20 hp johnson prop question.

[puddlejumper79]

I've been researching and can't find a definite answer, I'm looking to run a cleaver or chopper prop on my run-a-bout. It's a very small mini toth with a 20hp johnson. The boat is very light, but not a super fast hull design, currently on gps I'm getting 27mph, I plan on doing the 20 to 35hp swap parts, but for prop selection I have no idea what pitch to get, I've seen youtube videos of guys running 18 pitch on slightly modded 20's and getting close to or over 40mph, so here's my questions....
1) can I run that big of a pitch?
2) where is the best place to purchase a performance prop?
3) anything I should know about when ordering a prop?

thanks.

 

[steelespike]

"mini toth?"
What year is the motor?Before 77 there is a 25 based on the smaller 22 cube block.5500 rpm.
If you have the 31 cube 20 the 30 and 35 were based on that block,
What size is the prop.The 18 hp based on the 22 cube was rated for 27 mph on a light reasonably fast boat.
Some pictures of the boat will help.

 

[puddlejumper79]

No Title

This is the little guy in question, mini toth marine. The motor is a 1992 20hp. Stock prop with some dings.. just wondering what the best cleaver or chopper upgrade would be?

 

[steelespike]

Unfortunately I can't be too specific but If your going to be messing with props you definitely need a tach.We also need your present prop size and light load wot rpm and gps speed.Prop size should be under the prop nut or near the base of the blades.
With your present prop size and rpm we can tell a lot better what size prop will work.
There is a guy named Ron Hill that builds props.I don't think he does small props but he may be able to give you some suggestions.
I think you can do better than 27 without going to a specialty prop.
You might check the Turning point hustler and rascal props in aluminum. These are said to deliver ss performance at al prices.
I note the motor is raised up some;have you tried higher? The Hustler/Rascal props may allow higher setup.
Maybe you could slide the seat back and gain a little.

 

[puddlejumper79]

https://youtu.be/amJ3mV2gyqg



thanks for your insight! I'll get some more specifications for my prop, I'm currently not running a tach. I just got excited seeing a youtube video of a 20hp johnson with a 18 pitch with a jack plate doing 43 mph, I'll try to copy the link. I would love to get around that speed once everything is done, I just figured the prop would be the first step.

Thanks again

 

[Chrisravosa36]

If your going to dump some good money into a prop, Ive heard some good reviews off a prop shop that works of Ebay (prop18 or 19). Great stainless props at a good price. You can shoot him asking whats the best for your setup. Also with racing props, you should go a few pitches higher than normal.

 

[puddlejumper79]

Very good information! Thank you! I'm going to check that out.

 

[steelespike]

I saw the video before, a year or more ago. Pretty sure it is what they call a "surface drive".You may note it throws a lot of water
back.The prop is designed in such a way that part of the blade comes out out the water this allows the motor to rev easier yet it is designed
so the surface blade still has thrust by throwing water back.I think the basic design dates back to the 1930s