Prop on Four Winns 200

[triscadek209]

Ok well here's another one for you guys...
I have a 1990 Four Winns 200 Horizon, 5.7L Cobra weighing in at 3,200lbs I purchased a short time ago. I recently had to change my outdrive and for cost reasons went with a 4.3L stern which changed my drive ratio from 21/16 to 21/19.
Before the swap I was able to run 42mph (not WOT) at around 4000 rpm (cruising speed) with a 17" 3 blade. Aluminum. Great holeshot also. I was never able to test for WOT yet as the upper unit failed (due to my incopetence) suddenly during the seasons first test run. Undoubtably it put a huge smile on my face, great speed with plenty in reserve, just sad I never got to see it before it locked up. :-/

Now, with the new gearing in the new drive and with a 19" 4 blade, I'm running 4600 rpm @ 42 MPH WOT :-( with this being an older motor and by listening to the motor I'm most comfortable runnin her around 3600 rpm or lower to be easy on her for cruising speeds and that's only around 33mph. I'm okay with running WOT for short periods of time, just not all the way across the lake unless it's an emergency. Would rather have a cruise speed closer to, if no at 40 mph and top speed at or near 50 mph.

The hole shot was pretty decent with 4 adults, 30 gallons of fuel and a cooler aboard. I will keep the 4 blade 19p for watersports etc however I want more top speed and a higher cruising speed for leisurely cruises. I'm thinking a 23p 3 blade will have me right on the money or no? Do I want a 4 blade 23p going that high in pitch to help with holeshot still?

I only want to buy aluminum for possible danger to the lower unit as I will be traveling to several lakes and a couple I'm unfamiliar to.

 

[steelespike]

Re: Prop on Four Winns 200

First of all You don't want to force your motor to a lower rpm with a prop.
In the long run your motor will be happier to rev freely within its rpm range and use the throttle to select an rpm you feel works.
A marine motor is working very hard;like a car pulling a trailer up a never ending hill. Increasing pitch is like putting it in overdrive
making it even harder.
As you increase pitch you are making the motor work harder. A 23" pitch will lower rpm about 600.Taking you completely out of the range.If the final drive ratio is 1.61 your 42 at 4600 produces about 18% slip a little high. If we use about 1.84 ratio slip is a low 8%.
Possible but unlikely.Is the speed by gps?
It does seem a 5.7 could windup more though we don't know for sure where the ratio is.Common 4.3 numbers I find are 1.61 and 1.84.assuming your numbers are accurate going to a 19" 3 blade should increase rpm and might add a little speed without making it harder for the motor.Increasing pitch will further slow hole shot a 21" prop could lower rpm 300 to 400.Further dampening performance.

 

[triscadek209]

Re: Prop on Four Winns 200

Yes, all speeds were by GPS. Recommended RPMS were a max of 4600 and a low of like 4200. The motor has plenty of power I believe to muscle out of the water, ESPECIALLY with the new gear ratio. I'm mainly looking for more top speed. However, I don't want to have to swap gears unless it's an absolute must. I just bought the boat, found out it was pretty darn fast got excited then BOOM! Seizes bearings, V6 drive goes in and will never be fast again. (Don't wanna have a $10k, $3k boat)

 

[steelespike]

Re: Prop on Four Winns 200

The 4 blade usually helps hole shot but will be slower. As I suggested a 3 blade 19 should add 100 to 200 rpm and a little speed.
Increasing pitch to 20 or 21 might add more speed at the sacrifice of slower hole shot.
With your situation you need to find a dealer that will let you try props with the understanding you are buying.Usually
requires a deposit.
The final drive on a 5.7 is 1.51 to 1, A 4.3 is 1.66. Should have amazing hole shot but may run out of prop.
I wonder if there is a mismatch between the final gears and the intermediate gears.
Your motor is stumped by only a 19" prop.
You can check the final ratio by manually turning the motor and counting the revolutions to one revolution of the prop.