Peugeot's new V-6 engine targets OEM applications

Diesel Progress North American Edition, Feb, 1997

The ES9J4 is a 24-valve, 3.0 L engine rated 194 hp at 5500 rpm, with 196 lb.ft. of torque at 4000 rpm. According to Peugeot, 88 percent of the engine's maximum torque is available at engine speeds as low as 2000 rpm. The engine features a 60 [degrees] angle between cylinder banks, dual overhead camshafts and four valves per cylinder for efficient combustion, lower emissions and improved power density, according to the company. The combustion chamber design and electronic control of the fuel injection and ignition are engineered to produce favorable specific consumption and response under all conditions, Peugeot said.

A primary design criteria for the ES9J4 engine was minimization of friction inside the engine and optimization of the fuel intake system which contributed to achieving low fuel consumption. The engine utilizes weight-saving aluminum in many areas, yet is intended to provide durability and flexibility in many possible applications. The aluminum alloy cylinder block is a closed-deck design, with cast iron cylinder sleeves. The crankcase has integral cast iron inserts, added during the casting process, to reduce vibration and noise. The engine uses an all-steel, four-main-bearing crankshaft which is balanced with five counterweights.

Each aluminum alloy cylinder head houses the combustion chambers, spark plugs, valvetrain, intake passages, and water circulation galleries. The camshaft housings and the valve covers are also made of aluminum alloy.

A 32 mm wide cogged belt drives the camshafts and the water pump. In addition to the timing. gear to drive the camshafts and the water pump, a vibration-damped accessory drive pulley is available to run off the crankshaft.

The connecting rods are shot-peened, forged steel construction with an oil hole at the small end to direct lubrication into the cylinder liners. The oil spray also cools the aluminum alloy pistons. The low-inertia, short-skirt design of the pistons includes a flat crown featuring four shallow valve clearance recesses, a design resulting from extensive development work on a Cray supercomputer, Peugeot said.

The camshafts act directly on the self-adjusting hydraulic tappets that actuate the valves. The inner surface of each tappet is designed to eliminate play, which could potentially cause valve chatter in a cold engine. The timing belt cover, made of synthetic material, is specially designed to further reduce operating noise. Its five partially overlapping sections are sealed together by silicone foam.

The variable volume air intake system, which consists of a two-part aluminum alloy intake manifold, is designed to increase response at all engine speeds. Both compartments are joined by two permanent links, one of which is long and the other short. The dimensions of these links are optimized to produce a change in intake behavior as engine speed changes. At low speeds, both chambers behave as separate air compartments, as if each one is supplying an individual three-cylinder engine. At high engine-speeds, however, they work together as if they were a single compartment, with an effective volume that is slightly smaller than the total of both, Peugeot said.

The engine has a high compression ratio of 10.5:1. A built-in anti-knocking device automatically adjusts timing advance. The new-generation Bosch MP 7.0 Motronic electronic control unit uses data - including engine speed and air pressure readings - to optimize fuel injection and ignition timing. The Bosch unit governs semi-sequential, multipoint injection and twin static ignition coils. Injection and ignition occur in two cylinders at a time. A Sagem BBC3.2 compact coil unit which contains three coils assures ignition; each coil fires the spark plugs for two cylinders at once.

The engine has two identical cast iron exhaust manifolds, one fore and one aft. The front manifold is pre-heated by hot air to stimulate fast catalytic action. The engine achieves very low emissions and meets the stringent EURO 96 automotive emission standard, according to the company.