Factory WOT is spec'd at 4,800 rpm. I don't think 5,000 for a short burst would hurt too much (how accurate is your tachometer ?) My 4.3 ran up to 5,200 without harm but, it is fresh and has roller rockers.
Was your 57mph read on a GPS? Seems to me like your boat is already dialed in pretty well. By my calculator using your numbers (assuming the standard V6 Merc 1.84 gears); you are running less than 5% slip on your prop.
Even if it is not a GPS speed and the tach is off a touch your boat is running quick (with 540lbs). Nice.
23 |
x |
5,000 |
= |
115,000.00 |
= |
59.2 |
|
0.95 |
|
56.2 |
1.84 |
x |
1,056 |
1,943.04 |
|
|
Sean Conroy,
1964 Formula Jr. (hull #2) project
1972 Greavette Sunflash III
1981 Kavalk Mistral project
"A man can accomplish anything... as long as he doesn't care who gets the credit."