MTU's Series 2000 diesels

The various models within MTU's Series 2000 range of marine diesels are finding their way into some of the best enginerooms Down Under.

Based on the same direct-injected four-stroke 90° vee design, the eight, 12 and 16-cylinder models all boast multi-turbo configurations with intercooling, four-valve heads and electronic engine management. The same 130mm cylinder bore and 150mm stroke is used throughout the range with a displacement of 1.99lt per cylinder and a low compression ratio of 15.2:1.

Replaceable cast-iron wet cylinder-liners are used and the pistons have a chrome/ceramic coating. Unusually, the valves are located at the 'corners' of the combustion chamber with a central injector, supplied by individual injection pumps mounted on the cylinder block.

Individual cast-iron cylinder-heads are considered to improve component access and reduce downtime.

The Series 2000 crankcase is a single-piece unit of cast-iron and has integrated water and oil channels. The crankshaft is forged steel with bolted-on counterweights. The exhaust lines are watercooled essential when the exhaust gas temperature, after leaving the turbocharger, is 500°C!

The Series 2000 range is equally at home in tropical or cold climates. For example, according to MTU's own figures, even with a 45°C intake air temperature and 32°C seawater temperature the 8V 2000 M90, 12V 2000 M90 and 16V 2000 M90 models each lose only 1.5% of their rated crankshaft output. The latest higher-performance version of the 12V 2000, the M91 model, loses 3%.

Equally impressive, though not of real concern in the Australian marine market, is that at -10°C the engines don't require glowplug or coolant preheating to start.

A nice touch is the 2000 Series optional, electrically-clutchable bilge pump operating from a PTO. This has a capacity of 167lt/min (10 cubic metres per hour) at engine revs of 1500 and comes standard with flameproof hosing.

The electronic engine management system (ECU-MDEC) fitted to all models senses changes in barometric pressure, engine load, revs, oil pressure, coolant and oil temperature and exhaust temperature. Should any abnormalities be experienced, the control panel light flashes and an alarm sounds. A diagnostic test facility is standard.

The ECU-MDEC operates in conjunction with the gearbox to provide a 'trolling' function, where some gearbox 'slip' is allowed to reduce propshaft revs at low speeds.

Like most electronic management systems this one eliminates the need to run control cables from the engineroom to helm station, reducing transmitted vibration, maintenance down the track and installation time.

All Series 2000 models have a 24V electrical system and all models comply with IMO 2000 emission regulations.

Unfortunately, despite a number of requests, MTU Australia was unable to supply any torque figures for the Series 2000 range models. This is the first time a diesel engine distributor was unable to do so, in my opinion a real shame as an engine's torque output is more representative of its performance than maximum rated power particularly if the torque band starts well down in the rev range.

The MTU Series 2000 engines are available with three different ZF gearbox configurations. One is the parallel offset series, where drive from the crankshaft output flange drops to the same plane as the propshaft input flange.

Next is the Offset 'A' Down Angle, where the crankshaft remains virtually parallel to the static waterline but the propshaft angles down several degrees. (This would be my choice as the engine can be installed at less of an angle, which lowers the forward end for reduced height encroachment on accommodation).

Third is the V-Drive, where a jackshaft runs up 3° from the engine to the box forward. A 10° down-angle then passes the propshaft back under the engine.

Unlike most hydraulic gearboxes, where 5-10% of the engine's power is lost through the box, the ZF range loses only 3%.

With the availability of ZF's two-speed gearboxes (TAB December 1999), perhaps MTU may in the future look at offering these instead of the single-speed units. At least in the case of the 8V 2000 M90 and 12V 2000 M90 at the time of compiling this review there was no ZF two-speed box capable of handling the power of the 12V 2000 M91 and 16V 2000 M90.

THE RANGE
Displacing 15.92lt, the 8V 2000 M90 develops a maximum pleasure duty (planing hull) output of 900 hp (672kW) at 2300rpm. It has a maximum fuel consumption of 195lt/hr but in the maximum efficiency zone between 1500-1800rpm, where the engine is developing from 523-664 hp, the consumption is 108-137lt/hr.

Oil consumption is rated at 0.5% of fuel consumption and the sump holds 70lt. The recommended time between major overhauls is 6000 operating hours.

Fitted with a ZF IRM 350 A-1 gearbox the 8V 2000 M90 is 2095mm long, 1216mm wide and only 1075mm high. The dry weight is 2320kg.

The IRM 350 box has a 7° down-angle and is available with a choice of ratios from 1.286:1 to 2.636:1. A suitable ZF two-speed box is the IRM 350 ATS, which has ratios from 1.286/1.032:1 to 2.947/2.367:1.

The 12V 2000 M90/M91 is a 23.88lt, V-12 diesel which develops 1350 hp (1007kW) at 2300rpm in the M90 version and 1480 hp (1103kW) at 2350rpm in the new high-performance M91 version.

Maximum fuel consumption of the M90 is 288lt/hr and in the maximum efficiency zone from 1680-1850rpm and 912-1032 hp, the fuel consumption is 177-200lt/hr. The M91 has a maximum consumption of 326lt/hr but uses 177-200lt/hr in the maximum efficiency zone between 1680-1850 revs, where again the engine develops 912-1032 hp.

Both engines have a 105lt oil sump and oil consumption is 0.5% of fuel consumption. Recommended time between overhauls is 6000 hours for the M90 and 4000 for the M91.

Oddly enough with a ZF BW 190 A box the M90 is 40mm longer than the M91 with ZF BW 195 A box, which measures 2560mm long. Both engines are 1400mm wide but the M90 is only 1222mm high compared to 1465mm for the M91, which has exhaust stacks. The engines each have a dry weight of 3195kg.

Both ZF boxes have a 10° down-angle and ratios from 1.538:1 to 2.920:1. A suitable ZF two-speed box for the 12V 2000 M90 is the BW 190 ATS, which has ratios from 1.273/0.962:1 to 2.920/2.207:1.

Largest of the Series 2000 models, the 16V 2000 M90 is a 31.84lt, V-16 which develops 1800hp (1342kW) at 2300rpm.

The maximum fuel consumption is 385lt/hr but in the massive maximum efficiency zone from 800-1450rpm and 268-925 hp, the fuel consumption is between 53-184lt/hr. The oil sump holds 134lt and again oil consumption is 0.5% of fuel consumption. The overhaul interval is 6000 hours.

Fitted with a ZF BW 255 AP box the 16V 2000 M90 is 3075mm long, 1400mm wide and 1270mm high, not including the exhaust stacks. The dry weight is 3765kg and the ZF BW 255 AP box has a 10° down-angle and ratios from 1.574:1 to 2.536:1.

IN SUMMARY
Though somewhat heavier than its most logical competition (MAN), MTU's Series 2000 models appear to be engineered for a low downtime lifespan. Indeed, a popular choice among prestige boatbuilders both here and abroad, MTU engines have an enviable reputation for performance and longevity.

From a personal viewpoint, it's a shame that with the smaller models the company didn't opt for two-speed gearboxes out of the box.

For more on the Series 2000 diesels, contact Bernard Stojkovich at MTU Australia, tel (02) 8822 7000.