New Prop

Earlier in this post I read a 750 CFM carb was being used. If the engine is not exceeding 5,200 RPM a 625 CFM carb is proper size for a 454. If you are looking to rev it to 6,000 by all means jump on the 750 CFM. When it comes to carburetors run the smallest one that can give you a proper fuel ratio at max RPM. The smaller carb will respond better from idle to Wide Open Throttle.
We built a strong 460 Ford for my brothers Jet boat. We knew the pump would limit RPM to 5,200 so we limited the Carb to a 650. We did not dyno the engine but I am sure it was 330 to 375 HP. It ran perfectly from Idle to wide open, never felt like it needed a little more carb. It burned clean to, the exhaust always smelled correct not over rich.
If the pump did not limit the RPM and the same engine was going to spin higher we would have needed a bigger carb.
Edelbrock, Holley and Carter all have charts out that tell you how much CFM a engine will use based on the RPM and displacement of an engine.

TRBenj wrote: And it's only run 66 thus far... None of this 67-68 nonsense.

And at that end of the scale adding 1 or 2 mph is a VERY big endeavor. Quite amazing that he has that bad boy running 66!

He's got a 2001 Zach... It doesn't have the same speed potential and can potentially get a little squirrelly when you wander into the mid 50's and above. I do agree that the 454 bottom end wouldn't be stressed with a bit more hp. Different heads with different chambers don't necessarily cause piston interference problems- the common large oval and rectangle GM heads play nicely with the stock bottom end. Of course the CR would be down in the dumps so a piston change or one of the less common smaller chamber factory oval heads would be advised.

And it's only run 66 thus far... None of this 67-68 nonsense.

Understood. We went over all this and he wanted me to put the New Brodix Race Rite heads on it still oval port but its a 50 hp advantage and you dont have to change the Pistons. If you go to a different head such as a Square port the cahamber is also different so Pistons would also be needed. You can make plenty of power with a oval port heads but not in the Budget and the Engine is very strong as it only has 480 hours on it so maybe next year or by then a faster boat all together. Lets face it the nautique isnt going much faster with current hull witout alot of other stuff breaking or causing trouble with added HP at its age.

gotta be careful, don't want to spill your rum runner

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

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.

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.

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-

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

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.

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.

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.

performance = looks

SO WHICH ONE IS IT SMART GUY??

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?