Diesel crusing rpm's

[ljcraigie]

I have a new to me Hunter 280 with a 18 HP Yanmar. There was nothing in the owners manual or the Yanmar manual about optimum engine speeds. It says idle is around 750 RPMs and to run at 2500 RPMs to burn excess carbon out after prolonged idling. But are there boundaries on what crusing motor speeds should be?

 

[petersea]

cruise around 2600 to 2800, max rpm 3600 but should not be at max for long durations

 

[Sailgunner]

I run at 2800 with my current and last Yanmar.

 

[Saillife]

I've always heard that you should run at ~80% of max RPM. Diesels like/want to be run.

 

[Steve Dion]

http://yanmarhelp.com/operate.htm

about 85% of max rated RPM. They may burn a little more fuel, but they will last longer at these engine speeds.

 

[John T1594]

Engine tag

All of the above posts are correct. You can see the manufacturer's recommendation on the engine ID tag - usuallly mounted on the front of the engine. It usually has information about Max and continuous RPM recommendations as well as oil weight.

 

[ljcraigie]

Thanks to all for responding. Hopefully I can find the engine tag with specifications.

 

[Steve Dion]

Tag is on the front of the engine. The GM max RPM is 3600.

 

[Tally Ho]

I have a '96 Hunter 280 with the 18hp Yanmar. I typically run mine at ~3000 RPM's. Pushes the boat at around 6kts. Motored 75+ miles over 2 days back in April when I brought it down from Milwaukee where I bought it. She just ran and ran and ran (and on 1/2 tank of fuel).