Prop Selection on evinrude 140 V4 looking for advice

[85evinrude140]

I have a 1985 Ranger 340V with 85 Evinrude V4 140 with hydraclic jack plate and proped with SS renegade 4 blade 13 1/2 diameter 23 pitch prop, turning 6000 RPM's 2 people 1/2 tank fuel moderate load 3 batteries GPS 48. I have read that the 340 hull is a quick little hull due to being short 17ft and 88 inches wide and was thinking 48 at WOT turning 6K RPM's is a little slow. Does have hydrafoil which it jumps on plane quick did however remove hydrafoil to see how it reacted and took forever to get on plane so put hydrafoil back on. Looking for advice as to what direction I need to go , have experimented with motor height and doesn't seem to help in top end speed. I feel if I go with more pitch in prop to achieve lower RPM's that my hole shot is going to suffer.

 

[Frank Acampora]

If you go to higher pitch and still want to hole shot buy a vented prop with various sized plugs. That way you can easily experiment with what size vent hole is optimum for your rig.

 

[steelespike]

Using a 1.86 gear ratio the prop calculator indicates your slip is 31%,very very high.
With the speed by gps many times high slip indicates the tach is in error high.Could be set wrong
or just old.Slip on a boat like yours would usually be in the low single digits.10 or 12%
Perhaps you could borrow a shop tach to verify your rpm numbers.We need to know before we can go farther.
Your unassisted sluggish hole shot could indicate your over propped.Or the motor is tired.
Sometimes a prop with a lot of bow lift may not do well out of the hole. I don't know where the Renegade fits.
I would think a 23" 4 blade ss prop would have good numbers.
Did you record the top speed without the foil?

 

[85evinrude140]

Thanks guys, I will see about getting another tach and verify if my existing tach is giving correct reading, I did not gps speed without hydrofoil but I do know without foil once bow came down boat rocket to max speed and handled a lot better. I will repost results of tach outcome once I get time to test.

 

[walleyehed]

Using a 1.86 gear ratio the prop calculator indicates your slip is 31%,very very high.
With the speed by gps many times high slip indicates the tach is in error high.Could be set wrong
or just old.Slip on a boat like yours would usually be in the low single digits.10 or 12%
Perhaps you could borrow a shop tach to verify your rpm numbers.We need to know before we can go farther.
Your unassisted sluggish hole shot could indicate your over propped.Or the motor is tired.
Sometimes a prop with a lot of bow lift may not do well out of the hole. I don't know where the Renegade fits.
I would think a 23" 4 blade ss prop would have good numbers.
Did you record the top speed without the foil?

Steelespike, the 140 Bigblock 20" V4 is a 2:1 LU..

 

[steelespike]

Thanks
​Numbers still come out high 26% slip.Considering the prop,and the boat a tach error on the high side seems likely.
I suppose if the motor is too high it might be venting as little.