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View Full Version : 14 X 18 Lh Prop Vs 13 X 13 Lh


MMCCAR12
10-15-2006, 08:55 PM
Who knows what the differance in prop performance is on power slot trans using a 13 x 13 or a 14 x 18 3 blade.

DooSPX
10-15-2006, 09:10 PM
Who knows what the differance in prop performance is on power slot trans using a 13 x 13 or a 14 x 18 3 blade.

a boat with the 'slot comes with a 14X18 prop. if you have a 13X13, you have the wrong prop.

MMCCAR12
10-16-2006, 10:26 AM
Thanks, I have a 14x18. Just saw the 13x13 as an option in the MC product data for 83. Is there anything that will give it a better top end ?

The thing already has more torque / pulling power than I require. Would like to go a bit faster if I could.

DooSPX
10-16-2006, 01:01 PM
well, with a Power Slot trans, most of the time, your going to be slower than a 1:1 trans by a mph or so... not always true, but most of the time.
one thing is that with a gear reduction trans, your rev'ed quicker, and the larger 14" prop doesnt help speed either.
look at boats made for nothing but top end, they have small dia. props with lots of pitch...
call acme or OJ and talk to them about what you want from your boat. im sure they can help you .

MMCCAR12
10-16-2006, 04:05 PM
Thanks for the info.

EricB
10-17-2006, 02:59 PM
Check your engine RPM's at wide open throttle. Top engine speed is supposed to be 4400 rpm's I believe. Going to a 13X14 pitch may give you alittle more top end, but you will drop a little out of the hole.

DooSPX
10-21-2006, 09:43 PM
I kinda forgot to add that. Thanks Eric, and good thinking!

if you have any other questions, ask these guys here!

M Shore
10-21-2006, 10:16 PM
call acme they are the best! they will get you the prop you need and if it isnt youve got 30 days to return

butter
10-23-2006, 02:18 PM
Check your engine RPM's at wide open throttle. Top engine speed is supposed to be 4400 rpm's I believe. Going to a 13X14 pitch may give you alittle more top end, but you will drop a little out of the hole.

I believe it is the other way around. You will likely lose a little top end (speed), but holeshot will improve. Your engine will be able to rev higher with the 13x14, but you will go slower at any given RPM, and your engine may be able to "over-rev" past the recommended WOT (4400 RPM?), which can cause damage, unless you exercise caution.

The 13x13 you saw listed in the product data for '83 is for a 1:1 transmission. To increase top speed, you generally need to increase pitch (say from 18 up to 19 or 20), but only if your motor can still turn up to the recommended rpms at WOT.

It is a good suggestion, above, to check your current RPM's at WOT. Acme will likely need that info to help you out.

Hunterb
10-23-2006, 03:04 PM
Actually I'm pretty sure going from a 13 to a 14 would increase your top speed, but you'd lose a bit of your hole shot. A 14" prop will theoretically travel 14 inches forward with each revolution. So, given the same engine RPM the boat will move farther forward and therefore faster. However, it is going to be harder to get the higher pitch prop turning because it's trying to do more work so it will be harder for the engine to 'rev up' resulting in a slightly slower hole shot. I suspect that you would see slightly lower RPM's at WOT with the higher pitch. Now if you increase your pitch and also increase your horsepower somehow then you may get more benefit from the higher pitch.

This may be completely haywire, but it's the way I've always thought about props and pitch and horsepower and speed etc.

Bruce

TRBenj
10-23-2006, 03:24 PM
Actually I'm pretty sure going from a 13 to a 14 would increase your top speed, but you'd lose a bit of your hole shot. A 14" prop will theoretically travel 14 inches forward with each revolution. So, given the same engine RPM the boat will move farther forward and therefore faster. However, it is going to be harder to get the higher pitch prop turning because it's trying to do more work so it will be harder for the engine to 'rev up' resulting in a slightly slower hole shot. I suspect that you would see slightly lower RPM's at WOT with the higher pitch. Now if you increase your pitch and also increase your horsepower somehow then you may get more benefit from the higher pitch.

This may be completely haywire, but it's the way I've always thought about props and pitch and horsepower and speed etc.

Bruce

That's correct. I believe Butter was also correct though- he was talking about going from a 14x18 (not 13x13) to a 13x14.

butter
10-23-2006, 05:22 PM
I believe Butter was ... talking about going from a 14x18 (not 13x13) to a 13x14.

Yep. Sorry I wasn't clear about that ealier.