| Maker | Isotta Fraschini 750RC | Isotta Fraschini XIR | Isotta Fraschini XIRC40 | Isotta Fraschini Caccia | Isotta Fraschini Astro 7C21 | -- | -- |
| Arrangement | W | V | V | V | Radial | -- | -- |
| Cooling | Liquid | Liquid | Liquid | Liquid | Air | -- | -- |
| No of Cyls | 18 | 12 | 12 | 12 | 7 | -- | -- |
| Bore/Stroke | 5.12" x 6.69" | 5.75" x 6.30" | 5.75" X 6.30" | 4.92" x 5.12" | 6.06" x 6.30" | -- | -- |
| Displacement | 4073 cu ins | 1991 cu ins | 1991 cu ins | 1257.20 cu ins | 1272.2 cu ins | -- | -- |
| Comp Ratio | 5.70:1 | 6.70:1 | 6.40:1 | 5.70:1 | 5.95:1 | -- | -- |
| bmep Cruise | 70 | 103 | 105 | 119 | 110 | -- | -- |
| Blower ratio | 11.46:1 | N/A | 10.70:1 | N/A | 7.65:1 | -- | -- |
| Cyl Material | Steel | Steel | Steel | Steel | Steel | -- | -- |
| Valves per cyl | 2 Inl 2 Exh | 2 Inl 2 Exh | 2 Inl 2 Exh | 2 Inl 2 Exh | 1 Inl 1 Exh | -- | -- |
| Valve Arr. | OHV | OHV | OHV | OHV | OHV | -- | -- |
| HP max - not Take-Off | 900 | 895 | 900 | 480 | 450 | -- | -- |
| @ RPM | 1900 | 2250 | 2400 | 2550 | 2100 | -- | -- |
| @ Altitude | Sea Level | Sea Level | Sea Level | Sea Level | Sea Level | -- | -- |
| HP Take-Off | 850 | Not Given | 860 | Not Given | 420 | -- | -- |
| @ RPM | 1750 | Not Given | 2140 | Not Given | 2000 | -- | -- |
| HP Cruise | 550 | 450 | 500 | Not Given | 320 | -- | -- |
| @ RPM | 1530 | 1740 | 1900 | Not Given | 1800 | -- | -- |
| Fuel Octane | 87 | 87 | 87 | 87 | 87 | -- | -- |
| Prop Drive | Geared | Geared | Geared | Direct | Direct | -- | -- |
| Dry Weight | 1609.4 lbs | 1289.7 lbs | 1322.8 lbs | 840 lbs | 723.1 lbs | -- | -- |
| lb/Cruise HP | 2.92 | 2.86 | 2.64 | 1.75* | 2.26 | -- | -- |
| Carb(s) | 6 X Own | 4 X Own | 4 X Own | 4 X Zenith | 1 X Own | -- | -- |
| Ignition | Marelli Mag(2) | Marelli Mag(2) | Marelli Mag(2) | Marelli Mag(2) | Marelli Mag(2) | -- | -- |
| Starting Method | Own, Comp Air | Own, Comp Air | Own, Comp Air | Own, Comp Air | Own, Comp Air | -- | -- |
| Length | 86.37" | 75.16" | 83.88" | 69.92" | 19.84" | -- | -- |
| Height/O.D. | 47.44" | 40.16" | 42.84" | 31.89" | 47.25" | -- | -- |
| Width | 40.55" | 32.40" | 32.84" | 29.13" | Not Given | -- | -- |
| Bed centres | Not Given | Not Given | Not Given | Not Given | Not Given | -- | -- |
| Mount Dia | Not Given | Not Given | Not Given | Not Given | Not Given | -- | -- |
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.