how to know what prop

[powerstroker]

my engine has i have a 1971 100 evinrude model number 100193. i want to know what prop i got. and i also wanna know how to gear it up? do i just change the prop or what?

 

[Randybeall]

Re: how to know what prop

I would suggest you go to props and prop questions. The first sticky will tell you what you need to know in the prop information. Then post your question with the required information. At this point we don't know enough to make an educated guess.

 

[hidef]

Re: how to know what prop

The following is generally what happens.

Every 2 " inch change in pitch will change your RPMs by 300 as long as the prop material and the construction is the same. If you have a 15" aluminum 3 blade prop and your engine is turning 6100 RPM going to a 17" aluminum 3 blade prop will reduce your RPM to 5800.

Going from Aluminum to Stainless will decrease you RPM by 200 if the pitch stays the same. Changing pitch add or decrease 300 RPM for every 2" plus the 200 for material change. So a change from an Aluminum 15" prop at 6100 to a stainless 17" will decrease your RPM to 5600.

Going to a 4 blade from a three blade will decrease the RPM by 100.