Having successfully replaced the engine in November, we purchased the supercharger kit in January and helped our mechanic install it. After persevering through several installation issues, unfortunately the overall value proposition proved unattractive for us. You might come to a different conclusion if flying predominantly above 9000’, or are unconcerned with elevated CHTs, or have a shop handle routine maintenance.
The supercharger continuously saps power and increases intake temperature 60-80F. Consequently, lower altitude (~3000’) cruise is 5 kts slower with 30F hotter CHTs at comparable fuel flow. Capping CHT at 400F as recommended in the DA40 AFM (4A.3.9), climb to 3500’ degrades by 27% (1 min). Climb to 10,500’ is identical. Climb to 11,500’ improves by 4% (40 sec), which considerably undershoots our expectations. Accepting higher CHTs would improve performance, but would also improve normally aspirated (NA) performance up to ~8000’.
Links to flight profiles below, including comparison with a system installed by FAT having similar performance.
Our climb results to 11,500':
The DA40 implementation also adds significant serviceability issues. Unfortunately these were not apparent until installation.
- Routine maintenance requires detaching the spinner (with limited-life self-locking nut plates) and having a helper assist removing the lower cowling. A complicated “dance” hopefully avoids damage to the cowling, spinner bulkhead, propeller and/or port fuselage paint.
Here is a video by Brock of the cowling removal:
- FAT stresses that maintaining supercharger belt tension is critical. Instead of a spring loaded idler pulley, FAT uses a sliding pulley attached with through-bolts. Adjustment requires socket wrenches front and rear (after removing the alternate-air assembly), while a helper braces the propeller and leverages the idler bracket against the starter ring gear. An additional helper to monitor tension with a spring scale is also helpful.
- Accessing or inspecting the starter mounting bolts requires completely removing the supercharger and its mounting bracket.
Here are links to a few flights with/without the supercharger.
~3000’ LOP cruise 5 kts slower & 30F hotter:
- NA: https://apps.savvyaviation.com/flights/ ... c55c3d4561
- Supercharged: https://apps.savvyaviation.com/flights/ ... c5c54bce0d
- NA: https://apps.savvyaviation.com/flights/ ... a07d029160
- Supercharged: https://apps.savvyaviation.com/flights/ ... a74c8cc47e
(N211WP, with supercharger installed by FAT)
The relatively minor differences may be due to:
- Propeller (N211WP's composite 3-blade theoretically climbs better)
- Ambient lift/sink
- OAT about 7C higher for N211WP
- N171CB’s gross weight about 100 lbs higher due to extra fuel, fat pilot & aluminum prop.
- N211WP’s engine is also relatively high time (~2300 hrs), while N171CB’s is newly broken-in (~80 hrs).
- N211WP has electronic ignition, while N171CB does not.