Prop Question

carbineone

Petty Officer 1st Class
Joined
Feb 11, 2010
Messages
268
These two props are for my Johnson Outboard.The one on the left has no markings as to pitch or anything and the one on the right is a 10 3/4 x 11.My question is the two are definitley differant blade configurations for sure but any guess on the pitch on the left one and which would likely do what as far as performance.I am experienting with some differant props and would like to know if the one on the left would be a good prop as far as going fast or maybe a good hole shot.In other words how will each perform compared to each other.The one on the left definitley has broader blades and thats all I know for sure...Thanks
 

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Bifflefan

Commander
Joined
May 27, 2009
Messages
2,933
Re: Prop Question

The best answer is one you have after you try it.
 

carbineone

Petty Officer 1st Class
Joined
Feb 11, 2010
Messages
268
Re: Prop Question

Yes that would be the case probably.I have ran the one on the right yesterday but just wanting to know what I might expect from the one on the left.I do not have a speedo so maybe I will just start imagining what the differance is if I do not know.LOL
 

carbineone

Petty Officer 1st Class
Joined
Feb 11, 2010
Messages
268
Re: Prop Question

Oh since the one on the left is not marked does it appear to be a higher number pitch than the one on the right?
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Prop Question

What you really need is a tach. Those two props are totally different designs. The one on the left has large, uniform blade area and is typical of an all around everyday, utility prop found on lots of small outboards. The one on the right is more of a performance prop. Can't tell by the picture which has more pitch but that is of little significance since prop design dictates how it performs compared to another design. Two props of the same pitch can perform very differently. The best prop for any engine is one that allows the engine to rev at the upper end of the manufacturers wide open throttle rpm band with what you consider an average load. What you see on the tach at WOT should be what the manufacturers recommended max is.
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: Prop Question

As suggested you really need a tach and a gps to select the best prop.
A tiny tach is about $40 and if ,for the motor in your avitar, will fit any 2 cylinder 2 stroke.Its important for both your motors health and best performance to have the max rpm and speed.A prop shop can measure your prop for you.
 

carbineone

Petty Officer 1st Class
Joined
Feb 11, 2010
Messages
268
Re: Prop Question

Thanks,I have a little digital tachometer that used to be on one of my kids go carts that had a 6 HP Briggs & Scrapiron engine on it.Would that type of tach work?If so where do you hook to in the old Johnson?I know where to hook them up in the older cars.My HP is rated at 4500 RPMs and the operating range is from 4000 to 5000 RPM.So are you saying whichever prop I have on there it should operate in that range when WOT? Thanks
 
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