Best WOT rpm?

Frank I.

Seaman Apprentice
Joined
Nov 13, 2004
Messages
32
Whats the best wot rpm for a johnson 130 90 degree looper.I get 5500 with a 14.25 * 19 aluminum.I want to get a stainless prop,anyone any advice on what type(been looking at michigans ballistic)thanks for any info
 

Dhadley

Supreme Mariner
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Feb 4, 2001
Messages
16,978
Re: Best WOT rpm?

Your target is 6000 with an average load. The rev limiter is at 6700. <br /><br />The Bull-istic is a fairly inexpensive prop. With props you generally get what you pay for.
 

Frank I.

Seaman Apprentice
Joined
Nov 13, 2004
Messages
32
Re: Best WOT rpm?

It's a 19ft key largo CC, 18 degree deadrise & 96" beam.Boat & motor are about 2400lbs,with me gas and gear probably 3000lbs.The boat runs 41mph at 5500 with a 14.25*19 aluminum Hustler prop.Thanks
 

Dhadley

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Feb 4, 2001
Messages
16,978
Re: Best WOT rpm?

Very good info. <br /><br />Alright, we're at almost 20% slip. That can be better. <br /><br />With an aluminum prop we assume you dont have a jackplate. Make a note on your water pressure to add to your baseline info. <br /><br />I'd almost bet that the motor is mounted all the way down on the transom, maybe 1 hole up. Can you use all your trim range without losing bite?
 

Frank I.

Seaman Apprentice
Joined
Nov 13, 2004
Messages
32
Re: Best WOT rpm?

Just went outside to check(and its cold!)I dont have a jackplate.The motor is one hole up and its a 25" shaft.I can trim it out a good bit ,but it does loose bite at a point
 

Dhadley

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Feb 4, 2001
Messages
16,978
Re: Best WOT rpm?

Oops!!!<br /><br />My bad! I should have asked before if it was a 25". Some of those have a different gear ratio than the 20" motors.<br /><br />What year motor is it? The model number will tell.
 

Frank I.

Seaman Apprentice
Joined
Nov 13, 2004
Messages
32
Re: Best WOT rpm?

I forgot to tell you that the gear ratio is 2.25:1(you probably used that in your slip calculation)
 

Dhadley

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Feb 4, 2001
Messages
16,978
Re: Best WOT rpm?

Yep, so we're doing a lot better at less than 10% slip. Thats very very good. Is that GPS speed?
 

Frank I.

Seaman Apprentice
Joined
Nov 13, 2004
Messages
32
Re: Best WOT rpm?

Yes that is gps speed.I know that the 6o degree engines liked to see 6000,was not sure on my 9o degree.Should I step down to a 17 pitch
 

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: Best WOT rpm?

No. Going down in pitch is the last resort to increase the rpm's with an outboard. Stick with the 19" range, especially for testing. Theres no reason you cant swing one. Once we test the ss props you can start raising the motor. That alone will make the set up more efficient. Less drag etc. Not to mention the ss props will most likely have more lift (reduces wetted surface and again reduces drag while increasing efficiency).<br /><br />If youre not planning on adding a jackplate, and theres nothing wrong with not adding one, we should look at Stilettos in the 3 blade style. By all means if you have the opportunity to try any brand, do so. The more info you have the better decision you will make later.<br /><br />The style gearcase you have now uses the V6 style props. Thats good. Larger diameter is always better in my opinion. <br /><br />Let me know whaen your ready to test some. I may have some. I may even have a 19 Ballistic.
 

Frank I.

Seaman Apprentice
Joined
Nov 13, 2004
Messages
32
Re: Best WOT rpm?

Thank You Dhadley,its a pleasure to talk to someone who knows there stuff.I'll test in the spring and keep in touch(already winterized)HAPPY HOLIDAYS
 
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