Turbo Prop on 115 4 stroke

[pokman]

Hey guys have a propping question. I have a 2001 18ft Bayliner 184 bowrider with a 2003 merc 115 4 stroke. I run a 17p aluminum quicksilver and by myself see about 5800 rpm 41mph. Me wife and kids a and loaded up 5600 rpm 39 mph. I also have a 15 p aluminum as my back up prop and this prop will run me over the 6000rpm max. Local prop shop has a 16pitch ss Turbo for $200. I have never used a turbo, understand they have more rake, do you guys think this will give me 1-200 more rpms over my aluminum 17p or because of the aggresive nature of the prop and it being stainless do you think dropping down a pitch will even do anything for me. I should say I am very happy with my 17 quicksilver would just like to get that extra couple hundred rpms so she runs right at 6000rpms.

 

[SparkieBoat]

Re: Turbo Prop on 115 4 stroke

5600-5800 RPMs is a great happy range for your motor..stay away from 6K. I recommend no change.

 

[pokman]

Re: Turbo Prop on 115 4 stroke

sparkieboat,

Just curious as to what your saying because I thought you always wanted to be right at your top rpm especially on these merc 115 4 strokers. I never go over 6000 just use the 15 pitch for pulling up fat guys on skis. I was more looking at the 16p turbo because when loaded up I am running at 5500-5600 and looking for 200 more rpms, I am more curious as to if the turbo would do that. The prop I really want is a 16p vengeance but don't have 350 to drop right now.

 

[Texasmark]

Re: Turbo Prop on 115 4 stroke

Don't know about the 4 strokes, but I run my 2 strokes at 5800-6000 WOT all the time....they love it. I guess your prop is alum. SS usually have thinner blades, higher rake and are cupped. That means that they are more efficient for the pitch for the thinner blades are more efficient (knife cutting the water vs a baseball bat) higher rake, means the the blades are laid back more which raises the bow which gets more of the boat out of the water reducing the wetted area, thus reduces drag, thus increases mph for the force applied, and cupped which adds about 2" more pitch at WOT. So what else do you want? Grin.

Mark

 

[SparkieBoat]

Re: Turbo Prop on 115 4 stroke

I have a 2003 F115, I have spoken at length with a Yamaha Master Tech. He told me to keep mine under 5800, but over 5500 at WOT. He post in here some times and on another site. but he really knows his stuff..the 2003 Yamaha four stroke and mercury 4 stroke are the exact same motors. 5600 RPM is no where near lugging that motor..2 stroke mercs can really tach out, I have heard of many stock engines running over 6500 with no trouble, just add extra oil to gas. the 150s from the late 80s and early 90s are bullet proof. I got me one of those puppys and it will stroll. I would rev it to 7K and not be scared.

 

[pokman]

Re: Turbo Prop on 115 4 stroke

Thanks SParkie that is good to know, well maybe I will just try the the turbo as it should keep my rpms at or right under 5800 anyway. I was more curious if anyone had any thing to say about the turbo brand prop. Sparkie how do yo like you yamamerc? This is my first 4 stroker and so far I am loving it, mine is also the 03 even though I know it is a different gear case than yours.

 

[SparkieBoat]

Re: Turbo Prop on 115 4 stroke

I hate mine..when it runs it is great..but parts a stupid pricey and your average outboard mechanic cannot troubleshoot them. as a matter of fact most yamaha techs cannot accurately trouble shoot them..most mechanics just start throwing parts at them, boy can that get costly. they have valve issues, lots of fuel related issues and ECU problems caused by stuck ISC valves. a inline filter was like $50..I almost shot the parts guy, but he promised me he was not ripping me off and that was the actual real price, so I let him live. in the forums I have read some real horror stories. I would sell mine in a heart beat, I have had it for sale now for a year...no takers so far.