Volvo MD7A speed

[John Dupras]

Hi all - just a question. I have a Cape Dory Intrepid 9M with a Volvo MD7A (raw water cooled). When running, what is the recommended RPM? I have read that diesels shoud be run at higher RPM's to avoid corboning up. Just what does "higher" mean? I currently run at about 1800-2000 when motoring. Any information would be appreciated. Thanks.

John
S/V Mariah



jdupras@aetea.com

[Robert]

Hi all - just a question. I have a Cape Dory Intrepid 9M with a Volvo MD7A (raw water cooled). When running, what is the recommended RPM? I have read that diesels shoud be run at higher RPM's to avoid corboning up. Just what does "higher" mean? I currently run at about 1800-2000 when motoring. Any information would be appreciated. Thanks.

John
S/V Mariah

I recently bought a '79 CD28 with a Volvo MD7A. The engine mechanic who did some surveyor-recommended work---and who is Swedish---said that 1800 rpm would be a good relaxed cruising speed and would use about one quart of diesel per hour at this rpm. The manual gives 2600 rpm as max speed. A friend who has extensive experience with diesel engines says that, unlike gasoline engines which have an optimum rpm considerably lower than their maximum rpm (redline on the tach), diesel engines' optimum, most efficient rpm is the same as their maximum rpm. On one leg of the trip down the intracostal from Houston to Port Isabel TX, 1800 rpm would no longer maintain headway into considerable wind and waves, so I went to 2200 rpm for over 7 hours without incident. The Volvo seemed quite happy at that rpm, although fuel consumption went up slightly.



rbtfsh@utb1.utb.edu

[John Dupras]

Hi all - just a question. I have a Cape Dory Intrepid 9M with a Volvo MD7A (raw water cooled). When running, what is the recommended RPM? I have read that diesels shoud be run at higher RPM's to avoid corboning up. Just what does "higher" mean? I currently run at about 1800-2000 when motoring. Any information would be appreciated. Thanks.

John
S/V Mariah

I recently bought a '79 CD28 with a Volvo MD7A. The engine mechanic who did some surveyor-recommended work---and who is Swedish---said that 1800 rpm would be a good relaxed cruising speed and would use about one quart of diesel per hour at this rpm. The manual gives 2600 rpm as max speed. A friend who has extensive experience with diesel engines says that, unlike gasoline engines which have an optimum rpm considerably lower than their maximum rpm (redline on the tach), diesel engines' optimum, most efficient rpm is the same as their maximum rpm. On one leg of the trip down the intracostal from Houston to Port Isabel TX, 1800 rpm would no longer maintain headway into considerable wind and waves, so I went to 2200 rpm for over 7 hours without incident. The Volvo seemed quite happy at that rpm, although fuel consumption went up slightly.

Thanks Robert - I feel better now
John



jdupras@aetea.com

[joe brown]

Hi: ( I posted this first on the wrong message, now:) I also have a Volvo MD-7A in my boat but cannot get it to rev higher than about 2200 rpm. I'd like to rev it up to the
maximum (manual) 2600 rpm to blow out carbon for short periods occasionally. I have a 3-bladed prop which may be part of
the reason or perhaps my tach doesn't read correctly. Thoughts would be appreciated. Thanks.

[Jeff Schmoyer]

Not the same engine, but similar...My CD 27 came with just a little idiot light panel, and no tachometer. So I have no idea how fast the lil' beast is turning.

Has anyone retrofitted a tach to this engine. Was it hard? Source for parts? Cost?

Best Regards,

Jeff



Jeff. Schmoyer@IFF.COM