In a Discovery Channel Extreme Machines, a BMW 93,000 HP 16 cylinder turbocharged diesel was shown going into a new container ship. I believe they mentioned that the pistons were 17 feet tall, or possibly that was the stroke. Is there a theoretical maximum limit, other than materials or adding cylinders, that a diesel can attain? How do they turbocharge something that big? Hopefully it won’t break a rod and hole the hull[:)]
I remember seeing a link to a site a while back (about 2 years ago or so) that showed a super-size marine diesel similar to what you described. I believe that it had a bore and stroke in the range of 3-6 feet and turned over at a top speed of 100-110 RPM. The reason that such a large engine is being built is that shipbuilders want larger engines to minimize the need to gear multiple smaller diesels onto one propeller shaft.
Thinking about it, I don’t suppose there really is an absolute upper limit on the size a marine or stationary diesel could be made, assuming that the engineering on the thing were done correctly. As Paul notes, the rpm of the big marine diesels is very low – often direct connected to the propellor. Most of the bigger flavours are really assemblages of single cylinder diesels, all running on the same crankshaft and with a more or less common control system. Most of them can be run with one or more cylinders completely disconnected, if something goes amiss. Most of them also, these days, turn controllable pitch propellors, so there is no transmission.
UP829:
Regarding the possibility of repairing a broken rod, these engines are repair-in -place. They are so huge that they have access plates large enough for a person to climb through and actually go inside the engine (when the ship is in port and the engine is shut down).
Engineering students study P-V-T plots of Thermodynamic cycles of Internal combustion engines (Otto and Diesel cycles) that assume no losses due to acceleration and friction. These losses are why there is such a difference between the actual and theoretical efficiency of an engine. These low speed marine diesels are operating at about as close to this theoretical thermal efficiency as possible.
The Engine in first post is a MAN B&W not BMW, it stands for Burmeister & Wain.
http://www.manbw.com/engines/TwoStrokeLowSpeedPropEngines.asp?model=K98MC%20Mk7
A even larger diesel is available tru Wartzilla /Sulzer. its the 108 000 hp 12 cylinder monster version used in todays container ships. see:
http://www.bath.ac.uk/~ccsshb/12cyl/
Don’t tell Adrianspeeder - he’ll want to mount the beast in a pickup truck. THAT would be a monster!
Wow, That Sultzer crankshaft is bigger then my apartment building.[:O]
well a engin this sise shouldend be suprising railroads used giant reciprocating engins of this magnitude for a hundred yeas and there still seen occasionaly today they are called steam engins [;)]