Thanks to Jon McLin who initially put this page together. Keith Peterson
Our Cardinal is equipped with an aftermarket turbonormalizer system. A "turbonormalizer" is
a turbocharger system where the compressor only functions to maintain sea level
manifold pressure (nominally, 30" Hg) and therefore horsepower. In principle, with a turbonormalizer the engine
is stressed no more than a normally-aspirated engine, and thus TBO is unaffected.
Compressing the air has a side-effect of heating it up. As hot air is less
dense, some power is lost due to this heating. Many turbocharged and turbonormalized
aircraft (and cars and trucks) incorporate an air-to-air intercooler after the
compressor to shed this heat of compression, thus maintaining maximum power. Unfortunately,
the Cardinal installation does not include an intercooler. Because of this, induction air temperatures run perhaps 75° to 100°F above Outside Air Temperature.
The Lycoming IO-360A is rated at 200 HP @ 28.5" Hg of manifold pressure. Because of this rating, the aircraft with the STC has a redline at 28.5" on the manifold pressure gauge. Additionally, the STC includes a placard to "reduce manifold pressure by 1 inch per 1000 feet above 16,000'". This placard is apparently due to an FAA concern that the fuel pump could not adequately draw fuel at altitude, against sea-level pressure. There are reports that the aircraft is capable of developing 28.5" to at least 25,000!
Although TurboFlite no longer exists, the STC has been purchased by and is now available from Tornado Alley Turbo.
The TurboFlite STC incorporates the following major elements:>
- Installation of a Garrett TA04 Turbocharger, 465292-0001/-9001. This turbocharger was originally used in the 78-80 T337 (Turbo Skymaster).
- Installation of an exhaust wastegate and hydraulic actuator (470842-9004) to allow exhaust gas to bypass the turbo. This unit was also used in the rear engine of all turbocharged Skymasters (T337 and P337).
- Installation of an Absolute Pressure Controller (470688-9005) to hydraulically vary the wastegate position based upon turbo compressor output pressure. This controller was used in the Cessna 206, 207, 210, and 310.
- Installation of an oil Scavenge Pump to remove oil from the turbo bearings and return it to the oil sump. This pump is necessary due to the location of the turbo below the engine.
- Installation of fuel injector nozzle "shrouds", which expose the ambient reference ports on each fuel injector to the compressor pressure.
- Connection of the Fuel Flow Gauge reference port to the compressor reference line to correct fuel flow measurements. (Fuel Flow is actually a pressure measurement.)
- Replacement of the stock Stewart-Warner 8406J Oil Cooler with the larger, two-pass Stewart-Warner 8432R Oil Cooler. See the Oil Coolers page for more info.
- Addition of a spin-on oil filter if the aircraft is not yet so equipped.
- "Shark Gills" cooling vents on both sides of the lower cowl. This is how you can identify a Cardinal with the Turbo STC when the cowl is on.
Besides the items listed above, there are numerous hoses, fittings, brackets, check-valves, etc..
Note that, besides the intercooler, TurboFlite chose not to include a pressurized magneto. With the large Bendix dual magnetos on the later Cardinals, this is not a problem. The smaller Slick magnetos on the earlier Cardinals (or those converted back to the non-dual mag design) are susceptible to misfiring due to arcing within the magneto above around 15,000'. Once the arcing occurs, it get progressively worse due to the carbon tracks left inside the magneto. While Slick does make pressurized magnetos for turbocharged aircraft, they are only available for 6-cylinder engines. Therefore, a turbocharged Cardinal should use Bendix magnetos - be they double-single or single-dual.
These pages are a collection of the ideas and impressions of the Cardinal pilots who frequent this site. This information is anecdotal, informal and may not be completely accurate. The Cardinal Flyers are not certified mechanics and do not guarantee the accuracy of the contents of these pages. Please research and confirm anything that is referenced on these pages with the experts appropriate to your situation.
As always, the Cessna maintenance, operations and flight manuals, and the advice of a certified mechanic and flight instructor, should be your primary sources of information regarding safe maintenance and operation of your aircraft.
Copyright Cardinal Flyers Online LLC 1997-2021