First verdict on Series 60
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• As previously reported, Detroit Diesel has both sizes of its new DDEC-equipped Series 60 four-stroke engines on trial with British operators, and CM has tracked them down.
The 11.1-litre model is available in versions from 186KW (250hp) to 261KW (350hp); a 242KW (325hp) unit is running in a Railfreight Foden. The 12.7-litre Series 60 is rated from 261KW (350hp) to 317KW (425hp). Since 3 September last year, a 272KW (365hp) model has been power ing a sleeper-cabbed 4 x2 Foden tractive unit running with tipper operator Alfred Hymas's fleet out of Burton Leonard, near Ripon.
We spent a 12-hour shift hauling a tri-axle trailer over 400km (248 miles) to bring you the first evaluation of Detroit Diesel's new family of engines. Operating conditions ranged from the M62 to the tightest of hill routes and urban traffic.
The Series 60's Detroit Diesel Electronic Control is similar to Scania's EDC system. It offers a number of at-aprice advantages over mechanically governed engines. The usual ones like built-in cruise control, top speed governing, turbocharger protection on start up, and key stop are built upon, with a cleaner exhaust and options like automatic power reduction and engine shutdown to prevent damage from low oil or water and overheating.
The engine in Hymas's Foden was also fitted with a Jake Brake. Though noisier than a transmission retarder like Voith's hydraulic range or the electromagnetic type from Telma, it demonstrated how other system's electronics can be made to work alongside the engine's management system.
The Foden left the factory with a Caterpillar engine and Fuller 13-speed gearbox. Detroit changed the engine and added the extra switches and diagnostic warning lights on the dash.
Climbing aboard the first clues, to what lies beneath the cab are those three switches and three warning lights.
The simple extra controls worked well, mounted on a spare flat space on the dashboard to our left. Turn the key to 'run' and the three extra lights are lit with the regular ignition. These are check and stop warnings for the DDEC and the cruise control. They go out after three seconds once the system has checked itself over.
The throttle has only an electrical linkage to the engine, so no pedal control is necessary on start up. In fact drivers who like to rev the rivets of an engine after starting up are prevented from doing so.
Temperature sensors set the idle speed between 600 and 1,000rpm, depending on the engine's needs. Once warm, tickover speed is maintained by DDEC at 600rpm.
Economical
Front then on the big Detroit drives like a high-torque Cummins or Caterpillar. It can pull hard down to 1,000rpm and will hug through tight corners as low as 800rpm. However, in normal driving it is most economical between 1,200 and 1,80Orpm.
After a few kilometres the temperature creeps up and the Jake Brake can be switched in. It converts up to 80% of engine power to slow the truck whenever it is in gear and throttle and clutch are not touched by the driver. A light touch on the throttle trips out the brake when the engine is sufficient to check the truck's speed.
The cruise control works like a car's. The first switch turns the system on and a second is depressed to set and hold the road speed, for example, at 971(mili (60mph) on motorways. The driver can then lift his foot from the accelerator and the truck will maintain its speed independent of hills. A dab on any pedal will knock out the cruise control.
Immobilised
The Jake Brake is immobilised when the cruise control is in use to prevent the engine and retarder from working against each other. Should the road speed rise above 60mph, say on a downhill stretch, a dab on the clutch pedal brings the brake in. When the road speed drops back to 97km/h (60mph) the driver can either depress the throttle to maintain his speed manually or press the cruise control's resume switch to automatically return the truck to its pre-set speed.
It did not take long behind the wheel to begin to appreciate why the Series 60 has become such a hit in the US. Apart from its reliability (Hymas' engine has needed no attention so far) the engine's overall flexibility is good. Running fully freighted we found it easier to use the top two splits, in other words, drive the 13-speed box as though it were a 10speeder. Pulling away was practical in second gear on the flat with a block change to fourth followed by fifth. A one, three, five pattern worked equally well.
At tickover the engine develops 1,170Nm (8641bft) of torque. This is sufficient for pulling away at 38 tonnes and for reversing under a fully laden trailer without touching the throttle.
With just one service so far — the oil change interval is 32,000km (20,000 miles) — the truck is returning an average of 6.5mpg (43.461iti 100km). The Detroit handbook says that the engine needs no running-in period before full power can be applied, but that 120,000-150,000km (74,40093,000 miles) is required to fully loosen it up for the best economy. Hymas driver Mike Simpson says that economy has yet to improve, but that the engine will now pull one gear higher on certain hills.
Fleet engineers should like this engine as combinations of flashes from the dashboard warning lights reveal a code number which identifies faults.
A tamper-proof life history is also held in the computer, which buyers can interrogate with a dealer's help.
We are impressed with this engine. The Series 60 four is nothing like its Series 71 and 92 two-stroke predecessors. Its high torque at low revs style is not new, of course, and so it will share a common problem with other modern engines if launched in Europe. Modern engines need properly trained drivers if the promise of their economy is to be delivered.
0 Detroit Diesel has confirmed that its two Series 60 engine field trials will continue without direct backing from any manufacturer. Roger Rice, area sales manager for the UK and Scandinavia, says that the next step is to take figures gained from the field trials and show them to other potential customers. "We will look at a few key fleets. Now we can go armed with a little experience." Oby Danny Coughlan