Isuzu meets emmisions requirements with Direct-Injected L-Series Current and prospective users of Isuzu L-Series engines will be pleased to learn that the new EPA Tier 2 compliant, direct-injection (DI) versions have the same physical footprint as pre-tier 2 models. Maintaining the same footprint simplifies what would be an otherwise ardous re-engineering effort to modify equipment to house the new engines.

With over 1000 engineers devoted to diesel engine development worldwide, Isuzu has achieved wide recognition for its industrial engine operations with OEM accounts around the world. Here in the U.S., American Isuzu PowerTrain strives to expand its market share and level of service by leveraging on Isuzu’s vast diesel engine resources, infrastructure and brand equity.

The industrial engines are developed from the technology of well-proven automotive engines. It is certainly the automotive sector that represents the leading edge in gaseous emissions, but that is also true of customer expectations with respect to noise, vibration and ease of use. Isuzu produces more than 800,000 diesel engines per year and plans to produce 1.8 million by 2005.

The L-Series diesels will still be in the picture at that time and that was always the plan from the time they were introduced by American Isuzu to the U.S. market back in 1993, replacing the well-known K-Series. The three-cylinder L-Series engines were joined by four-cylinder versions in 1995. These engines were conceived to be among the quietest, most compact, lightweight, liquid-cooled engines in their class and the plan was that this basic platform would meet CARB, EPA and other applicable emission standards well into the future.

If one looks at the global automotive picture, it is estimated that fully 90 percent of the vehicular diesel engines will be direct injected after 2000 and the percentage would be even higher were it not for Third World production. The main motivations are the reduction of CO2 and particulate matter emissions and the improvement of fuel economy.

So this is the battleground and direct injection appears to be the weapon of choice. And from this massive automotive capital base flows the technology base that will then be applied to other engine applications. Virtually all automotive diesel engines above 3.5 L displacement already use DI technology and many smaller automotive engines are also DI.

Many of Isuzu’s engines were developed for automotive as well as industrial use. Included would be the J-Series and the B-Series in the under 100 hp range. The L-Series, however, was developed strictly for industrial use, yet it too makes use of the tools of automotive engine design.

With the new DI three-cylinder model 3LD2 displacing 1499 cc and the four-cylinder 4LE2 displacing 2179 cc, the L-Series is the smallest series that Isuzu manufactures today. The 3LD2 has a bore and stroke of 83.1 x 92 mm and a maximum output of 34.8 hp at 3000 rpm, with peak torque of 73.5 lb.ft. at 1800 rpm. The 4LE2 has a bore and stroke of 85 x 96 mm and a maximum output of 54.4 hp at 3000 rpm, with peak torque of 113.4 lb.ft. at 1800 rpm. All ratings are SAE J1995 gross hp. Dry weight of the 3LD2 and 4LE2 is given at 290 and 396 lb. respectively.

Despite the very small differences in bore and stroke, the engines are virtually identical in other respects. Isuzu insists new DI L-Series still offers OEMs a single engine family with high component commonality in both three- and four-cylinder configurations.

The compact and lightweight L-Series feature one-piece, cast iron blocks and heads, and overhead valve design with two valves per cylinder. The block is deep skirted for strength, rigidity and durability. Unit injection pump housings are cast into the blocks. The engine water jacket is formed with a one-piece casting core to eliminate irregular cooling passages.

The ductile iron crankshaft is underslung to the block with five main bearings for the 4LE2 and four main bearings for the 3LD2. The flame-hardened, chilled casting camshaft is mid-mounted in the block and it is gear driven. The camshaft is of one-piece design.

Low noise and vibration were very active design themes for the L-Series. A single camshaft actuates unit pump injectors as well as intake and exhaust valves. Valves are actuated through forged steel push rods and aluminum die cast rocker arms. Gears are helical and the number of gears in the gear train is only three and this permits a smaller gear cover with a lower profile and reduced forward noise emissions.