Original spin

Posted on October 26, 2016 by Lucie Maluck, Images by mtu, Fotolia

Is it possible to compare a Series 8000 mtu engine with a Series 4000 genset engine?
Friedrichshafen, Germany

An mtu Series 4000 genset engine takes only 15 seconds to get up to full power from a standing start. By contrast a 13,600-hp Series 8000 marine engine needs nearly 90 seconds. So can you compare them?

The mtu Series 4000 genset engine can generate electric power after only nine seconds.

The simple answer is no. After all, 100-metre sprinters do not compete against marathon runners in the Olympics. The Series 4000 genset engine has to be up to speed very quickly when called upon so as to be able to generate electricity in the event of a power outage. In the case of a marine engine, on the other hand, it is not just a matter of speed. Like a long-distance athlete, it has to consistently produce a lot of power over a long period. Being the first out of the blocks in that type of race is not the decisive factor. So how do these two different athletic performers get themselves moving?

Warming up and loosening up

Just like real athletes, they have to warm up first – both engines are always preheated to 40°. The Series 8000 also has to loosen up its joints first and build up oil pressure at the crankshaft bearings. The Series 4000 does not need to because it is smaller and lighter and can supply itself with enough oil right from the start. And that gives the Series 4000 its first head start.

Electric or compressed-air starter

Next the engines are started up. On the Series 8000 marine engine, the starter is powered by compressed air, whereas on the Series 4000 it is usually electric. The starter turns the crankshaft by means of a pinion and ring gear until enough air is drawn into the cylinders and compressed so that fuel combustion can take place. A speed sensor detects the position of the crankshaft. That enables the electronic control unit to calculate precisely into which cylinder fuel should be injected first. Then combustion is initiated and the engine starts up. At this point, the starter pinion is still engaged – on the Series 4000 it remains so until the engine is rotating at 300 rpm, while on the Series 8000 the starter cuts out at only 140 rpm. The starter pinion then disengages.

It takes 90 seconds for a Series 8000 mtu engine to be ready to deliver its maximum power output of 13,600 hp.

The Series 8000 marathon-runner then accelerates up to its idling speed of 380 rpm, which it reaches after six seconds. If the captain then calls for full speed, he has to wait 82 seconds for the engine to reach its rated 1,150 rpm. But at that point it delivers a massive amount of thrust – its 13,600 hp make it one of most powerful fast-running diesels in the world.

World record of 15 seconds

The Series 4000 sprinter, on the other hand, accelerates up to its rated speed of 1,500 or 1,800 rpm right away. After nine seconds it is ready to deliver power to the grid via its generator. Six seconds later, it is up to maximum output. And that makes it a world-record holder – no other engine gets there as quickly.

Point of contact

Robert Welz
+49 7541 90 4675

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