Gaaaa! It's a beast, what rpm to shoot for

[jim dozier]

I finally got my 1997 115 Evinrude looper in the water for a test drive. I figured the 15" Mich Wheel prop that came with it was probably going to be too small because it was on a bigger boat. My boat is a 17 foot semi-V with pad hull. After giving myself several nose bleeds from the hole shot I checked the max rpm. It would jump to 6000 rpm and I let it bump to 6200 rpm for a moment. I'm guessing it might have gone to ~6400 rpm but I didn't want to hurt it. <br /><br />So what is the recommended max rpm on this engine. Someone, Walleyehed I think, suggested in an earlier post that I prop it for 6000 rpm. Is that correct? The Iboat prop web page lists 5500 rpm as max for a Johnson 115 but I don't know what year, crossflow or looper, or if it makes a difference. The service manual is fuzzy on the issue. I'm at 15" pitch now with an old cupped aluminum prop. Should I go to a 17" which should take it to about ~6000rpm or go to a 19" which should take it to about 5600rpm. This is all based on an estimate of 6400rpm max which I never acually got to. At 6200 rpm there was more to go I just don't know how much. What do the OMC prop experts say?

 

[Barnacle_Bill]

Re: Gaaaa! It's a beast, what rpm to shoot for

Here is an excellent article on props.<br /> http://www.boatfix.com/how/props.html

 

[ob]

Re: Gaaaa! It's a beast, what rpm to shoot for

I'm guessing 19" pitch will keep you within the recommended rpm range of that engine.I'd shoot for around 5800-6000 wot rpms.Final selection of course will depend on water test results and type of performance desired.A 17" will surely be a bit quicker out of the hole(good ski prop), while the 19" will give you more top speed.<br /><br />Congrads on your recently put to use bullet.

 

[jim dozier]

Re: Gaaaa! It's a beast, what rpm to shoot for

^

 

[jim dozier]

Re: Gaaaa! It's a beast, what rpm to shoot for

^

 

[walleyehed]

Re: Gaaaa! It's a beast, what rpm to shoot for

Get your hands on a 19 and see where your at...that set-up should darn-near spin a 21 close to 5800.

 

[Dhadley]

Re: Gaaaa! It's a beast, what rpm to shoot for

Wanna try a Turbo Lightning Jr? 13 1/2x22. Lots of lift.

 

[jim dozier]

Re: Gaaaa! It's a beast, what rpm to shoot for

I'm on a budget. I have an old 19" alum off of my Suzuki but it rubs on the inside of the back of the gearcase. My plan is to borrow, hopefully, or buy an inexpensive alum prop to check the size/rpm and then get a stainless when I know what I'm looking for. I use the boat for multiple things. I water ski, I fish, and I zoom. I'm on Tampa Bay mostly and its pretty choppy. I probably can't afford a top of the line stainless prop, I may try to pick up something good but not extravagant. I appreciate the tips. It looks like I'll start with the 19", that's the info I was looking for.

 

[Dhadley]

Re: Gaaaa! It's a beast, what rpm to shoot for

I also think youll end up with at least a 21 on that pad bottom hull. Just like Walleyehed suggested. <br /><br />

I probably can't afford a top of the line stainless prop

Hummm....I reread my last post several times but I dont see where any money was mentioned. <br /><br />But, if you dont wanna try it thats OK too. (Hint -- never turn down a chance to try anything... well OK, there are some things one shouldnt attempt)

 

[jim dozier]

Re: Gaaaa! It's a beast, what rpm to shoot for

Dhadley, I'll try anything once, things I like I'll try em twice. If you're offering I'll take you up on it. You can contact me by email at jimdozier@earthlink.net

 

[Dhadley]

Re: Gaaaa! It's a beast, what rpm to shoot for

Atta boy! You got mail! Well....in a minute anyway!