GM 2300 engine
The 2300 was a 2.3 L/140 cu in (2287 cc) straight-4 automobile engine produced by General Motors from 1971 through 1977. The Vega engine, as it became known, was unusual for the time with an aluminum block and cast iron SOHC head. An advanced feature of the engine was the fact that it did not have traditional cast iron cylinder liners as a cost-saving measure. Instead it used silicon impregnated into the aluminum cylinder bore using the Nikasil coating process, a design that has now become very common. At the time this approach was not generally successful, and excessive cylinder wear allowed hot combustion gases to bypass the piston seals, leading to hot operation and oil consumption, which when coupled with the initial inadequate coolant flow and problems with the cooling jackets sometimes resulted in warping of the aluminum engine block and premature engine failure.
The block itself was designed in partnership with Lotus, who planned to use it as the basis for a inexpensive racing engine. However, Lotus never used the Vega block or anything similar. The high tech aluminum block had cast iron main caps, a cast iron crank, and an enormous cast iron cylinder head that weighed almost as much as the whole short block. The tall, top heavy, long-stroke Vega motor had major vibration problems, "cured" with huge rubber motor mounts. With the hood open and the engine idling, "it would be rocking and bouncing around like it was trying to escape." 
Early models overheated due to poor cooling passage design. Overheating was a serious concern for Vega engines, since the lightweight engine block was of an open-deck design, and severe overheating would cause the cylinder barrels to warp and pull away from the head gasket, causing coolant leaks into the cylinders. The 2300 engine typically burned oil due to both heavy cylinder wear , and poorly designed valve stem seals, and was both rough and noisy in operation. Road & Track reported at the time that this highly-anticipated engine was "a letdown" and "extremely rough and noisy". These engines only lasted a few years, with a horrible service record, while Chevrolet claimed the service problems (scored cylinders, scored walls) were mostly due to improper maintenance.
It was available with a 1 or 2 barrel carburetor and was used in the Chevrolet Vega and similar Pontiac Astre, and the later Chevrolet Monza and its H-body siblings: the Oldsmobile Starfire, Buick Skyhawk, and Pontiac Sunbird. The 2-barrel version, known as the L11 option, also included a hotter camshaft for a power increase of 20 hp (15 kW). The engine used a 3.501 in (89 mm) bore and 3.625 in (92.2 mm) stroke and 8:1 compression.
The 1976-77 2300 engine received a new cylinder head design incorporating hydraulic lifters to replace the unusual taper-screw valve adjusters, factory iron cylinder liners, improved coolant pathways, and better valve stem seals along with a new five-year, 60,000-mile (97,000 km) engine warranty. The engine's name was changed to Dura-Bilt in 1976 to declare that its problems had been resolved.
|Year||1 barrel||2 barrel|
|hp (kW)||ft·lbf (Nm)||hp (kW)||ft·lbf (Nm)|
|1971||90 (67) gross||136 (184)||110 (82) gross||138 (187)|
|1972||80 (60) gross||121 (164)||90 (67) gross||121 (164)|
|1973||75 (56)||115 (156)||85 (63)||122 (165)|
|1974||75 (56)||115 (156)||85 (63)||122 (165)|
|1975||78 (58)||120 (163)||87 (65)||122 (165)|
|1976||70 (52)||107 (145)||84 (63)||113 (153)|
|1977||84 (63)||117 (159)|
A Cosworth version of this engine was produced in 1975 and 1976. It was a version of the 2300 de-stroked to 3.16 in (80 mm) with special DOHC 16-valve heads and solid lifters. It produced 120 hp (89 kW) and 107 ft·lbf (145 N·m).