pitch question

N

newowner1

Recruit
Joined
Sep 2, 2008
Messages
5
If I have my prop pithed for 4400 ft elevation, how would it run in a lake at 600 ft elevation if at all?
 
Ross J

Ross J

Lieutenant Junior Grade
Joined
Nov 30, 2001
Messages
1,119
Re: pitch question

A prop pitched to work at optimum efficency at 4400ft is set to utilise the power output from the motor. At 4400ft the air is thiner with less oxygen than at sealevel therefore the engine would have the fuel air mixture adjusted and the pitch chosen most likely would be a slight decrease from sea level. For instance if you ran a 19in pitch at 4400ft then you would most proberly run a 21in at sea level, so at 600ft the choise might be to stay with 21in.
If in doubt stay with the one chosen to perform at 4400ft since it will obviously work but may use a bit more fuel for the same job.
Ross
 
D

drivehard

Seaman Apprentice
Joined
Jun 2, 2007
Messages
47
Re: pitch question

assuming both locations are at 80 degrees F, it looks like you will have 1.18 times more power at 600 ft than you will at 4400.
 
Randybeall

Randybeall

Petty Officer 1st Class
Joined
May 2, 2008
Messages
319
Re: pitch question

Of more concern is the drop in altitude will offer increased air density which will lean out the mixture. You may need to increase jet sizes to keep from running too lean and damaging the pistons. Of course if you have fuel injection it will likely self adjust for altitude and that is no problem. You will gain power and may find that you can increase the pitch of the prop but that will need to be determined after a WOT run. If it goes beyond the recommended peak rpm increase pitch.
 
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