| Maker | Lycoming R-680- D5 | Lycoming R-680- D6 | Lycoming R-680- E1 | Lycoming R-680- E2 | Lycoming R-680- E3 | Menasco Pirate C4 | Menasco Pirate C4S |
| Arrangement | Radial | Radial | Radial | Radial | Radial | Inverted In-Line | Inverted In-Line |
| Cooling | Air | Air | >Air | Air | Air | Air | Air |
| No of Cyls | 9 | 9 | 9 | 9 | 9 | 4 | 4 |
| Bore/Stroke | 4.625" x 4.5" | 4.625" x 4.5" | 4.625" x 4.5" | 4.625" x 4.5" | 4.625" x 4.5" | 4.75" x 5.125" | 4.75" x 5.125" |
| Displacement | 680 cu ins | 680 cu ins | 680 cu ins | 680 cu ins | 680 cu ins | 363 cu ins | 363 cu ins |
| Comp Ratio | 6.50:1 | 5.50:1 | 6.20:1 | 5.50:1 | 7.00:1 | 5.50:1 | 5.50:1 |
| bmep Cruise | 122 | 113 | 122 | 116 | 129 | 105 | 121 |
| Blower ratio | 1.0:1 | 1.0:1 | 1.0:1 | 1.0:1 | 1.0:1 | N/A | 9.60:1 |
| Cyl Material | Steel | Steel | Steel | Steel | Steel | Steel | Steel |
| 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 | 1 Inl 1 Exh |
| Valve Arr. | OHV | OHV | OHV | OHV | OHV | OHV | OHV |
| HP max - not Take-Off | 245 | 225 | 275 | 265 | 285 | 125 | 150 |
| @ RPM | 2100 | 2100 | 2200 | 2200 | 2200 | 2175 | 2260 |
| @ Altitude | Sea Level | Sea Level | Sea level | Sea Level | Sea Level | Sea Level | 3000ft |
| HP Take-Off | 260 | 245 | 290 | 280 | 300 | 125 | 158 |
| @ RPM | 2300 | 2300 | 2300 | 2300 | 2300 | 2175 | 2250 |
| HP Cruise | 210 | 195 | 210 | 200 | 222 | 95 | 112 |
| @ RPM | 2000 | 2000 | 2000 | 2000 | 2000 | 1975 | 2025 |
| Fuel Octane | 80 | 73 | 80 | 73 | 87 | 73 | 73 |
| Prop Drive | Direct | Direct | Direct | Direct | Direct | Direct | Direct |
| Dry Weight | 505lbs | 505lbs | 514lbs | 514lbs | 514lbs | 284lbs | 299lbs |
| lb/Cruise HP | 2.4 | 2.59 | 2.45 | 2.57 | 2.31 | 2.99 | 2.67 |
| Carb(s) | 1x Stromberg | 1x Stromberg | 1x Stromberg | 1x Stromberg | 1x Stromberg | 1x Stromberg | 1x Stromberg |
| Ignition | Scintilla Dual Mag | Scintilla Dual Mag | Scintilla Dual Mag | Scintilla Dual Mag | Scintilla Dual Mag | Bendix Mag | Bendix Mag |
| Electric Starter | Eclipse | Eclipse | Eclipse | Eclipse | Eclipse | Eclipse | Eclipse |
| Length | 37.047" | 37.0472" | 37.047" | 37.047" | 37.047" | 47.531" | 47.531" |
| Height/O.D. | NA | NA | NA | NA | NA | 28.562" | 28.562" |
| Width | 43.50" | 43.50" | 43.50" | 43.50" | 43.50" | 17.781" | 14.50" |
| Ht above bed | NA | NA | NA | NA | NA | NA | NA |
| Mount Dia | 19.25" | 19.25" | 19.25" | 19.25" | 19.25" | 16.625" | 16.625" |
Let me know if any of the above does not read true, or if you have other information that does not agree.
Wherever possible, I will update these pages on a regular basis as data comes in.