Turbo-normalizing means the engine holds sea level pressure as it climbs rather than resorting to high turbo boosted pressures (up to 40 inches) with low compression ratio piston configurations like traditional turbochargers. The genius of the turbo-normalized SR22 is that the engine is set up so that the maximum cylinder pressures are at modest levels compared to other installations during full power operation. This results in extremely well controlled engine temperatures, even on hot days in the summer. The routine operation at LOP cruise mixture settings assures you that engine combustion deposits are dramatically lower than other turbo installations and that the routinely model high power cylinder head temperatures enhance engine durability, reducing wear and tear on the engine even as you take advantage of the high speeds the turbo makes possible.
Leaner is cleaner. Leaner is cooler. Cleaner and cooler are better for any engine. Exhaust valves are the critical weak link. They have to get rid of heat. If the cylinder heads are hot, then the exhaust valves can't get rid of their own heat load out through the valve seat, and the extra heat goes up the stems and out to the valve guides (and into the oil flow). The elevated temperature of the valve stem/guide normally shortens the valve stem/guide lifetime dramatically when an engine runs hot.
TURBO TIP For Smart Buyers
Don't get burned – traditional turbocharged engines are notorious for running hot and shock cooling. The engineers at Tornado Alley say it best: "You can't shock cool something that's not hot to begin with." That's the beauty of the turbo-normalized system on the Cirrus SR22. It runs cooler and on much less fuel to get the turbo speed performance that transforms the use of your airplane.
Some turbo installations can make it difficult to access the engine for routine maintenance work on the engine. The turbo system on the Cirrus is one of the cleanest and maintenance-friendly installations in the industry. As one prominent mechanic said when he saw the turbo-normalized SR22 for the first time with its cowling removed, “Wow! This is the first turbo that mechanics are going to want to work on!"
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