prop selection for WOT

fishstu · #1 08-29-2005, 07:09 PM

My 20ft MA with a 2001 Merc 150 EFI outboard has a SS Mercury Laser II 19 inch pitch prop. In most conditions the engine at WOT will not go over 5000 rpm. Otherwise the prformance is fine. The WOT rpm should be 5500.
I would like to hear from folks with the same hull/engine set up which props they have and what is the WOT performance. Also any advice on an other prop selectiopn is welcombe.
I have been told to try a 17 inch version of the same prop.

RS · #2 08-30-2005, 11:21 AM

Quote:

The WOT rpm should be 5500.

Do you mean that the max rpm is 5500? If so, and as long as your hole shot and other performance is good, I'd leave well enough alone. Chances are that by dropping the pitch you'll just get a bit better acceleration and no noticable change in the top end.

SECF3114M73J · #3 08-30-2005, 11:59 AM

Your motor will last longer and you'll get better fuel economy if you prop your motor to turn close to the 5500 r.p.m. upper limit . You're lugging your motor, it's like driving your car in second gear.

fishstu · #4 08-30-2005, 01:42 PM

Thanks for the feed back guys.

Hole shot and general performance is good. Acceleration is good, the motor does not seem to be lugging, but the WOT stops at 5000 rpm. Now I wonder if the throttle cable could be adjusted to get more rpm? I feel it would be better for the Engine to be able to rev to recommended spec.

Bigshrimpin · #5 08-30-2005, 05:47 PM

Fish - You definitely need to get the RPM's up. Everything I've read about those engines says to prop that motor above 5500. NoBones and R.NAHIM have run the 19 pitch laser on there 200 mercs and switched back a 17 Mirage. Unfortunately Merc doesn't make a 17 pitch Laser II.

Fr. Frank (who used to run test boats for wellcraft) is running a Large Diameter 16 pitch powertech prop on his 150.
Both the mirage and the Powertech are real nice . . . if you have the $$$.

http://www.mercurymarine.com/props

http://www.ptprop.com/catalog/

Personally 45mph in my 20MA is about the max for my comfort level; However, if you wanted to get your RPM's the hard way, you might look into 2.0L mods on screamandfly or ByuBoyz. There are lots of mods that can be made to push the 2.0L merc well over 200hp.

www.byuboyz.com
www.screamandfly.com

SECF3114M73J · #6 09-01-2005, 02:04 PM

By lugging the motor,I meant that you're working it to hard.

jorgeinmiami · #7 09-02-2005, 09:05 PM

On a 1971 20 cc with a 1998 200 merc EFI... what are others running?

I have a mirage plus 17" pitch?

sailcat · #8 09-14-2005, 10:24 AM

On my 72 20' CC T-top with a 200 Johnson, 17x19 SS, I'm turning 5700 to 5800 WOT and 51 mph. The hole shot is incredible.

Abe's Rocket · #9 09-14-2005, 11:56 AM

i have a 235 OMC on my 20 and the hole shot sucks...need to get a new wheel i guess.

NoBones · #10 09-14-2005, 01:38 PM

My 1970 20SF has a 97 Carbed 200HP Merc. 21 inch LaserII
prop. 24 inch Bennett tabs and 80 gallon tank. By myself
the hole shot and top end is great. Top speed 62mph on the
GPS at 5800rpm. (My engine has been tricked out) If I put three of my 250lb buddies in the boat, hole shot and top speed drops off real bad. Solution: 4 blade prop for those times when I run a heavy load. Top speed is around 55mph 5800 rpm(with 4 big guys in the boat) But my hole shot is far better, not quite as good with the 3 blade by myself, but it works. Hope this helps.
See ya, Ken