The automotive gas turbine, a close cousin of the airplane jet engine, is coming on strong as a potential replacement for at least some conventional reciprocating gasoline engines, according to technical people at a Departmentof Energy contractors meeting here today.

The turbine was a pronounced dark horse in alternative engine discussions just six years ago. It is now one of just two powerplants getting the bast majority of attention by the government as well as the auto companies.

The other is the Stirling engine, according to George Thur, chief of Heat Engine Systems at the Dept. of Transportation Energy Conservation Division.

Since the 1970 Clean Air Act directed the government to fund research in alternative automotive power plants, the steam car, the electric automobile and assorted other systems have been the object of federal study.

All but the as turbine and Stirling have fallen by the roadside, at least in the eyes of the government.

Even the stratified charge modification of the conventional engine was dropped "because it could not meet the statury (emmission) standards without a severe fuel economy penalty," Thur said.

The traditional drawbacks to the gas turbine in automobiles have been the high cost of making it, the expensive materials required by its high operating temperatures, and poor fuel consumption.

A loud jet engine-like whine and a nagging lag in throttle response are two strong criticisms that have largely been overcome in recent years.

On the plus side for the gas turbine are its multifuel capacity, speed of start in cold weather, generally trouble-free operation and light weight. The gas turbine also has consistently low emissions that result from its continuous combustion.

"The gas turbine has a bit of a credibility problem - to date it has been a lot of promise, a lot of talk," said Charles Wagner, project manager of Chrysler Corp's federally-funded work.

The number three automaker showed a gas turbine powered Chrysler LeBaron at the meeting here, but acknowledged the vehicle still falls short of its goals. The targets include a 15.2 mpg city rating, a 27.5 mpg highway rating and a composite of 19.0 mpg all with diesel fuel.

The up-graded Chryler gas turbine is intended to yield 120 horsepower and move the nearly 3.660-pound car from 0 to 60 miles per hour in 13 seconds.

Wagner said he expects to see such results in the test vehicle next spring. A large part ofChrysler's current effort involves shrinking the size ofthe gas turbine to reduce its size in parallel with shrinking car sizes, he said. The federal government has been funding Chrysler's turbine work at about $3 million a year for some five years.

Asked what the cost of producing the gas turbine might be, Wagner guessed it would require "almost a $2,000 price premium." He said one Chrysler manufacturing expert estimated after three months of study that cost could perhaps be cut in half.

The key is fuel economy, Wagner said. "For 1985 it needs to be 50 per cent better than a reciprocating engine or it wouldn't be worth tooling up for," he said.

In an automobile the gas turbine is now an anomaly. Under study operation and with a fairly heavy load, it yields good to superb fuel economy. The problem is that at idle a gas turbine gulps fuel - burning up to half as much while stopped at a stop light as it would at 90 miles per hour.

Thats one reason General Motors is giving serious consideration to putting the gas turbine into a car that would be sold specifically as a long distance, freeway vehicle.

William Agnew, technical director of GM's Research Laboratories, said in a recent interview that if the gas turbine were limited to "high-speed cruise conditions, its fuel economy looks pretty good."

in an interstate vehicle, its fuel economy "might very well be competitive in large cars." Agnew said.