What should Cougar top speed be?

[angle iron]

You're speaking a foreign language to me!

I am the second owner of the boat. The original owner repowered it. He had a 26 Fury, and it wouldn't hit max RPM for the motor. I put a 24 Fury and still can't get the max RPM. I can't get it past 5900.

If I pick up another 300rpm, how much top end speed would I realistically pick up? (ballpark guess)


I'm not sure if I need to work with my local prop guy (we have a good one in the area), or I I need to have my local Mercury service center check it out.

He's saying your throttle might need adjustment to reach WOT. Check with mechaninc.

[fishnfireman]

You're speaking a foreign language to me!
I am the second owner of the boat. The original owner repowered it. He had a 26 Fury, and it wouldn't hit max RPM for the motor. I put a 24 Fury and still can't get the max RPM. I can't get it past 5900.
If I pick up another 300rpm, how much top end speed would I realistically pick up? (ballpark guess)
I'm not sure if I need to work with my local prop guy (we have a good one in the area), or I I need to have my local Mercury service center check it out.

I would suggest the service center first.
Best I can explain, these motors use a mechanical shift and throttle cable from the boat to the motor but the actual throttle movement is digital or (fly by wire) if that makes sense. You can't see the throttle body open. So the only way to know if its opening 100% is with a Mercury laptop while cycling the hotfoot. Something that evidently not all mechanics are versed at.. First one I called had no idea what I was talking about.
I bought a used 250R that was set with a different boat/hot foot. Long story short motor would not turn much over 5800 rpm. When I got it hooked up it was only putting out 90%...to get 100% we had to remove the pedal stop on the hot foot after adjusting the motor linkage as far as it would go.

Another 300 rpm on a 24 Fury can be figured using the Mercury prop calculator.. Some claim the Fury is a stiff prop and the 24 should be figured at 24.7

With 1.75 gears a 24.7 pitch prop turning 5900rpm with 6% slip which is 2 percent less than what BCB said they did on there Eyra tests with Mercury figures out to 74mph.
the same gears and prop but turning 6200rpm with 6% slip = 78mph --- so you should see about 4mph with 300 more rpm..
https://www.mercuryracing.com/prop-slip-calculator/

[Cajunhunter67]

As mentioned above. One of the issues that will be missed occasionally by a mechanic during a repower is the Hotfoot throttle stop hitting PRIOR to the engine hitting its wide open throttle stop.
Keep in mind the new V8 4 strokes run at a higher redline. The prop usually supplied is a 24 Fury 3. The one you have now. A 26 pitch would have been much to tall.
Your still lacking 300-400 RPM's. Altitude, load and Engine height can all play a part in limiting top end RPM's.
The easiest to eliminate is the Hot foot stop. I'm not familiar with the new V8's. It may have to be checked by a mechanic. On the 2 strokes you can visually check the WOT stop on the engine. I had a hotfoot that was topping WOT throttle on my engine. Makes a big difference.