In aircraft engines, turbocharging is commonly used to maintain manifold pressure as altitude increases (i.e. to compensate for lower-density air at higher altitudes). Since atmospheric pressure reduces as the aircraft climbs, power drops as a function of altitude in normally aspirated engines. Systems that use a turbocharger to maintain an engine's sea-level power output are called turbo-normalized systems. Generally, a turbo-normalized system attempts to maintain a manifold pressure of 29.5 inHg

My best guess is turbocharged to bring pressure at the carburetor to atmospheric pressure at sea level (1 atm.). So, you're not putting much more stress on the engine than it would get without the turbo at sea level, but you get constant engine performance up to a good altitude.