From: George Braly <gwbraly@gami.com>
Date: December 20, 2009 2:50:57 AM EST

>>Here's another thought:  A lot of it might depend on your intended usage.  If you want to go really high (over 20K) and have maximum performance you might want to consider getting the extra power of the TSIO-550.  But if you, like me, might limit altitudes to less than 20K and are more cost and fuel economy sensitive, then a lower tech solution might be in order.  I flew for many years behind a Lycoming O-540 that was turbonormalized (C-TR-182) and it worked quite well.  It didn't have an intercooler or automatic waste gate - the waste gate was connected to the throttle linkage so there were no extra levers.  It was fed by a pressurized carburetor, so that doesn't apply with a Continental.  So the question is, what's wrong with using a standard IO-550 with a turbo and manual waste gate?  The Lycomings don't bother with a sniffle valve, so there isn't any difference between turbo, fuel injected, or naturally aspirated engines in that regard.  At 18,000 feet the use of an aftercooler has real, but marginal benefit, as the extra aerodynamic drag and pressure loss negate most of the charge-cooling benefit.  Just a thought, suggesting a KISS methodology.
Gary<<