On Mon, 07 Jun 2004 07:28:56 -0700, James Gemmill gemmilljim@hotmail,com wrote:

According to my local service men I should be able to turn about 4600
RPMs with my 5.0 liter mercruiser. I am only turning 4200 at full
throttle, on plane and empty except for drive and one passenger. My
service guys say I can burn the valves at this rate.

What say you all?

Elevation of test, about 4000 feet above sea level, 5.0 liter Cobalt
21 foot open bow, 450 hours on engine.

Thanks in advance for any helpful info.

Hi.

All is OK.

Consult your engine performance table or specifications and you will find out that EVERY combustion engine LOSSES 1 % of
it Power every 100 meter above sea level. (about 1% every 330 feet asl.

So you power lost will be around 12 % equivalent to 450-550 RPM at 4,000 feet asl.

Consider else "Tacho error" varying from 8-to 10 % more or less.

There is nothing to do to increase power back to Sea level task.

You could increase performance to original increasing of the same ratio air intake (Turbo) or Gasoline Ottans (or N2O)
or Carburetor Yet (+ 10% bore) or increasing Exhaust pipelines and Silencers...

Else a less "fine" Air Filter" (or no filter of all) could increase performance (no dust there... I suppose...).

Else Temperature decreases Power 1 % every 4°C less than 20 °C.

Suggestion is to put intake over the muffler just to have hot air intake.

Not sure but else the weight of the Floater inside Carb could be varying the Gasoline supply.

A more fluid Oil has to be used both inside Engine than inside Gearbox, or your power will be wasted to turn "glued"
gears.

Else a propeller with a 10 % less pitch could be useful.

....and this is only "some" things to verify for...

You could else remove the Alternator Belt and spare some HP in this way...

Good Luck.


WinXP