Tournament 223 top speed

[Redlines]

1982 Tournament 223 powered by a 485, 3.7 185 hp mercruiser. Previous owner stated he could get 40mph as his top speed. Best I can get is 32 mph (half tank of gas and just me at 210 lbs.) The same prop is used(14x19) RPM's at WOT are 4200. Tried several different performance props but actually got lower rpm's and top speed. Dropped to a 17 pitch and, just as I thought, rpm's went up 100 and top end speed went down 1 mph or so. This engine has 155 lbs of compression in each cylinder and seems like it wants to give more but doesn't. So, whose top speed is more likely to be more accurate, his at 40mph or mine at 32mph. Oh, both were done with GPS. Thanks!

 

[DennisG01]

Couple questions...

-- Are you trimming up as much as you can... just before it ventilates?
-- What's the bottom condition?
-- Going back that old, I do not know the "spec" for WOT RPM - newer ones are 4800 - do you happen to know the spec for your engine? Sometimes, if it's not too faded, it may be printed right on the flame arrestor cover or one of the valve covers.

Only getting another 100RPM's out of 2" of pitch sounds light.

Compression is good. Might want to do a leak down test, though.

 

[Redlines]

I've experimented quite a bit with the trim. Boat bottom is clean, no growth. Engine specs are 4200-4600 RPM @ WOT. I thought for sure when I dropped down to a 17 pitch that my rpm's would go up more than it did! I'll try an infrared meter for rpms. Heck, maybe it's the tach, and 32 mph is it. It is a heavy boat but when PO said 40 mph I was really hoping he was not pulling my leg. Maybe timing should be advanced a bit. Guess it'l have to wait til Spring.

 

[suzukidave]

i can't see how you'd ever get 40 mph out of a 4 cylinder i/o on a 22' boat. that engine is making well under 200hp even in perfect order. our 1982 deep v 19' could not make 40 mph with a carbed v6 volvo.