I have a '95 Beneteau 321 with a Perkins M30. Can anyone tell me what the max sustained rpm's the engine can run at. When i go over 2000 (2200-2400 i start getting some grey smoke) Thanks, John Perri
What's max continuous running rpm on perkins m30
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At what load? The faster you turn the prop
the more HP you are using. Most engines are rated for pleasure boat service. Which has a much higher HP rating than work boat service. If you are blowing smoke then throttle back a little. The engine isn't delivering what you demand.
the more HP you are using. Most engines are rated for pleasure boat service. Which has a much higher HP rating than work boat service. If you are blowing smoke then throttle back a little. The engine isn't delivering what you demand.
Perkins M 108
John, My 1990 boat has a slightly tired Perkins 50HP M-108. It will run all day at 1,800 RPM with a little blue smoke due to a worn #1 cylinder. And minimal oil consumption. When I run it at 2,200 RPM I get black smoke and no more speed. So needless to say, I run it at 1,800 and have an extra beer. Ross is right on. Peter
John, My 1990 boat has a slightly tired Perkins 50HP M-108. It will run all day at 1,800 RPM with a little blue smoke due to a worn #1 cylinder. And minimal oil consumption. When I run it at 2,200 RPM I get black smoke and no more speed. So needless to say, I run it at 1,800 and have an extra beer. Ross is right on. Peter
perkins speed
The m-30 should be able to run around 27 or 2800 all day. I had some problems with mine and it turned out that my exhaust riser was plugged. The mechanics keep telling you to run them harder to keep them happy. RG. Pretender.#197
The m-30 should be able to run around 27 or 2800 all day. I had some problems with mine and it turned out that my exhaust riser was plugged. The mechanics keep telling you to run them harder to keep them happy. RG. Pretender.#197
If you're getting black smoke a low RPM
(2200 - 2400 RPM is VERY low), You have the wrong prop. That causes the motor to put out partially unburned fuel, and that's black (Watch a diesel truck or bus start up from a dead stop). Either a prop of the wrong diameter or pitch will cause this. Gray smoke (are you sure that it's not white?) is from burning crankcase oil. That's bad, and usually indicates a leak around the piston rings. White smoke is from insufficient cooling of the exhaust due (most likely) to insufficient water through the engine (check your heat exchanger and water pump). As Pretender stated, your engine should be able to run at 75 - 80% of Wide Open Throttle (WOT) all it's life and be happy as a clam, and your boat should be running at hull speed at this RPM. Steve Alchemist C-320
(2200 - 2400 RPM is VERY low), You have the wrong prop. That causes the motor to put out partially unburned fuel, and that's black (Watch a diesel truck or bus start up from a dead stop). Either a prop of the wrong diameter or pitch will cause this. Gray smoke (are you sure that it's not white?) is from burning crankcase oil. That's bad, and usually indicates a leak around the piston rings. White smoke is from insufficient cooling of the exhaust due (most likely) to insufficient water through the engine (check your heat exchanger and water pump). As Pretender stated, your engine should be able to run at 75 - 80% of Wide Open Throttle (WOT) all it's life and be happy as a clam, and your boat should be running at hull speed at this RPM. Steve Alchemist C-320
Determine the engine ratings
John: Determine the engine ratings. Most of the modern diesels run at higher RPM's than the older ones. The other thing that they have in common is they are normally designed to run at 70-80% of the max rating. If you engine is rated at 3600 rpms then you would be looking at 2500-3000 rpms. We already know that you a pumping out gray/black smoke at these rpms, so you can start with the prop to be sure that it is not fouled or something wrapped around the shaft. The mixing elbow on the Yanmar's when cooled by salt water are notorious for clogging up. This is usually not a terrible thing to try to diagnosis yourself. You just need to remove the exhaust manifold and elbow. Then inspect where the cooling water and the exhaust come together. This gets Coked up and will restrict the flow of exhaust and cooling. Eventually the engine will also overheat while pushing it at the higher RPM's. If these things do not do it for you, I would have the injectors checked. Sometimes they start to leak (not spraying properly) and cause similar problems.
John: Determine the engine ratings. Most of the modern diesels run at higher RPM's than the older ones. The other thing that they have in common is they are normally designed to run at 70-80% of the max rating. If you engine is rated at 3600 rpms then you would be looking at 2500-3000 rpms. We already know that you a pumping out gray/black smoke at these rpms, so you can start with the prop to be sure that it is not fouled or something wrapped around the shaft. The mixing elbow on the Yanmar's when cooled by salt water are notorious for clogging up. This is usually not a terrible thing to try to diagnosis yourself. You just need to remove the exhaust manifold and elbow. Then inspect where the cooling water and the exhaust come together. This gets Coked up and will restrict the flow of exhaust and cooling. Eventually the engine will also overheat while pushing it at the higher RPM's. If these things do not do it for you, I would have the injectors checked. Sometimes they start to leak (not spraying properly) and cause similar problems.
If you should search for marine engine
ratings, you will find something like this: Marine Engine Power Classification: Marine Engine Power Classification: A 1 - Short Range Fast Pleasure Service (High Performance Pleasure Crafts) - Boat Type and Use: Pleasure and military boats with a gliding hull and high speed or half-gliding and displacing pleasure hulls utilizing maximum power for short periods alternating with extended periods with a speed lower than maximum speed. Examples: Pleasure Hulls, High Speed Boats for military or state bodies - Engine Utilization characteristics: Maximum power utilization limited to 10% of time, cruising speed with engine rpm < 90% of calibration rated rpm. Use limit =300 hours/year. B - Light Duty - Boat Type and Duty: Light craft for recreational, commercial, or military duty with frequent speed variations. Examples: Pleasure Craft, Chartering, Passengers Transport, Fast Patrol Boats, Police, Coastal Guard, Rescue, Special Corps. - Engine Duty Cycle: Full throttle operation < 10% of use period, cruising speed at engine rpm < 90% of rated speed setting. Maximum usage = 1500 hours per year. C - Medium Duty - Boat Type and Duty: Work boats, military, light fishing boats, taxis, short distance seasonal passenger transport, fire-fighting boats. - Engine Duty Cycle: Full throttle operation < 25% of use period, cruising speed at engine rpm < 90% of rated speed setting. Maximum usage = 1500-3000 hours per year. D - Heavy Duty - Boat type and Duty Fishing boats, work and passenger transport with the possibility to utilize the engine continuously at maximum rating. Examples: Fishing boats, work and passenger transport, and towboats. - Engine Duty Cycle: Maximum rating utilization up to 100% of use period for unlimited hours per year. Most of the engines sold for sail boats are rated for pleasure duty. The very same engines can be classified for all four service duties by the manufacturer. They simply reduce the max horse power and rpm ratings. Often as much as 50 percent from pleasure service to workboat service.
ratings, you will find something like this: Marine Engine Power Classification: Marine Engine Power Classification: A 1 - Short Range Fast Pleasure Service (High Performance Pleasure Crafts) - Boat Type and Use: Pleasure and military boats with a gliding hull and high speed or half-gliding and displacing pleasure hulls utilizing maximum power for short periods alternating with extended periods with a speed lower than maximum speed. Examples: Pleasure Hulls, High Speed Boats for military or state bodies - Engine Utilization characteristics: Maximum power utilization limited to 10% of time, cruising speed with engine rpm < 90% of calibration rated rpm. Use limit =300 hours/year. B - Light Duty - Boat Type and Duty: Light craft for recreational, commercial, or military duty with frequent speed variations. Examples: Pleasure Craft, Chartering, Passengers Transport, Fast Patrol Boats, Police, Coastal Guard, Rescue, Special Corps. - Engine Duty Cycle: Full throttle operation < 10% of use period, cruising speed at engine rpm < 90% of rated speed setting. Maximum usage = 1500 hours per year. C - Medium Duty - Boat Type and Duty: Work boats, military, light fishing boats, taxis, short distance seasonal passenger transport, fire-fighting boats. - Engine Duty Cycle: Full throttle operation < 25% of use period, cruising speed at engine rpm < 90% of rated speed setting. Maximum usage = 1500-3000 hours per year. D - Heavy Duty - Boat type and Duty Fishing boats, work and passenger transport with the possibility to utilize the engine continuously at maximum rating. Examples: Fishing boats, work and passenger transport, and towboats. - Engine Duty Cycle: Maximum rating utilization up to 100% of use period for unlimited hours per year. Most of the engines sold for sail boats are rated for pleasure duty. The very same engines can be classified for all four service duties by the manufacturer. They simply reduce the max horse power and rpm ratings. Often as much as 50 percent from pleasure service to workboat service.
perky Perkins
I have a Perkins M50 in my OC400 that I run at 2000 RPM with a three-blade Max-Prop. This gives me 7 knots all day long, for days at a time, burning fuel at .8 gph. The engine is happy at that speed and runs with no smoke at all.
I have a Perkins M50 in my OC400 that I run at 2000 RPM with a three-blade Max-Prop. This gives me 7 knots all day long, for days at a time, burning fuel at .8 gph. The engine is happy at that speed and runs with no smoke at all.
Check manufacturers specifications...
for maximum rpm limit, then adjust for specific application. The displacement of your boat, the condition of the bottom and the size and pitch of your prop will dictate your maximum RPMs. If you have a clean bottom (the boat) and recommended prop and your air filter and fuel filters are in good operating condition you will attain maximum rpms and boat speed before it starts smoking. When the engine starts smoking is being fed more fuel than it can handle so back off and run at the highest rpms you can cleanly sustain. Some boats achieve hull speed under power and others don't.
for maximum rpm limit, then adjust for specific application. The displacement of your boat, the condition of the bottom and the size and pitch of your prop will dictate your maximum RPMs. If you have a clean bottom (the boat) and recommended prop and your air filter and fuel filters are in good operating condition you will attain maximum rpms and boat speed before it starts smoking. When the engine starts smoking is being fed more fuel than it can handle so back off and run at the highest rpms you can cleanly sustain. Some boats achieve hull speed under power and others don't.
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