Falling fuel prices, bigger engines and maintenance worries all but wiped out the turbocharger market in the early 1990s. But now automakers are showing renewed interest. Meanwhile, suppliers have been working on a better mousetrap. Among the improvements made or in development:
Components reduced by 70 percent.
Turbine housing and exhaust manifolds made as a single casting to prevent sealing problems.
Aerospace air bearings used to prolong bearing life. They use thin, overlapping sheets of Teflon-coated metal that spread apart to leave a tiny film of air to cushion the spinning shaft.
Variable-nozzle turbos with computer-controlled inlet vanes to make turbos more responsive at lower engine speeds and more efficient at higher speeds.
Electric-motor assist to eliminate 'turbo lag,' the brief hesitation that occurs as exhaust gas pressure builds up.
Hydraulic turbos use pressurized fluid instead of exhaust gas, giving engine designers more freedom in packaging turbos under the hood.