A small group of student engineers at Virginia Polytechnic Institute has organized "Expo '81: A Technology Showcase," which takes place at Virginia Tech this Wednesday and Thursday. Without any administrative help or funding from the college, the students have attracted more than 75 major corporations and industries to participate in the event, which planners hope will become an annual, student-run affair.

Headed by Joseph Wiencko, president of the Student Engineers' Council, and council publicity director Eric Owens, the group of about 20 students charged each participant a "modest fee" enabling them to bring a display and representatives to the two-day showcase. Many of the exhibits will show the exhibitors' latest technological achievements or what the future holds for that particular field. The purpose of the event, planners say, is "to promote student-industry contact."

Among the Expo '81 participants from the Washington area are: Aberdeen Proving Ground, Atlantic Research, Black & Decker, the C.I.A., National Security Agency, Reynolds Metals, the Nuclear Regulatory Commission and Vepco. Other well-known companies, including Union Carbide, Texaco, Exxon, GE, Dow Chemical, IBM, Monsanto and Weyerhauser, will also attend.

A talking computer, a color graphic terminal and a light-fiber display are just a few of the many exhibits slated for the exposition, which is free and open to the public. Industry representatives will be on hand to explain their exhibits and answer questions concerning job opportunities within their organizations.