) but rpm and pitch are consistent.

a THOUSAND? I thought my boat was under performing...

They are not fast to begin with but Dad put some little 2bbl on it so I'm going to change that back and it does have bottom paint too-

You might already have the fast prop on,for some reason Federals top out better than others,but in my limited experience it is only by a little. The others have a big difference in idle thru midrange where you really can use it.

Gary S wrote: They are not fast to begin with

Nobody said anything about speed. Leaving a thousand RPM on the table isn't helping anything.

13x9 oj might be a better place to start Gary.