2014 SX240 Power loss at elevation. Re-pitch or new Impeller for power gains. 6000-8500 FT elevation average.

[dtnorc1]

Does anyone have experience with high elevation power loss and recovery? Dealership in Denver wants $450 to re pitch props. I am not sure what kind of power delivery it will return. Any advice is appreciated.

 

[buckbuck]

@J-RAD Aren't you up in the mountains?

 

[Canuckjetboater]

Does anyone have experience with high elevation power loss and recovery? Dealership in Denver wants $450 to re pitch props. I am not sure what kind of power delivery it will return. Any advice is appreciated.

@dtnorc1 .....changing the pitch of props or the gear ratio of outdrives in an I/O have been common cures for high altitude power loss. Modern MFI systems and ECMs can help a bit and you may be able to re-flash your ECM, if not sounds like your dealer has a suggestion.

 

[J-RAD]

@J-RAD Aren't you up in the mountains?

Yep! From Utah here. I run on lakes from 4500' to 7000' elevation. I did a full impeller swap and pitch for elevation. It made a huge difference for me. I went from 6800 max RPM to 7500 and improved performance all around. Your 195 has a larger 160mm impeller, but pitching it properly can make a good difference. You might want to check with your dealer on that price though. I've heard many here mention how Yamaha will cover the cost of pitching for altitude on their impellers 1 time on new boats.

The next best way to pick up a few extra missing RPM is the ribbon delete. It's pretty useless on these fuel injected boats anyway and only there due to outdated laws in several states still requiring them. Just get a spark arresting filter if you're concerned.

 

[dtnorc1]

Thank you!

 

[OrangeTJ]

Keep in mind that there is no way to regain the "power" that is lost at altitude. There is just less available as there is less oxygen to mix with your fuel. The ecm compensates by reducing the fuel such that it is well matched to the available oxygen but with both being less, less power is the outcome. You can, however, make more effective use of the power your engines can produce at altitude through appropriate changes to pitch of impellers or props.

 

[J-RAD]

Keep in mind that there is no way to regain the "power" that is lost at altitude. There is just less available as there is less oxygen to mix with your fuel. The ecm compensates by reducing the fuel such that it is well matched to the available oxygen but with both being less, less power is the outcome. You can, however, make more effective use of the power your engines can produce at altitude through appropriate changes to pitch of impellers or props.

Things like maximizing free air flow via the ribbon delete does help regain some lost RPM/power. Like you said, it's making use of what's available.

 

[OrangeTJ]

Yes, sorry. I should have said that there's no way to regain power via repitching the impellers. Obviously you can modify the engines themselves via things like ribbon delete or all the way up to supercharging (not sure I've seen anybody go quite that far!) but those mods, too, will produce more power at lower density altitude than they do at high altitude.