Caterpillar C18 (December 2004)

Caterpillar has taken a different approach to the European competition with its C18, reports Andrew Norton

In the 1000hp power range MAN opts for a V10 while MTU opts for a V8 or V12. But Caterpillar has taken the unusual step of opting for a straight six, which of course has advantages and disadvantages compared to V-block engines.

The main advantage of a straight six is its relative narrowness, which improves maintenance and servicing access between the engines in twin installations and allows for easier access to the cylinders for overhauls. The main disadvantages are the greater engine height, which can create installation problems in boats with low saloon floors, and the longer block - a pain when the engine is installed hard up against accommodation spaces.

The best engine to compare to the 1000hp C18 is MAN's 18.3lt V10, which develops 1035hp at 2300 revs and was reviewed in detail a few years ago in Trade-A-Boat.

In bobtail form (minus gearbox) the V10 is 1637mm long, 1230mm wide and 1194mm tall. In comparison, the 18.1lt C18 is 1845mm long, 1058mm wide and 1159mm tall, so despite its upright cylinder layout (the MAN has a 90º vee) it's actually slightly lower. And of course in twin installations, the narrower block of the C18 increases space between the engines by 172mm or more than six inches!

The weight of both engines is very close: 1636kg for the MAN and 1586kg for the C18.

TOP TORQUE FOR OUTPUT
The real measure of success for the straight-six concept in this power range is the torque it develops compared to the V-block competition.

MAN says its V10 develops 3500Nm of torque from 1800 to 1900 revs and still develops 91 per cent of maximum torque at its rated revs of 2300. In comparison, the C18 produces an incredible 4115Nm at 1600 revs with 3025Nm at 1200 revs and the same at 2300 revs, both 73.5 per cent of maximum output.

The C18 has a flat power curve from 1800 to 2300 revs, and in "E" pleasureboat output rating can be operated at Wide Open Throttle for one hour in every 12.5 hours, or half and hour out of every six. The E rating is for 250 to 1000 hours of operation per year.

Part of the reason the C18 produces so much torque for its output is the long stroke design. Whereas the MAN has cylinder bore and piston stroke measurements of 128 and 142mm (the stroke is 11 per cent more than the bore) the C18 has a bore of 145mm and stroke of 183 - the latter 26 per cent greater than the bore. With its massive torque at relatively low revs, the C18 would be ideal for twin installations in hulls such as the Riviera 51.

The C18 also scores with lower fuel consumption: 195.7lt/h at WOT compared to 212 for the V10 MAN. Based on a standard prop power curve, at 1600 revs the consumption is only 59.2lt/h, where 1500Nm of torque is absorbed by the prop. The maximum fuel efficiency zone of the C18 is from 1400 to 1600 revs, where the specific consumption is only 201–205 grams per kilowatt hour - excellent for a turbo aftercooled engine.

FULL ELECTRONIC ENGINE MANAGEMENT
As with the C12 and C30 reviewed in Trade-A-Boat, the C18 has full electronic engine management, which automatically varies the fuel injection timing according to engine load and maintains the correct air/fuel ratio regardless of barometric pressure - so the C18 will operate as efficiently on hot, humid days as cool, dry ones, where the air is denser and consequently combustion efficiency is better.

Regular Trade-A-Boat readers will know that I'm a big fan of electronic management systems in marine engines. Providing they're fully waterproofed, cooled effectively and isolated from engine vibration, there's no logical reason why a system should ever fail. For example, Cat Marine's Electronic Control Modules are sealed to operate at a depth of 21m!

Random factory testing also subjects ECM diesels for extreme heat, cold, vibration, dust and electromagnetic interference under controlled conditions to simulate real-life situations.

And this reliability is what Cat Marine emphasises to potential buyers of its electronically controlled models, because ECMs also have a memory function that records problems such as faulty fuel injectors and the resulting incomplete combustion in one of the cylinders. The ECM records engine hours, fuel consumption and load factor, such as hours spent idling in a specific period of time.

ECM sensors measure inlet air and fuel supply restriction, low oil pressure, abnormal crankcase pressure and exhaust temperature, and overheating of the engine coolant and transmission oil. Sensors placed at strategic points around the motor update information 20 times per second, and via Satcom this information can be relayed to a shore station, eliminating the tedious need to download operating information from the ECM's memory to a laptop computer.

So, should a problem arise at sea, service personnel can meet the boat when it docks, saving a lot of downtime when the big fish are running!

The C18's ECM enables multi-engine installations to be easily synchronised and even a single throttle used if required, while ensuring each engine maintains steady revs according to the throttle setting.

Standard C18 equipment includes a corrosion-resistant aftercooler core and closed-circuit air cleaner/fumes disposal system, similar to positive crankcase ventilation in a car engine. Both the raw (sea) and heat exchanger waterpumps are gear driven, and the expansion tank is integral with the titanium-plate heat exchanger.

The fuel priming and fuel transfer pumps and fuel filter is handed for twin-motor installations, to starboard on the port motor and port on the starboard unit, as are the engine oil cooler, canister-type oil filter and dipstick. A PTO facility is also standard for powering hydraulic pumps.

There are three separate rocker covers for the six cylinders to allow for better access without the complication of individual covers, while the alternator is mounted above the crankcase centreline and away from any bilge water. The oil change interval is every 250 hours, using 10W30 or 15W40 oil.

The standard 24V instrument panel includes maintenance-due and diagnostic lamps. Accessory equipment includes air starting, 12 or 24V alternators, a cooling water jacket heater for very cold climates, an OEM wiring harness and a spare parts kit.

For more information on the C18, contact Lindsay Arndt at Energy Power Systems, tel (07) 3276 8441 or 0417 357 402, or email lindsay.arndt@energypower.com.au.

Published : Wednesday, 1 December 2004
Issue : December 2004

---

disclaimer

Prices and specifications supplied are for the market in Australia only and were correct at time of first publication. BoatPoint Australia makes no warranty as to the accuracy of specifications or prices. Please check with manufacturer or local dealer for current pricing and specifications.