| Maker | Cirrus-Hermes Minor | Napier Dagger Series II | Napier Dagger Series III | Napier Rapier Series V | Napier Rapier Series VI | Pobjoy Niagara IV | R-R Kestrel IV, V, VI |
| Arrangement | Inline | H-6 | H-6 | H4 | H4 | Radial | V 60 deg 12 |
| Cooling | Air | Air | Air | Air | Air | Air | Liquid |
| No of Cyls | 4 | 24 | 24 | 16 | 16 | 7 | 12 |
| Bore/Stroke | 3.74" x 5.00" | 3.8125" x 3.75" | 3.8125" x 3.75" | 3.50" x 3.50" | 3.50" x 3.50" | 3.19" x 3.43" | 5.00" x 5.50" |
| Displacement | 229.6 cu ins | 1027.5 cu ins | 1027.5 cu ins | 538.8 cu ins | 538.8 cu ins | 191.4 cu ins | 1296.0 cu ins |
| Comp Ratio | 5.80:1 | 7.75:1 | 7.75:1 | 7.00:1 | 7.00:1 | 6.50:1 | 6.00:1 |
| bmep Cruise | 95 | 125 | 139 | 109 | 130 | 122 | 119 |
| Blower ratio | N/A | 6.47:1 | 5.04:1 | 6.33:1 | 5.27:1 | NA | 8.83:1 |
| Cyl Material | Steel | Steel | Steel | Steel | Steel | Steel | Steel liner |
| Valves per cyl | 1 Inl 1 Exh | 1 Inl 1 Exh | 1 Inl 1 Exh | 1 Inl 1 Exh | 1 Inl 1 Exh | 1 Inl 1 Exh | 2 Inl 2 Exh |
| Valve Arr. | OHV | OHC | OHC | OHC | OHC | OHV | OHC |
| HP max - not Take-Off | 90 | 755 | 805 | 340 | 395 | 108 | 640 |
| @ RPM | 2600 | 4000 | 4000 | 4000 | 4000 | 3750 | 2900 |
| @ Altitude | Sea Level | 12500ft | 5000ft | 13000ft | 5800 ft | Sea Level | 14000 ft |
| HP Take-Off | 75 | 710 | 760 | 335 | 365 | 95 | 700 |
| @ RPM | 2200 | 3500 | 3500 | 3500 | 3500 | 3400 | 2500 |
| HP Cruise | 63 | 565 | 630 | 260 | 310 | 100 | 485 |
| @ RPM | 2300 | 3500 | 3500 | 3500 | 3500 | 3230 | 2500 |
| Fuel Octane | 70 | 87 | 87 | 87 | 87 | 70 | 87 |
| Prop Drive | Direct | Geared | Geared | Geared | Geared | Geared | Geared |
| Dry Weight | 195 lbs | 1280 lbs | 1280 lbs | 713 lbs | 713lbs | 164 lbs | 955 lbs |
| lb/Cruise HP | 3.1 | 2.27 | 2.03 | 2.75 | 2.30 | 1.64 | 1.97 |
| Carb(s) | 1 X Claudel | 1 X Claudel | 1 X Claudel | 1 X Claudel | 1 X Claudel | 1 X Claudel | 1 X R-R Own |
| Ignition | BTH Mag(2) | BTH Mag(2) | BTH Mag(2) | BTH Mag(2) | BTH Mag(2) | Rotax Mag(2) | BT-H/Watford Mag(2) |
| Electric Starter | BTH | Rotax Inertia | Rotax Inertia | Rotax Gas/Hand | Rotax Gas/Hand | Rotax | Own Hand |
| Length | 37.72" | 80.00" | 80.00" | 57.37" | 57.37" | 22" | 72.35" |
| Height/O.D. | 25.00" | 45.12" | 45.12" | 37.00" | 37.00" | 27.50" | 35.00" |
| Width | 16.50" | 23.00" | 23.00" | 21.62" | 21.62" | NA | 24.40" |
| Bed centres | 15.20" | 17.12" | 17.12" | 18.50" | 18.50" | 19.75" | 17.25" |
| Mount Dia | NA | NA | NA | NA | NA | NA | NA |
Let me know if any of the above does not read true, or if you have information that does not agree. Wherever possible, I will update these pages on a regular basis as data comes in.