more top end ?

[canman]

hi everyone , i have a 16 foot larson senza with a 140 johnson with a hustler 17 inch pitch at 6000 rpm . i would like to go to a hustler 21 inch pitch to see if i can get a bit more top end out of it . i am thinking this is going to drop my rpms to low at wot . does anyone out there run a 21 inch pitch on a 16 foot boat and a 140 on it ? i am just curious to know what there wot rpms are . thanks ..

 

[trendsetter240]

Re: more top end ?

hi everyone , i have a 16 foot larson senza with a 140 johnson with a hustler 17 inch pitch at 6000 rpm . i would like to go to a hustler 21 inch pitch to see if i can get a bit more top end out of it . i am thinking this is going to drop my rpms to low at wot . does anyone out there run a 21 inch pitch on a 16 foot boat and a 140 on it ? i am just curious to know what there wot rpms are . thanks ..

You can usually expect a 200RPM drop for each inch of pitch you add. In this case a 21p prop would put you around 5200RPM at WOT.

If this is in the recommended WOT range for your motor then you should be good to go.

 

[Dhadley]

Re: more top end ?

Let's look at a few things. What year 140? How's your set up?

A 17 on a 140 on a 16' boat does seem a little on the low side.

 

[kenmyfam]

Re: more top end ?

I use a 19" pitch on my 1985 140HP Looper (uncupped) on a Doral 164. Gets me 5,800 RPM at WOT.

 

[canman]

Re: more top end ?

I use a 19" pitch on my 1985 140HP Looper (uncupped) on a Doral 164. Gets me 5,800 RPM at WOT.

motor is a 1990 fresh rebuilt , motor is set good , was water tested to make sure motor was set at the right height.

 

[Dhadley]

Re: more top end ?

OK, the motor is a looper. The next step would be to post a pic of the lower unit with the AV plate parallel to the keel so we can see the set up.

 

[steelespike]

Re: more top end ?

If your not experiencing any ventilation(cavitation) now you may be able to raise the motor a hole or two.The Hustler will allow more height than some other props.Could gain some speed just by raising the motor.When your sure it is at its max height I think a 19' would be a better choice.Best to stick withg the same brand to make improvement more predictable.

 

[canman]

Re: more top end ?

hi everyone . i tried raising the motor one hole and the motor starts to cavatate . i dont have a camera , what i will do is wait for spring and try a 19 pitch , the boat has been put away till spring . thanks .

 

[steelespike]

Re: more top end ?

Yes sounds like the setup was pretty close in the first place.
Nothing ventured nothing gained.