Evinrude 150 hp prop size

[randyray41]

I have a 1986 Evinrude 150 hp motor on a 1986 17.6 " stratos fish/ski. The current prop is a Raker 14 1/2 x 22. The boat will only turn about 4300 rpm wot and run about 42. Is this the correct prop or do I need another to increase my top end speed?

 

[cdn-pk]

Re: Evinrude 150 hp prop size

your rpms and way too low, should be 5600rpm. must take you a long time to get on plane. need some more info about your sent up, like if your motor is mounted properly but if it is then a 17" pitch might get you around 5300rpms... but it's not an exact science.

 

[Titanium48]

Re: Evinrude 150 hp prop size

Your WOT RPM is too low for your engine to generate maximum power. You want at least 5000 RPM. You might try a 19p prop. Depending on how much your RPMs come up, you may want to go to a 17p. Don't change props unless your are sure there's nothing wrong with your engine though.

 

[randyray41]

Re: Evinrude 150 hp prop size

Far as I know the engine is mounted properly. Mounted to a jack plate.

 

[steelespike]

Re: Evinrude 150 hp prop size

History seems to indicate that a 17" pitch should solve your propblem and is more typical
in a setup like yours.
Stick with a similar model prop.As mentioned above these results are approximate.

 

[randyray41]

Re: Evinrude 150 hp prop size

The engine runs fine except for a low idle rpm... other than that there is nothing wrong with motor other than its 25 yrs old.

 

[randyray41]

Re: Evinrude 150 hp prop size

14 1/2 X 17 is what you recommend?

 

[cdn-pk]

Re: Evinrude 150 hp prop size

on my 1986, 120hp on a 19' open box. i used a standard 14x19 Aluminum and would get top rpm of 4800 (too low) and 45mph. but my hole shot sucked, took forever to get on plane and always had tons of carbon build up in the engine.

on iboats i picked up a michigan wheel 13.75" x 17P vortex.... but it had a cup on the trailing edge. but it increased my rpm to 5000 and no real change mph.

Then i got another 13.75 x 15p vortex, same line with cupping, boosted my rpm to 5400rpm, great hole shot and actually increase my mph to 47-48 (i wasn't expecting that).

after all that i borrowed a buds, 17p with no cup and it gave me 5300rpm and about 45mph.

so not sure if i helped you any but titanium is correct. make sure your engine in in tip top shape first! and your not sitting too low on the transom.

cheers


so the pitch and the prop blade weather standard/raked/ cupped all affect the performance.

 

[ufm82]

Re: Evinrude 150 hp prop size

randy- I run a 19' center console with a '93 Merc 150- with a 19 pitch Tempest I turn 5600 rpm @ 51 mph GPS. Your boat is smaller, same horsepower and has a faster hull. (It's basically a bass boat with a walk-through windshield.) The 22 is too much- you should drop back. BUT, you are off by a lot of RPM and if everything is running properly you'd need to go down a lot of pitch. Makes me wonder if the engine is running as it should be. Your rpm range is 4500-5500 and obviously you want the higher number. Check the anti-ventilation plate height (should be about 1" above the keel or close), proper engine operation, ( compression check wouldn't hurt), maybe a decarbon regimen and a different prop. You SHOULD be able to turn a 19 but other factors may prevent that. And your holeshot will be better with the 17 but you'll sacrifice speed. A 150 on that boat should hit 50 pretty easily.

 

[randyray41]

Re: Evinrude 150 hp prop size

I lowered the jack plate some. I was running around 45 to 46 hundred before I lowered plate. I may need to raise it just a little. Before I lowered it when I made a turn the prop would lose bite. I was thinking I should be able to hit 50 to 52 in the boat. The engine was "decarboned" a couple months ago and the compression is good on all 6 cylinders.

 

[ufm82]

Re: Evinrude 150 hp prop size

In that case the drop in pitch will definitely help- you'll gain RPM and even with the drop in pitch your speed will rise. Remember, it takes HP to turn a prop but how fast it is turning also makes a big difference.

 

[cdn-pk]

Re: Evinrude 150 hp prop size

if i were u randy i'd try a 17 pitch.

 

[jimmbo]

Re: Evinrude 150 hp prop size

I ran a 20 RAKER on a 150hp on an 18 ft Glastron and it pulled 5400 rpm. I tried a 22 Raker but it only could manage 4800 rpm. My engine was handicapped at 2500 feet above sea level. That said, to me it sounds like your engine is not quite up to par. A tune up might be needed