Re: Is hitting the rev limiter ok?
You will not hurt the engine by running it up against the limiter. That's why it's there. (It's electronic)
It may be telling you that you could go up a couple of inches in prop pitch and still get good performance.
If you get a WOT rpm near the max you'll have a good holeshot for pulling skiers etc.
The boat should be propped so that the RPM is inside the range suggested by Merc
Go
HERE to calculate what you have right now. You'll need to know your speed accurately (GPS or RADAR) and your drive ratio.
Run the boat up to max speed and plug in the numbers. You'll find prop slip at WOT. you can also find theoretical speed (with no slip) but it's sort of meaningless since no boat can go theoretical speed.
The same calculator will calculate your actual slip which you can use to estimate what your speed will be with a different pitch prop.
Most runabouts with a single prop have a slip in the neighborhood of 10-15% slip (My FourWinns calculated at 11% slip ...4200rpm, 1.43 ratio, 50 mph)
At 60mph, 5100rpm it was about 12% (It had a rev limiter.....ME!)
This was of course with the other engine I had (OMC King Cobra 460)
People I have talked to using the Bravo III indicate that the slip will be somewhere around 6-8% This makes sense due to the better "bite" with counter rotating props.
Cheers,
Rick
I have a 2001 5.7L Mercruiser EFI w/ Alpha I Gen II outdrive. The manual says the max RPM should be from 4400 - 4800 RPM. I was talking to Mercruiser technical support one time and he indicated that the rev limiter is set ~150 RPM above that or 4950. He indicated that he didn't mind going down the lake bumping into the rev limiter (i.e. max RPM)... Will bumping into the rev limiter cause any damage to the engine or does it just mean you could be running a slightly steeper prop?
Thanks- Dshow
