This is the O.S. Max .55 AX Aircraft Engine with Muffler.

FEATURES: Same mounting dimensions as the O.S. Max .46 AX
                   Advanced Bi-Metallic Liner process uses a double layer of plating material rather than one thick layer. This helps the metal bond to the cylinder and makes the plating more durable. Also, the plating process is more consistent, resulting in a more precise fit between piston and sleeve for better compression and longer life.
                    Angular head design offers increased surface area for better cooling 40J carburetor with diagonally placed needle valve eliminating remote needle valve placement.

INCLUDES: O.S. Max 55 AX ABL Aircraft Engine with E-3070 Muffler, 40J carburetor, #8 glow plug, illustrated instruction manual, 3.5\" (90mm) long needle valve extension cable and two 3x35mm muffler screws.

REQUIRES: Aircraft blend fuel containing 5%-20% Nitromethane with at least 18% lubricant.

SPECS:    Displacement: 0.545 cu in (8.93cc)
                   Bore: .906 in (23mm)
                   Stroke: 0.846\" (21.5mm)
                   Practical RPM: 2,000-17,000
                   Power Output: 1.75 ps/16,000 RPM
                   Weight: 14.29oz (405g) w/o muffler
                                 18.52oz (525g) w/ muffler
                   Recommended Props: 12x7-8, 13x6-7
                   Crankshaft thread size:1/4-28
                   Distance/remote needle to end of crankshaft:          4.7\" (119.4mm)
                   Distance from center of engine to drive hub:          2.4\"  (60.4mm)
                   Distance from center of engine to end of crankshaft:  3.4\"  (87.6mm)
                   Distance/crankshaft center to muffler exhaust outlet: 3.9\" (100.5mm)
                   Height from crankcase bottom to top of cylinder head: 3.3\"  (85.2mm)
                   Height/crankshaft center to top of cylinder head:     2.6\"  (67.4mm)
                   Width including mounting tabs:                        2\"    (51mm)
                   Width not including mounting tabs:                    1.4\"  (35mm)
                   Width between mounting holes same side:               0.69\" (17.5mm)
                   Width between mounting holes opposite side:           1.7\"  (44mm)\"
                   Diameter of muffler body:                             1.5\"  (38.1mm)
                   Angle of muffler in relation to engine:               4°

COMMENTS: Available Pitts Mufflers include Bisson O.S. .46 SF/FX .50 SX Pitts Muffler and Slimline Pitts Muffler O.S. .40-.46 SF/FX.