150 Evinrude RPM Range

[sharkboy]

I have my eye on a Grady White Tournament 192 with 150 Evinrude (1994). The broker let me take it for a spin and the engine ran great, and only has 153 hours! Only problem is I could barely get it to 5100 RPM trimmed out and 4 people in the boat. Small nick in the SS prop (sorry don't have the specs now), and I had a compression check done and all cylinders are 100-105 psi. Shouldn't this motor get closer to 5500 if propped correctly? I'm pretty sure this is the prop that came from the dealer when the original owner bought it.

 

[HighTrim]

Re: 150 Evinrude RPM Range

Welcome to iboats.

I would want that closer to around 5800 RPM at WOT, especially with todays fuels.

 

[Dhadley]

Re: 150 Evinrude RPM Range

Ditto. Even 6000 won't hurt that motor. I bet we can get you close, if not there by working the set up. I'll also bet the motor was mounted all the way down.

Nice boat, great motor. Should be a great combo.

 

[sharkboy]

Re: 150 Evinrude RPM Range

Thanks for your replies. I read several threads before posting so I've got a general idea about what's needed I think: check the depth of the ventilation plate while underway and maybe go down 2" pitch in the prop?

One question though: what is different about "today's fuels" than when the engine was manufactured in 94? I know gas can be formulated in many different ways, so does this factor in? Also, my assumption is that the top speed won't go down since the higher RPM should cancel out the lower pitch of the prop (and less drag if the engine is too low). I managed about 32 knots WOT during my test. I think that boat should be able to go about 35.

 

[Dhadley]

Re: 150 Evinrude RPM Range

Never lower the pitch simply to gain rpm, that's strictly a last resort. Work the set up first. Generally speaking lowering the pitch will reduce efficiency. Working the set up will gain efficiency.

As for the fuel - where do we begin? We don't have anywhere near the same fuel as we did in 94. Or 04 or 07. E10 is starting to show up around here and is causing problems we never saw before but we have to deal with it.

 

[sharkboy]

Re: 150 Evinrude RPM Range

Dhadley, I think I understand now. When you say to work the setup first though, I only know of two things I can change -- I can lift the motor up for less drag, or I can trim the motor as I'm running. Now, I'm used to constantly trimming my current motor (Evinrude 90) for best speed and efficiency, and I did trim this new 150 during my trial. The mechanic at the marina said he got it to 5100 and said "but I had it trimmed up good." So I'm pretty sure I've got that part right. So after I check the ventilation plate depth, what else should I check out? I mentioned to the mechanic that I was a little concerned and I'd like the WOT RPM to be a bit higher (like 5500 on my current boat) but he didn't seem concerned at all (although I've met many clewless mechanics). He just said, "maybe take the prop down a size" which I took to mean lower the pitch 2".

One more thing about fuel -- I doubt the places I fuel my boat would sell me ethanol fuel would they? I always fuel at my marina or one other place that's on the water.

You and the other people on this board all seem to really know your stuff, and I'm really glad I found this. Once again I appreciate all the help, and I'll be back for more questions no doubt.