31.8 CI Evinrude 25/30hp RPM range discussion discussion

[captbone]

Hello,

I hope all is well. I am back again for more insight.

I am currently running a 2001 Johnson 25hp Johnson on a heavy boat. I have installed the 30hp Carb from similar year and it runs great. I have installed a tiny tach so I know what I am spinning. My question is what RPM range should I be in?

The 25hp RPM range is 4500-5500 With peak power at 5000
The 30hp RPM range is 5200-5800 With peak power at 5500 (all of this per the manual).

I currently have three SS props.

3 Blade 10.5 x 11 SST that turns 5200
3 Blade 10.75 x 10 SOLAR Saturn that turns 6100 in rev limiter
4 Blade 10 x 11 BRP SS that turn 4800


I plan on having some cup added to the 10 pitch SOLAR to hopefully bring RPM down to 5700-5800. All props run within 2 mph of each other (21mph) and I like each for their own reasons.

What should I target for my RPM range since it technically is a 25hp? But then again the 30hp is the same just with the carb so technically I have a 30hp?

Also how do your remove the rev limiter in the powerpack? When racing these engine in the GT class, how fast do you spin them up to and where is the sweat spot.

Thank you for your time and insight.

[Chairman]

I have raced up to the mid-6000s or so. You will need a different pack to get rid of the limiter. Look for one that does NOT have the number 6100 printed on it.

[captbone]

Thank you for the reply. What RPM would you normally shoot for when racing? 5500 seems to be the sweet the spot thus far. The engine sounds different with the 10 pitch on it and seems happier. I would not image propping a 25hp at 4800 at WOT.

[Chairman]

I shoot for the 6000 to 6500 range.