Metro General Manager Richard S. Page tried to sell Congress his ambitious program to speed completion of the 101-mile Metro subway system yesterday, emphasizing that a speed-up is necessary for Metro to be built for the money available.

If Metro follows its present schedule, Page said, the cost of completing the 101-mile system could exceed $8 billion, about $250 million more than is available under the Metro funding bill that passed Congress and was signed by President Carter late last year.

That bill -- which authorized $1.7 billion in federal funding to complete Metro -- assumed a 7 percent annual inflation rate. Yesterday's new Consumer Price Index report said that inflation in February occurred at an annual rate of almost 18 percent.

Page's proposal to speed up construction -- which would require $140.5 million more in federal aid for 1981 than the Carter administration has budgeted -- met with a cool reception at best.

Rep. Adam Benjamin Jr. (D-Ind.), who was acting as chairman of the House Appropriations Transportation subcommittee yesterday, asked Page if the funding request was a "realistic expectation" in light of the present mood in Congress to cut the budget, not add to it.

"I am making the request," Page said, because it offered a construction program that is "faster and more efficient." However, he said, "I know the program is ambitious, and not fully consistent with the President's budget."

The Carter Administration has budgeted $275 million in 1981 for Metro construction; Page was asking for $415.5 million.

Page and his construction chief, John Egbert, first proposed the speed-up schedule in December. It would result in Metro being completed in 1989 instead of 1990, Page said.