A bullish band of Floridians is determined to link Miami, Orlando and Tampa some day with a 160-mile-per-hour passenger train. Basic to their dream is the assumption that motorists will abandon their cars and flock to high-speed trains in large enough numbers that the system will turn a profit.

Planners foresee tourists and commuters being whisked the 230 miles from Miami International Airport to Orlando's jetport in an hour and 20 minutes. In another half hour, the train would speed the 90 miles from Orlando to Tampa. They say the system would help relieve pressures on roads and air routes brought about by the anticipated doubling of the state's population in 30 years.

A high-speed rail system in Florida could spur development of a network of bullet trains extending north to Atlanta and Washington and west to New Orleans, Houston, Dallas and Fort Worth, according to John Parke Wright IV, the visionary businessman appointed by Gov. Bob Graham to head the Florida High Speed Rail Committee. Wright is president of Lykes International of Tampa and vice president of Lykes Brothers Inc., Florida's largest citrus and beef concern.

All the fuss over a bullet train, whose cost estimates range from $3 billion to $6 billion, has attracted attention from firms in five countries. A team of engineers from a subsidiary of Japan National Railways will complete a feasibility study for the project next month, with a ridership study to follow at a total cost of $1 million. French firms announced in early April that they will do a similar study and the Canadian firm Bombardier Inc. is expected to finish a study in June. West German firms, in cooperation with Michigan-based Budd Co., also are interested, as are the British.

So far the Japanese are thought to have the edge on providing the railroad equipment, by virtue of their ties with American High Speed Rail Corp. and with Lykes' beef and citrus trade. Wright has asked the Japanese for $2 billion at 4 percent interest for a 40-year term to build the Tampa-Orlando leg. Although he hasn't received a response, he suggests the Japanese will come through in part to compensate for the $20 billion trade surplus Japan enjoys over the United States.

Wright, who said he was won over to Japan's rail system during a 12-year stint in the Far East, is convinced that Florida will have a bullet train some day.

"It's not a question of if it will be built, the key question is when," insists Wright, who believes rail provides the only alternative to relieve state overcrowding. "If you're doubling the population, you're going to double the congestion that is already quite bad in some of these cities, so the alternative is to sit back and do nothing but build more highways and create another Los Angeles."

Florida is ideal for high-speed rail construction because it has straight, relatively unpopulated highway rights-of-way that could be used for trains, Wright said. He predicted the bullet train would spur development of the state's interior, relieving pressure on the already crowded coastal areas.

Wright also is talking with Budd Co. officials about the possibility of constructing a magnetically levitated demonstration train that would shoot tourists from Disney World in Orlando to Cape Canaveral in nine minutes. Budd has exclusive rights to the so-called "Maglev" technology, developed by its West German sister company, Thyssen Henschel. The technology enables trains literally to "fly" four inches above the track on a magnetic cushion.

High-speed trains are particularly well-suited to fill a transportation niche in densely populated 100- to 300-mile urban corridors, according to several experts who testified before a House transportation panel last fall. Cars would be more desirable for shorter distances, airplanes for longer distances, experts said.

Lawrence D. Gilson, president of American High Speed Rail Corp., which is cooperating with the Japanese on the Florida study, is a cautious believer in the bullet train for that state at some time in the future. But said Gilson, a former vice president of Amtrak, "We're just not at the point where I can say it's a do-able deal."

Kinji Suzuki, head of the Bank of Tokyo's Miami office, said he has a "keen interest" in the project, but that he will make no decisions until after the feasibility study is completed.

Some analysts are downright gloomy. "It seems to me the numbers involved in building such a system are prohibitive," said Eliot Fried Jr., a transportation analyst with Shearson-American Express. "The general belief is that on a return-on-capital basis it would be absolutely insane to invest in it."

Some high-speed railways do make money. Japan's Shinkansen train on the 320-mile Tokyo-Osaka route earned $1.3 billion in 1978, and is said to have been profitable since 1966, two years after it was built.

A group of U.S. and Japanese firms is now attempting to raise $2 billion to build high-speed rail service between San Diego and Los Angeles. That 130-mile route has the most potential to turn a profit of any rail corridor in the country, according to an Amtrak study published in 1981. American High Speed Rail, builder of the system, has chosen to use Japanese rail technology and has a commitment from the Bank of Tokyo to seek $500,000 in Japanese funding.

The California legislature has approved $1.25 billion in tax-exempt bonds to fund the railway, which is expected to be used heavily by commuters who now travel by car.

But Florida's situation is different. Although there is considerable commuter pressure on roads near Miami, there is not a heavy flow between Miami and Orlando. Nor does Florida have California's population density. Wright estimates that 30,000 persons would have to ride the train each day for it to make money. But only 1,200 peersons a day flew between Miami and Orlando last year, according to the Civil Aeronautics Board.