prop woes....thank god for power tech!

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hammer250v8

Petty Officer 2nd Class
Joined
Nov 15, 2002
Messages
123
thanks god for power tech!<br /> i had a power tech 13.5/25 pitch prop(old one)and it wasn't turning the rpm's i wanted. bought a new power tech 14.25/23 pitch and it got even worse(5000 with 23-5500 with 25) bolth were 4 blades.sent the 23 back in exchange for a 14.25/19 and tried that yesterday.6000rpm's and hole shot is awsome. i'm only getting 60mph out of my 21 baja(3100lbs dry).do you guys think a 17 pitch would get me to 6500rpm?i've been told by Dhadley i should get as close to my 6700rpm rev limiter as possible for my motor. thanks for the help and sorry so long!...james
 
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Spidybot

Lieutenant Commander
Joined
Apr 4, 2002
Messages
1,734
Re: prop woes....thank god for power tech!

But...<br /><br />You don't tell what motor you have? Makes it hard to give any advice...<br /><br />Generally you should use a prop that suits your need (top end?) and keeps you within the recommended rpm range at WOT.
 
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Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: prop woes....thank god for power tech!

You need to get as close as possible (as close as your hull design will allow) to your target rpm by set up. Only a as last resort should you drop that much pitch.<br /><br />It sounds like the large diameter 19 is getting close. Now its time to play with X dimension, gearcase shape and possibly tweak the running surface of the hull. <br /><br />If you use the true (GPS) speed you can figure slip % and figure which prop to work with as far as slip % and lift.<br /><br />Good luck!
 
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hammer250v8

Petty Officer 2nd Class
Joined
Nov 15, 2002
Messages
123
Re: prop woes....thank god for power tech!

the motor is a 1991 evinrude 250 V8. even with my detwiler jackplate all the way up i still can't pull more the 6000rpm's.so you guy's think going to a 17 would be a bad idea? thanks...james
 
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hammer250v8

Petty Officer 2nd Class
Joined
Nov 15, 2002
Messages
123
Re: prop woes....thank god for power tech!

sorry...<br /> i need to add that the motor is set back 33 inches from the transom with a stainless marine 27 inch bracket and the detwiler is a 6 inch setback model. do you think this could be a problem? the boat is designed to have a big block in it!....james
 
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Hooty

Rear Admiral
Joined
Oct 2, 2001
Messages
4,496
Re: prop woes....thank god for power tech!

dhadley is da man. I think I would dink around with the X dimension like he suggested. You may have to move your engine up another hole on your jackplate.<br /><br />c/6<br /><br />Hooty
 
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