I have a Ranger 482V with a Johnson GT 150, currently have a 24 pitch SS prop, but I'm only getting @ 4700 rpms--I am thinking of purchaasing a 21 pitch....any ideas--will this get me more RPMS (too many?)--just right? Not sure what the Manufacturer specs are for the Johnson (1990 model). Please help!!! Thanks!

Spaz, is it the Renegade 4 blade prop or a 3 blade Raker? Have you always only achieved 4700 RPM's at WOT ( Wide Open Throttle) or, did it recently start running slower?

That Johnson 150 is spec'd at 5500 RPM's max. I use a 23 pitch Renegade and get close to 5300 at WOT and am very satisifed with the overall performance on my TR18 Triton with an Evinrude 150. The 23 pitch Renegade 4 blade, considering the cup on the blades is closer to 24 pitch in reality, but on the wheel it says 23. The 21 pitch that you mentioned will spin faster, but your speed would go way down. You would hit 5500 early. The 21 might be a good prop for pulling a skier or stumps since you'll have more torque but a lot less top end.

I have a great Prop Calculator software tool that I can send you so you can see what the different speeds are for the different pitch props, etc. Email me and I will send it.

If your max WOT RPM's have recently dropped to 4700 from what used to be 5200 or so, you may have some powerhead problems.

Hope this helps some,

Bob

Spaz, is it the Renegade 4 blade prop or a 3 blade Raker? Have you always only achieved 4700 RPM's at WOT ( Wide Open Throttle) or, did it recently start running slower?

That Johnson 150 is spec'd at 5500 RPM's max. I use a 23 pitch Renegade and get close to 5300 at WOT and am very satisifed with the overall performance on my TR18 Triton with an Evinrude 150. The 23 pitch Renegade 4 blade, considering the cup on the blades is closer to 24 pitch in reality, but on the wheel it says 23. The 21 pitch that you mentioned will spin faster, but your speed would go way down. You would hit 5500 early. The 21 might be a good prop for pulling a skier or stumps since you'll have more torque but a lot less top end.

I have a great Prop Calculator software tool that I can send you so you can see what the different speeds are for the different pitch props, etc. Email me and I will send it.

If your max WOT RPM's have recently dropped to 4700 from what used to be 5200 or so, you may have some powerhead problems.

Hope this helps some,

Bob

I have always heard that one pitch equals 200-300 rpms. And extra blade is around 150 RPMs. Assumming nothing else is wrong with the motor or boat, than it sounds like your thoughts would be correct to down size the pitch.

Is the tachometer really working right? Are you sure? Tap it a few times until the desired RPMs display. That's what i have to do now and then.

I deny any claims to knowing anything about this subject.

Thanks Bob! I was wondering about top end speed. I took it out today and the best I could do was about 51 at 4850. I was hoping to gain a little in top end--what would you suggest? Also, you can e-mail me at oodles7@excite.com

Spaz, I plugged your RPM's into the prop calculator. The gear ratio for most of the Johnson/Evinrude lower units is 1.86. It is on my 98 model, I have the service manual and it lists the specs. Slip was entered as 0.9. Depending on your boat style, wind, chop, etc, slip could vary, but 0.9 is a close starting point. With a 24 pitch prop and RPM's set at 4850, your speed calculated out to be 55.5 mph. Changing the prop pitch to 21 and leaving the RPM's at 4850 yielded a speed of 48.9 mph. But, the 21 would turn faster. I'll email you the prop calculator and you can plug in the numbers yourself. It is a .exe file called props.exe. Save it to your hard drive and execute it from explorer or the Run program.
If it was a 24 pitch prop that you were running today and your RPM's only hit 4850 and your prop doesn't have a bent blade, I'm thinking it sounds like you have a motor problem. Have you had the compression checked lately? Bob

Thanks again Bob for the info. I just had the heads worked on (Compression checked out ok) and the water pump replaced. I also had them do a link and sinc. Seems to be running great, so I don't think I have a motor prob. I have decided to get the new prop re-pitched to 23 or re-pitched to a 22 with some cup. What's yr thoughts?

Spaz, glad to hear your compression checked good. Is the prop you are talking about a 3 blade or a 4 blade? Why is it a new prop? What did your old prop do RPM wise? Did you get the Props.exe file that I emailed to you at oodles7@excite.com? When you say that the motor is running great, do you mean at WOT you are hitting in the 5200 RPM area?
I don't know how you would change the pitch of a prop from 24 to 22. I think there is a max amount of adjustment that a professional prop shop could make. I would trade it for another prop that is the correct pitch instead of trying to have it re-pitched. If you got that Props.exe file that I sent to you, you could plug in the different pitches and it would tell you your speed and your RPMs. Bob