Back to the main site

150HP WOT RPM

B

BucketsII

Well-Known Member
Messages
60
Reaction score
24
So today I took my 23Slx out for the second time. It is at 3.5 hours and I took it to wide open throttle because break-in procedure said i can do it for less than 5 minutes and I wanted to see how it performed. My 150hp LB Yamaha has a merc mirage plus prop 15p which they are changing out due to prop chatter. Today at WOT with 6 adults on and flat seas the highest RPM it got was 4800 I saw some Yamaha performance bulletins and they report 6000 RPM at WOT. Although they did the test with 2 adults- would that make a difference?
 
I'm certainly no expert but that doesn't seem right at all.
 
6 adults is a lot of weight unless you are around 125lbs. I am not. A mirage plus will not work well on a outboard motor. I have a 15p Enertia that will give me around 6000-6200 rpm when trimmed with just me in the boat. With 6 adults I'm in the mid 5000 range. What prop are they getting for you?
 
I believe they said Yamaha sds same pitch. Guess I will mention the 4800 WOT RPM to dealer and have them check it out while they are here.
 
That's a lot of extra weight... but I'm not sure what wot should be..never been wot with a bunch of people on board. But a prop can make a big difference. I had a 4 blade turbo originally, great out of the hole but wot was around 5k, switched to sds and now wot is around 6k.
 
So the weight affects the RPM as well as the speed. I thought it would just affect speed. I will wait until they switch out the prop. and try WOT with only 2 people like Yamaha did on their performance test and see if it comes in between 5000-6000 like the manual says. Thanks to all for the input.
 
I think weight can have some effect, especially if the people were all sitting up front and the motor had to work harder to plow through the water. But I don't think it would have anywhere near THAT much of an effect. Even if you get up to 5000 with 2 people, that's not acceptable. The dealer needs to help you dial it in to get close to the max rpm with a light load, and then you have room to go down when the load is heavier, the toons get dirty, etc. Potential adjustments include motor height, prop pitch (although the 15p is pretty standard for people on here with 150 yamahas), etc.
 
As much as weight is an issue trimming the motor is equally important. I can see a drastic difference in rpm as I trim up at wot.
 
I would check how it runs with just one or two persons in your boat for comparison. I have a 22SFXAPG SPS w/Yamaha 150 Reliance SDS. I get somewhere around 6100 RPM WOT running around 39-40 MPH. I am pretty sure when I have 4-5 persons in the boat I still get around 6K RPM WOT, but the speed drops to around 37-38 MPH.
 
Do yourself a favor and leave the neighborhood at home while breaking in your motor. You need to concentrate on your boat and the engine.
Your engine is a Yamaha and you should put a Yamaha Reliance 15 pitch propeller on it. With 2 people and 12 gallons of fuel, you should be seeing 6000 rpms. If your engine runs faster than that, go to a 17 pitch.
My F150 on a 24SSLX is mounted up one notch or 3/4 inch higher on the transom. It is perfect with very low prop slippage.
 
forgot to state that my prop size is 14.5 X15. I have had a Solas and Reliance prop on my motor, both the same size and they turned basically the same RPM. I think I may have gained around 1 MPH with the Reliance. It was noticeable a heavier made product. For sure I get smoother engagement and no prop chatter with the Reliance.
 
+1 on the Reliance prop.
 
Thanks for the advice. Dealer still waiting for the Yamaha reliance prop. They said that Yamaha does not have stock and they are trying to get one for me.
 
You must log in or register to reply here.
Back
Top