Friday, August 12, 2011

Chevrolet vega 1974 by rotor engine

Chevrolet Vega
1972 Chevrolet Vega GT Hatchback Coupe
Manufacturer Chevrolet Division
of General Motors
Also called Vega 2300
Production 1970–1977
Model years 1971–1977
Assembly Lordstown Assembly,
Lordstown, Ohio, United States
Sainte-Thérèse Assembly-
Quebec, Canada
Successor Chevrolet Monza
Class Subcompact
Body style 2-door notchback sedan
2-door hatchback coupe
2- door wagon
2- door panel delivery
Layout FR layout
Platform GM H platform (RWD)
Engine 140 cu in (2.3 L) OHC 1bbl I4
140 cu in (2.3 L) OHC 2bbl I4
122 cu in (2.0 L) DOHC EFI I4
Transmission 3-speed manual
4-speed manual
5-speed manual w/overdrive
Torque-Drive clutchless manual
2-speed Powerglide automatic
3-speed Turbo-Hydramatic auto.
Wheelbase 97.0 in (2,464 mm)
Length 169.7 in (4,310 mm)
Width 65.4 in (1,661 mm)
Height 51 in (1,295 mm)
Curb weight 2,181–2,270 lb (989–1,030 kg) (1971)
Related Pontiac Astre, Chevrolet Monza, Pontiac Sunbird, Buick Skyhawk, Oldsmobile Starfire
Designer GM & Chevrolet Design staffs
Chief Stylist, Bill Mitchell

Dura-Built 140
Dura-built 140 cu in (2.3 L) 2bbl. I-4, 84 hpThe 140 cu in engine was named Dura-Built 140 in 1976. It featured improved coolant pathways for the aluminum-block, a redesigned cylinder head incorporating quieter hydraulic valve lifters, longer life valve stem seals (which reduced oil consumption by 50%), and a redesigned water pump, head gasket, and thermostat. Warranty on the engine was five years/60,000-mile (97,000 km).[34]

"August 1, 1975. 8 a.m. Outside the southern edge of Las Vegas, Nevada. Three medium orange Vegas start their engines. They won't be turning them off much during the next 58 days except for rest and food stops, refueling and maintenance. They have a job to do."[35] Chevrolet conducted an advertised 60,000 miles in 60 days Durability Run of the 1976 Vega and its Dura-Built 140 engine. Three new Vega hatchback coupes equipped with manual transmissions and air conditioning were driven non-stop for 60,000 miles (97,000 km) in 60 days through the deserts of California and Nevada (Death Valley) using three pre-production models of the subcompact and nine non-professional drivers.

1976 Vegas on the 60,000 miles in 60 days Durability RunAll three 1976 Vegas completed a total of 180,000 miles (290,000 km) with only one "reliability" incident — a broken timing belt. This fact prompted Vega project engineer Bernie Ernest to say, "The Vega has reliability in excess of 60,000 miles, and therefore the corporation feels very comfortable with the warranty." [36]

Motor Trend in their February 1976 report The 60,000-mile Vega, said, "Chevrolet chose the 349-mile Southwestern desert route in order to show the severely criticized engine and cooling system had been improved in the 1976 model. During the 60-day test which was certified and supervised by the United States Auto Club, the three cars were subjected to ambient temperatures never lower than 99 °F (37 °C) and often reaching as high as 122 °F (50 °C). The nine drivers were instructed to treat the cars as they would their own and use the air conditioning as desired. Yet, in more than 180,000 miles of total driving, the cars used only 24 ounces of coolant, an amount attributed to normal evaporation under severe desert conditions. Furthermore, fuel economy for the three test Vegas averaged 28.9 mpg over the duration of the run, while oil was used at the rate of only one quart every 3400 miles. Translated into actual driving expenses, the three Vegas averaged a per-mile cost of 2.17 cents."[37] One of the cars went on display at the 1976 New York Auto Show. The 1976 Vega was marketed as a durable and reliable car.[38][39] The 1977 Dura-Built 140 engine added a pulse-air system to meet the more-strict 1977 U.S. exhaust emission regulations. The engine paint color (as used on all Chevy engines) changed from orange on 1976 engines, to blue on 1977 engines.

[edit] 122 CID DOHC
Cosworth Twin-Cam 16-valve, 122 cu in (2.0 L) EFI I-4, 110 hpThe Cosworth Vega 122 CID engine is a 1,994 cc (121.7 cu in) inline-four featuring a die cast aluminum alloy cylinder and case assembly and a Type 356 aluminum alloy, 16-valve cylinder head with double overhead camshafts (DOHC), designed in conjunction with English engineering company Cosworth. The camshafts are held in a removable cam-carrier which also serves as a guide for the valve lifters. Each camshaft is supported by five bearings and is turned by individual cam gears on the front end. The two overhead camshafts are driven, along with the water pump and fan, by a fiberglass cord reinforced neoprene rubber belt, much like the Vega 140 cu in engine. Below the cam carrier is a 16-valve cylinder head constructed of an aluminum alloy using sintered iron valve seats and iron cast valve seats. Sturdy forged aluminum pistons and heat-treated forged steel crankshaft and connecting rods reveal racing ancestry; assure high performance durability.[40]

The engine features a stainless steel exhaust header and electronic fuel injection (EFI) – a Bendix system with pulse-time manifold injection, four injector valves, an electronic control unit (ECU), five independent sensors and two fuel pumps. Each engine was hand-built and includes a cam cover sticker with the engine builder's signature. The Cosworth Vega engine is some 60 lb (27 kg) lighter than the SOHC Vega engine.[41] The engine develops its maximum power at 5,600 rpm and is redlined at 6,500 rpm where the SOHC Vega engine peaks at 4,400 rpm and all is done at 5,000 rpm. Final rating is 110 hp (82 kW).[42] The planned 1974 launch of the Cosworth variant was delayed when burned exhaust valves were found at 40,000 miles (64,000 km) during a 50,000 miles (80,000 km) emissions certification run. This resulted in a major redesign of the fuel system and ignition system, plus the addition of fresh air injection into the exhaust to reduce pollutants.[43] With only 3,508 of the 5,000 engines used, GM disassembled about 500; the remaining engines were scrapped.[44]

[edit] Aluminum engine block
Vega aluminum engine block has 17 percent silicon content, free standing siamese cylinder wallsGM Research Labs had been working on a sleeveless aluminum block since the late 1950s. The incentive was cost. Engineering out the four-cylinder block liners would save $8 per unit. Reynolds Metal Co. developed an eutectic alloy called A-390, composed of 77 percent aluminum, 17 percent silicon, 4 percent copper, 1 percent iron, and traces of phosphorus, zinc, manganese, and titanium — suitable for faster production diecasting, making the Vega block less expensive to manufacture than other aluminum engines. Sealed Power Corp. developed chrome-plated piston rings that were blunted to prevent cylinder bore scuffing. Basic work had been done under Eudell Jackobson of GM engineering. Then suddenly, Chevrolet got handed the job of putting this sleeveless aluminum block into production. The Vega blocks were cast in Massena, NY at the same factory that had produced the Corvair engine. The casting process provided a uniform distribution of fine primary silicon particles approximately 0.001 inches (25 µm) in size. The blocks were aged eight hours at 450 °F (232 °C) to achieve dimensional stability, then inpregnated with sodium silicate to help eliminate porosity.[2] From Massena, the cast engine blocks were shipped to GM's engine plant in Tonawanda, NY where they underwent the etch and machining operations. The cylinder bores were rough and finish-honed conventionally to a 7-microinch (180 nm) finish then etched removing approximately 0.00015-inch (3.8 µm) of aluminum, leaving the pure silicon particles prominent to form the bore surface. A four-layer plating process was necessary for the piston skirts, putting a hard iron surface opposite the silicon of the block. From Tonawanda, the engines went to the Chevrolet assembly plant in Lordstown, Ohio. The technical breakthroughs of the block lay in the die-casting method used to produce it, and in the silicon alloying which provided a compatible bore surface without liners. With a finished weight of 36 pounds (16 kg), the block weighs 51 pounds (23 kg) less than the cast-iron block of the 153 cu in (2,507 cc) inline-4 used in the Chevy II Nova.

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