C9 Caterpillar

Caterpillar's C9 is an extension of a family that now includes the C12, C18, C30 and C32, with the C7 due for release at the 2004 Sanctuary Cove Boat Show.

As with the C12 and C18, the C9 is a straight six with electronic engine management that enables it to comply with IMO requirements for diesel-engine exhaust emissions, such as NOX and black smoke.

This engine was designed for planing hulls around 12m in twin installations (its torque would make a Black Watch 40 really perform) and has a piston displacement of 8.8lt from a 112mm bore and 149mm stroke. It develops 503hp at 2500rpm and is rated for 250?1000 hours of operation per year and up to half an hour at wide open throttle (WOT) in every six hours or one hour WOT in every 12.5 hours. Engine output is guaranteed up to 50°.

In bobtail form the C9's weight of 947kg is 37kg more than the nearest diesel for piston displacement, the 7.8lt Iveco Cursor 500, which develops 493hp at 2600rpm. The C9 weighs 87kg more than Volvo Penta's 7.28lt 74P EDC (now called the TAMD75P EDC) which develops 480hp at 2600rpm and 122kg over Yanmar's 7.4lt 6CXM-GTE2, which has a maximum crankshaft output of 493hp at 2900rpm.

Unlike the European and Japanese engine manufacturers Caterpillar rates its engines on the traditional horsepower-to-kilowatt system where 1.0hp = 746W, not 736 - which is also the Japanese PS system of power measurement. Caterpillar provides a kilowatt output, brake horsepower output and metric (PS) horsepower output on its engine specs, so buyers know exactly what power they are getting.

NO PEERS FOR TORQUE
Lindsay Arndt of Energy Power Systems Australia, the Australian distributor of Cat Marine diesels, agreed with me that torque output is more important than maximum kilowatt or horsepower output when it comes to directly comparing diesels.

In a planing hull, a rapid torque rise from fast idle and plenty of torque at low rpm are what's needed to make boating more pleasurable and safe, particularly when crossing bars.

One European engine manufacturer doesn't even supply torque figures for its diesels, instead preferring to concentrate on engine features. So there's no way buyers can compare apples with apples!

Although the C9 weighs substantially more than its closest competition, the additional torque it produces closes the gap. For example, the Cursor 500 produces a peak of 1520Nm between 1800 and 2000rpm, the Volvo Penta engine 1432Nm at 1600rpm, while the Yanmar produces 1500Nm at 2000 to 2200rpm.

But the C9 produces 1867Nm at 1600 to 1800rpm and although it's four per cent heavier than the Cursor 500 is produces 23 per cent more torque. Compared to the Volvo Penta it's 10 per cent heavier but produces 30 per cent more torque. The Yanmar is closer for torque-to-weight and the C9 weighs 15 per cent more for a 24 per cent increase in torque, but then maximum torque is produced at 500 fewer revs - important for getting a gameboat out of the hole.

At 1400rpm the Yanmar's torque output is 1100Nm compared to 1720Nm for the C9 at the same revs, while at 2200rpm the C9 still produces 1600Nm. At WOT the C9 produces 1400Nm, whereas the Yanmar falls off to 1200Nm. The Cursor 500 produces 1200Nm at 1400rpm and 1350 at WOT.

Unlike the C9, Cursor 500 and Volvo Penta engine, the Yanmar misses out on electronic engine management and has to make do with fixed fuel injection timing, which is either too advanced below the maximum torque range or too retarded above this, limiting operating efficiency.

An example of this is the Yanmar's fuel consumption - 100lt/h at 2900rpm compared to 99.1 for the C9 and 97.5lt/h for the Cursor 500. Unfortunately Iveco doesn't supply prop power curves to enable the working out of real-time midrange fuel consumption, but at maximum torque the Yanmar is using 36lt/h whereas the C9 uses 33.5 despite being able to produce significantly more torque.

The C9 uses electronically controlled hydraulic unit injectors whereas the Cursor 500 and Volvo Penta engine have the preferred European system of high-pressure common rail. The C9's Electronic Control Module (ECM) automatically alters fuel injection timing according to engine load, so that in headseas injection timing is retarded to reduce engine load - and once running downwind where engine load is reduced, the timing is advanced to increase engine efficiency and reduce fuel consumption.

The company says it randomly subjects ECM diesels to extreme heat, cold, vibration, dust and electromagnetic interference under controlled conditions to simulate real-life situations.

ECMs have a memory function that records engine hours, fuel consumption and load factor, such as hours spent idling in a specific time. They also store problems such as faulty fuel injectors and the resulting incomplete combustion in one of the cylinders, and sensors located strategically around the engine measure inlet air and fuel supply restriction, low oil pressure, abnormal crankcase pressure and exhaust temperature as well as overheating of the engine coolant and transmission oil.

A multi-engine synchronisation facility enables a single throttle to be used if required, and engine revs are electronically limited to prevent a damaging overspeed situation.

COMPACT DIMENSIONS FOR OUTPUT
With its significantly greater piston displacement than the closest competition the C9 should be bulkier, but in bobtail form it's 1409mm long, 974mm wide and 983mm high. The Cursor 500 is 1807 x 956 x 943mm, the Yanmar 1504 x 877 x 905mm and the Volvo Penta 1142mm long from flywheel to alternator drive belt, 794mm wide and 937mm high.

As with the entire C-series range, the C9 is available for handed mounting, and maintenance components such as the fuel priming and transfer pumps and the oil filter and oil dipstick may be mounted to port or starboard. The engine-oil cooler is located at the forward end of the engine.

A transmission-fluid cooler is also standard and the raw (sea) water cooling pump is gear driven. The engine-oil change interval is 250 hours using Caterpillar SAE 10W30 or 15W40 oil depending on the anticipated ambient temperature range.

For more information, contact Lindsay Arndt, tel (07) 3276 8441 or 0417 357 402, or email lindsay.arndt@energypower.com.au.