whats the rpm drop

[bbc540]

Can anyone tell me how many rpm's you drop or gain changing 1 pitch size in prop running 1.22's in the box thanks sam

[Carnivalride]

Depends on the rpm your currently turning and what pitch you have. Mathematically if you turn 6000rpm with a 16pitch and you drop to a 15p you could see 6400rpm if your engine is still in the power band. Remember prop dia, style and actual pitch all figure into this too.
Here's a ballpark way to figure it: (rpm you turn x pitch)/new pitch = new rpm (6000 x 16)/15 = 6400
Hope this helps,
Loren

[bigkatboat]

NO! Too many factors involved.

[T-Bag]

If all you want is rpm change then why not just change gears. It is a lot cheaper than buying a prop, plus when you start changing pitchs it will increase or decrease tail lift depending on which way you go.