The Twin Cam Test Drive – It gets them every time.

8 Jun

The Chevrolet Cosworth Vega is a subcompact four-passenger automobile produced by the Chevrolet division of General Motors for the 1975–’76 model years. The Cosworth Twin-Cam is a limited production, performance version of the Chevrolet Vega. Its purpose was to “create excitement for the entire Vega line.” The production version of the Cosworth Vega twin-cam engine was developed by Chevrolet with the cylinder head design by Cosworth Engineering in England. The vehicle was introduced to the public at the Chicago Auto Show in February 1975. The all-aluminum 122 cu in inline-four engines were hand-built at GM’s Tonawanda engine plant — each signed by the engine builder. “Cosworth. One Vega for the price of two” was only $900 less than the 1975 Corvette. 5,000 engines were built, but only 3,508 cars were produced in 18 months.

History
Racing origin

In a hand-written August 1969 memo, John DeLorean, then Chevrolet’s general manager and vice-president of General Motors suggested Jim Musser, Vega project leader to contact Cosworth Engineering racing experts in England to see if they’d be interested in transforming Chevy’s new aluminum-block into a 300-hp racing engine.
Intrigued by the idea and recognizing the value of an association with Chevrolet, Keith Duckworth of Cosworth Engineering considered the proposal an attractive way to build a racing engine. He promptly visited the States to examine the new Vega block closely. Impressed by its sound structural concepts and logical lines of stress from top to bottom, he was overheard to say, “You couldn’t easily see where it was likely to break first.” Duckworth decided that Cosworth was interested, and a dialog with Chevrolet’s engineers began in 1969.
Cosworth EAA

Chevy-Cosworth EA raced 1999-2005 in Lola T292

The Cosworth racing engine based upon the Vega aluminum block was known internally at Cosworth Engineering as Project EA. The EA engine produced a reported 260 hp. Installed in Chevron and Lola chassis, it proved the fastest in the 2-liter class in its first outings. During the year that followed, Cosworth of England experienced repeated catastrophic failures of the engine blocks—they had an unhealthy propensity to split horizontally below the cylinder bores. Chevrolet later offered heavy duty blocks but by then Cosworth had bowed out of the program.

Chevrolet pursued a diverging path toward a streetable version of the twin cam cylinder head design, seeking a reliable engine that developed lots of power. Lloyd Reuss, then Assistant Chief Engineer at Chevrolet, decided that a streetable version of the Cosworth engine would be the hot ticket to improving the Vega’s image and Chevrolet’s sporting image as well.
The ZO9 Cosworth Vega is a direct derivative of the EA racing engine. Although it has been widely thought of by the general public as a souped up Vega engine, it is in truth a de-tuned EA racing engine. It lacks the EA’s dry sump lubricating system (neither necessary nor desirable for passenger car application), has a lower compression ratio and different valve timing and uses Bendix electronic fuel injection in place of the Lucas mechanical injection, but bore, stroke and valve sizes are identical. The Bendix injection is actually more sophisticated than the Lucas since it has to cope with a wider range of operating conditions as well as emission controls.

http://chevyvega.wikia.com/wiki/Chevrolet_Cosworth_Vega

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