A turbo supercharger is the original name for what we now call a turbocharger. The term dates back to World War I, when engineer Sanford Moss at General Electric built a device that used exhaust gases to spin a compressor, forcing denser air into aircraft engines so they could operate at high altitudes where the air is thin. Over time, “turbosupercharger” was shortened to “turbocharger,” and today the two terms refer to the same thing. Some people also use “turbo supercharger” to describe a twincharged engine that combines a turbocharger and a belt-driven supercharger, though that’s a separate concept entirely.
How the Original Turbosupercharger Worked
Moss’s design was elegantly simple. A centrifugal compressor (called an impeller) sat on one end of a steel shaft, and a turbine wheel sat on the other. Hot exhaust gases from the engine spun the turbine, which spun the compressor, which pulled in outside air and compressed it before feeding it into the engine’s carburetor. No belt, no gears, no direct mechanical connection to the engine’s crankshaft. The energy source was exhaust gas that would otherwise be wasted.
After the U.S. entered World War I in 1917, the government engaged GE and Moss to develop turbosuperchargers for Allied aircraft. The technology proved critical: piston engines lose power as altitude increases because there’s less oxygen in each breath of air the engine takes. By compressing thin high-altitude air back to sea-level density (or greater), the turbosupercharger let planes climb to record heights. The same core design eventually made its way into cars, trucks, and diesel engines, where it became the modern turbocharger.
How a Modern Turbocharger Works
The basic mechanics haven’t changed much since Moss’s prototype. A turbocharger has two main housings connected by a forged steel shaft. On the exhaust side, the turbine housing guides hot exhaust gas into a turbine wheel, spinning it at extremely high speeds. That spinning energy transfers through the shaft to a compressor wheel on the intake side, which draws in fresh air, compresses it, and pushes it toward the engine.
Compressed air is denser air, meaning more oxygen molecules are packed into each cylinder during combustion. More oxygen lets the engine burn more fuel per cycle, producing more power from the same displacement. A small 2.0-liter turbocharged engine can match or exceed the output of a larger naturally aspirated engine while using less fuel under light driving conditions.
Most passenger vehicles run boost pressures between 5 and 15 psi above atmospheric pressure. High-performance and racing applications can push beyond 25 to 30 psi, though that requires reinforced engine internals and more sophisticated tuning.
Pressure Control: Wastegates and Blow-Off Valves
Two key components keep a turbo system from destroying itself. A wastegate sits on the exhaust side and controls how fast the turbocharger spins. It’s essentially a spring-loaded valve: once exhaust pressure exceeds the spring’s rating, the valve opens and routes exhaust gas around the turbine instead of through it. This stabilizes turbine speed and prevents overboosting.
A blow-off valve handles the intake side. When you lift off the throttle, the throttle body snaps shut, but the compressor is still spinning and pushing pressurized air forward. That air has nowhere to go, and the resulting backpressure (called compressor surge) creates stress on the turbo’s shaft and bearings. The blow-off valve senses the sudden vacuum in the intake manifold and opens to vent the pressurized air, protecting the turbo from premature wear. That distinctive “psshh” sound you hear from some turbocharged cars is the blow-off valve doing its job.
Why Compressed Air Needs Cooling
Compressing air heats it up significantly. Hot air is less dense than cool air, which partly defeats the purpose of turbocharging. That’s where an intercooler comes in. Mounted between the turbo’s compressor outlet and the engine’s intake, the intercooler is essentially a radiator for compressed air.
The temperature difference matters more than you might expect. For every 3°C (about 5.4°F) reduction in intake air temperature, oxygen density increases by roughly 1%. In real-world testing on performance vehicles, reducing peak intake temperatures from 60°C down to 25°C yielded close to a 10% power increase. At the extreme end, cooling intake air from 80°C to 30°C can improve oxygen density by over 16%. Even on stock vehicles, the intercooler is doing meaningful work to keep intake temperatures manageable and power output consistent.
Turbocharger vs. Supercharger
The confusion around the term “turbo supercharger” partly stems from the fact that turbochargers and superchargers do the same basic job: compress intake air. The difference is how they’re powered.
A supercharger is mechanically driven, typically by a belt connected to the engine’s crankshaft. This means it responds instantly to throttle input, with no delay. The tradeoff is parasitic loss: the engine has to spend some of its own power just to spin the supercharger. A turbocharger, by contrast, runs on exhaust energy. Its thermal efficiency can reach 55 to 75%, and because it doesn’t steal power directly from the crankshaft, it’s inherently more efficient. The downside is turbo lag, that brief delay between pressing the accelerator and feeling the boost arrive, because the turbine needs exhaust flow to spool up.
In practical terms, superchargers deliver smooth, linear power that builds predictably with engine speed. Turbochargers deliver a more noticeable surge once they reach operating speed but extract more total power from the same fuel. Modern engineering has narrowed the gap considerably: smaller turbos, twin-scroll designs, and electronic wastegates have reduced lag to the point where many drivers never notice it during normal driving.
Twincharging: Using Both at Once
Some engines combine a supercharger and a turbocharger into a single system called a twincharger. This is the other meaning people sometimes attach to “turbo supercharger,” and it’s a deliberate engineering choice to get the best of both worlds.
In the most common setup (called a series arrangement), the supercharger feeds compressed air into the turbocharger’s inlet. At low engine speeds, the supercharger does the heavy lifting, providing near-instant boost and eliminating turbo lag entirely. Once exhaust flow builds and the turbocharger reaches operating speed, the supercharger can be mechanically decoupled from the drivetrain using an electromagnetic clutch and bypass valve. At that point, the more efficient turbocharger takes over, and the parasitic drag of the supercharger disappears.
The result is a lag-free power band with strong torque at low RPM and high power at the top of the rev range. The downsides are added weight, complexity, and cost. Twincharged systems have appeared in production vehicles, most notably from Volkswagen, though they remain relatively uncommon because modern turbocharger designs have gotten good enough at low-end response that the added complexity of twincharging is harder to justify for most applications.
Why the Name Stuck Around
The term “turbosupercharger” made perfect sense in its era. Supercharging, meaning forcing more air into an engine than it could inhale on its own, was already an established concept by the early 1900s. Moss’s innovation was doing it with a turbine instead of a mechanical drive, so “turbo” was simply added as a prefix. As the technology matured and mechanical superchargers became the less common option, the prefix absorbed the whole word. By mid-century, “turbocharger” and then just “turbo” became standard. But the original term still surfaces in aviation history, engineering literature, and the occasional search query from someone who encountered it and wanted to know exactly what it means.