Tech Help with prop for top speed "plz"

[Hoosier Daddy]

Hello, I have a 1994 Nitro 190TF w/150XRI fuel injected Merc. To the best of my knowlage, I have a 13.5 X 25 SS prop (the prop was spun and dented badly and is now in the shop). I can get 55-60mph now with a WOT-rpm of 5800-6000 I am trying to acheive a max top speed. Can anyone give some idea's on what the normal prop for this boat/motor should be?. And the prop that would acheive the best results for top speed w/ safe rpms??????<br />THANKS FOR ANYTHING YOU HAVE!!

 

[rodbolt]

Re: Tech Help with prop for top speed "plz"

looking at your RPM your about at the top now.<br /> you may try a 26 pitch and lower your max RPM to about 5500 or so but acceleration may suffer.<br /> talk to your propshop and get the local input. I dont mess with bass boats much anymore<br /> good luck and keep posting

 

[Dhadley]

Re: Tech Help with prop for top speed "plz"

If I remember correctly the XRI has the smaller gearcase. That reduces drag but the trade off is you have to run a smaller diameter prop. If you can run a larger diameter, I would look in that direction.<br /><br />It would help if we knew what brand prop you are running now. Perhaps there are props with more lift built in. More lift reduces drag and therefore you might possibly be able to run more pitch for more speed. I think your RPMs are right on.<br /><br />I believe the Nitro has a pad bottom so it should respond well to prop changes. If you are indeed totally serious about top speed on that rig I would contact Mazco. John would know for sure but I bet an HP-4 would work well. Depending on your set-up maybe even a RE-3 or RE-4.<br /><br />When you find out what brand prop it is let us know.<br /><br />Neat ride. Good luck!

 

[walleyehed]

Re: Tech Help with prop for top speed "plz"

Kinda funny... in a way, that we let a MERC XRi slip into the JON/RUDE forum....!!!!!<br />Dhadley is "the" final word on props, but I will second the Mazco for what it's worth...<br />We've got a pair of 2.5 Mercs with HP-4's here on Texoma at our facility, and they are producing some hair-raising numbers...

 

[Hoosier Daddy]

Re: Tech Help with prop for top speed "plz"

Thanks, you guys are the best!!! Sorry about the merc being in here, but when you want the best advice in a hurry, I just seem to like it here!!!! Again thanks for all the help everyone has givin for all the ??'s I have asked in the past. And for this one too. I will look into a Mazco right away. I will try to let you know how it goes. P.S. Im a johnny guy. I am helpin a merc friend get the most out of his nitro. And yes you guys are getting all the credit, you deserve it.

 

[Dhadley]

Re: Tech Help with prop for top speed "plz"

Thanks for the kind words but if your friend gets Mazco to make a prop, you'll find out who gets the credit! Lol!<br /><br />When you talk to John have you friend tell him exactly what he's looking for; strictly top end with a light load, best handling at speed with a tournament load etc. <br /><br />Johns an incredible prop guy. He's built every one of my drag and "hot rod" props. You can have all the power in the world but if you cant get it to the water, it aint doin nobody no good.