I have heard several opinions on sustained RPM's on diesels. An article in Practical Sailor mentioned running a diesel at 70% of it's rating. I was told by a fellow that had a boatyard, that the Yanmar should be run at 90% of its max rating (3400 max rating for a 2GM20). There was a post in the Cherubini Forum that a fellow said he had taken the Yanmar Engine course and was told to run at max rating for an hour, then back off 100 RPM. How many other ideas are out there? -Doug
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What makes sense?
70% is 2400 rpm. It won't get you anywhere very fast. I have a 2GM20 and at above 31-3200 RPM it starts to smoke a little so it is not running very effiecintly. To me that is the maximum it should be run. 90% sounds about right. Try e-mailing Yanmar.
70% is 2400 rpm. It won't get you anywhere very fast. I have a 2GM20 and at above 31-3200 RPM it starts to smoke a little so it is not running very effiecintly. To me that is the maximum it should be run. 90% sounds about right. Try e-mailing Yanmar.
70-80%
Doug: If you purchase the Yanmar manual, they have some graphs in there too. The optimum power is attained at 70-80% of the Max rating. On the 2GM20F that max is 3600. Some of the engines are rated at only 3400, so you need to determine this rating which is on the front of your engine. Like Don mentioned you rev them too high they actually smoke excessively, which indicates too much fuel which can be caused from other things other than over-reving (fouled prop, fouled bottom, injector problems etc.) The manual is handy and only costs about $40 or so.
Doug: If you purchase the Yanmar manual, they have some graphs in there too. The optimum power is attained at 70-80% of the Max rating. On the 2GM20F that max is 3600. Some of the engines are rated at only 3400, so you need to determine this rating which is on the front of your engine. Like Don mentioned you rev them too high they actually smoke excessively, which indicates too much fuel which can be caused from other things other than over-reving (fouled prop, fouled bottom, injector problems etc.) The manual is handy and only costs about $40 or so.
4JH2E
Yanmars like it hot. I run my 4JH2E at 2800 RPMs for maximum efficiency, but periodically take it up to 3200 just to keep the engine gods happy. My mechanic tells me I ought to take it up to 3400 every now and again. Goodness.
Yanmars like it hot. I run my 4JH2E at 2800 RPMs for maximum efficiency, but periodically take it up to 3200 just to keep the engine gods happy. My mechanic tells me I ought to take it up to 3400 every now and again. Goodness.
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