Detroit Diesel Electronic Control

That gap has been narrowing as environmental and, to a greater extent, fuel consumption concerns come home to roost. And though the number of truly modern (multi-valve, OHC) high-speed diesel designs cruising around the waterways of the world is still relatively small, there have still been many worthwhile advances of late.

One of the most successful uses of on-highway technology has been the application of largely automotive-sourced electronic engine management systems.

Though the marketers have had much to say about this subject, in simple terms this is the marine application of the same sort of technology that has enabled cheap and reliable electronic fuel-injection to be fitted to a wide range of petrol engines. Indeed, without having to control the ignition function of the powerplants, it could be said the diesel systems are even simpler.

Both the petrol and diesel systems have been made possible by one key component the faster, more compact and more reliable microprocessors that seem to have pervaded every mechanical aspect of life.

The first of the major marine powerplant players to jump into the electronic engine control arena was Detroit Diesel who developed the Detroit Diesel Electronic Control (DDEC) system in conjunction with US company, Sturdy Controls. Automotive-sourced but adapted and further developed to include integrated controls, the system was released off-highway as long ago as 1985. It has since evolved and improved along with progress in computer technology.

Taking full advantage of current advances, Detroit will release its fourth generation system shortly. It's an improvement on the installation Trade-A-Boat sampled recently in its third generation guise (DDEC III) and will be available Down Under later this year on the company's 71, 92 and 149 Series powerplants as well as its soon-to-be-released 60 Series.

Unlike most other electronic controlled marine diesels, DDEC is a fly-by-wire system. That is, the system entirely replaces the proprietory mechanical and electro-mechanical controls found at both ends of 'normal' powerplant/control installation with a fully-integrated Detroit designed and supplied control-to-engine link.

As well as replacing the control componentry of the powertrain, DDEC takes care of engine governing and fuel-injection duties. The basis of the system are a relatively simple 'read-only' electronic control module and electronically-controlled fuel injectors which work together to precisely meter and time the fuel delivery to each cylinder. This system is configured so that it automatically compensates for intermittent accessory loads and accurately synchronises powerplants (within 10rpm) in multi-engine installations.

Of course, there's more to the system than this and engine protection is an important weapon in DDEC's arsenal.

Indeed, the DDEC 'brain' applies its programming to the whole gamut of engine functions, informing the captain of a range of faults and protecting the engine/gearbox assemblies in the case of inappropriate use.

An example? A skipper can perform a crash stop from WOT (Wide Open Throttle) forward to WOT reverse on a DDEC-equipped craft and the system's programming is 'smart' enough to ramp the throttles down, change gear when safe and ensure that the engines don't stall by accelerating them into reverse at the appropriate moment.

But unlike very early electronic control systems, in the case of a potentially damaging fault the choice to shutdown or 'limp home' is entirely in the hands of the operator.

Of course, the system is also 'smart' enough to allow individual control of engines in berthing or sportsfishing applications.

An interesting added feature for both of the above is the system's slow idle function, which drops one bank of cylinders in the DDEC-equipped V-engines.

A more commonly considered benefit of the system is the improved performance (increased torque and horsepower up around 3%) and acceleration DDEC-equipped powerplants offer. Most mechanically-controlled engines incorporate a throttle delay mechanism. However, as this is not required with electronically-controlled powerplants, 'out of the hole' acceleration is immediate with a high percentage of maximum torque available in a fraction of a second.

According to Detroit, DDEC offers a number of other advantages, including reduced smoke under acceleration and cold start conditions.

It also offers a wealth of powerplant information via the most visible component of the DDEC system the Electronic Display Module (EDM).

This instrument replaces the battery of gauges usually associated with high-performance diesels and deserves a story in itself.

In brief, however, the unit displays engine performance with control, programming, warning and historical data accessible via a system of menus.

The EDM offers a full range of engine and gearbox monitoring functions with the standard display reading engine rpm, oil pressure and temperature, instantaneous fuel burn, gearbox pressure, temperature and position, battery voltage and active station number. The system supports up to six control stations and control can be transferred from one to another with the push of a button.

The EDM also has a menu that allows the skipper to monitor such functions as engine load (handy when propping a new craft), trip fuel and trip hours. It also displays all additional information in a text window. In the case of a fault, detailed alarm messages scroll through in this window.

Much has been made of the teething problems associated with early DDEC powerplants. It's a situation Detroit Diesel Corporation (DDC) doesn't shy away from. In fact, spokesman Phil Robinson was happy to talk candidly to Trade-A-Boat on the subject.

According to Robinson, the majority of early problems stemmed from incorrect installations. He adds that these problems have largely been overcome, thanks to close contact and a heavy emphasis on educating big and small boat builders on the importance of correct installation.

Robinson also makes the point that the cost premium of DDEC-equipped powerplants has often been overstated in the past. In fact, he claims that comparisons conducted by DDC show that there is often a cost saving, given that most DDEC installations include all the required controls and associated parts and pieces.

Trade-A-Boat's most recent experience with DDEC came at the helm of the Port Stephens (NSW)-based Steber 43 Moet, the personal craft of Soldiers Point Marina proprietors Ken and Moyra Stewart.

Though it only had single-figure engine hours, Moet's 6V-92s proved both willing and muscular.

And with impressive acceleration out of the hole, it hinted that there was more to come than the recorded 30kt once the powerplants loosen up.

As you'd expect, all the DDEC functionality performed like a charm.

Accurately synchronised, the V-sixes were truly humming at Moet's 2100rpm 26.5kt cruise.

In fact, to the writer's ear that Detroit diesel music alone made DDEC's long development worthwhile.