This is the GT33 Gasoline Aircraft Engine with Muffler and Rear Carburetor from O.S. Engines. FEATURES: Electronic ignition accepts LiFe, LiPo, NiCd and NiMH power and also offers low voltage warning Rear mounted Walbro carburetor-NOTE the choke valve rod shown on page 12 of the manual is not included Pitts style E-5030 aluminum muffler black in color, 5dB lower in noise than the competition Two year limited warranty through Hobby Services beginning at date of purchase INCLUDES: GT33 Gasoline Aircraft Engine with Muffler, Carburetor, CM-6 Spark Plug and Instruction Manual REQUIRES: 2-cycle oil, see SPECS Ignition Battery: 4.8-6.0V NiCd or NiMH, 6.6V LiFe or 7.4V LiPo pack LiPo battery requires voltage regulator Propeller: 18x10-12, 19x10, 20x8-10, use 18x8 prop for break-in Mounting standoffs, length depends on aircraft Gasoline safe fuel tubing and fuel filter SPECS: Displacement: 2.013 cu in (32.98cc) Bore: 1.417" (36mm) Stroke: 1.276 (32.4mm) Crankshaft thread size: 5/16-24 Total Weight: 2.7lbs (1230g) Engine, 34.72oz (984g) Muffler, 5.65oz (160.5g) Ignition: 3.70oz (105.0g) RPM Range: 1,800 - 8,000 Output: 3.9 PS, 3.85 HP/9,000rpm Gasoline/Oil Mixture: 30:1 - 50:1 25:1 fuel/oil mixture if brand of oil states 50:1 mix Replacement Spark Plug: NGK CM-6 or Denso U20M-U Height, Crankshaft Center to Exhaust Outlet: 6.1" (156.1mm) Height, Crankshaft Center to Muffler Body: 4.1" (105.4mm) Height, Crankshaft Center to Muffler Mounting Holes: 2.1" (54.4mm) Height, Crankshaft Center to top of Cylinder Head: 4.3" (109.2mm) Length, end of Crankshaft to Carb: 7.7" (196.6mm) Length, end of Crankshaft to Backplate: 6.2" (158.9mm) Length, end of Crankshaft to Center of Engine: 4.9" (125mm) Length, Prop Washer to Center of Engine: 3.3" (84.5mm) Length, Prop Washer to Carburetor: 6.1" (156.2mm) Length, Prop Washer to Backplate: 4.7" (118.5mm) Width, Muffler Body: 4.5" (114mm) Width, Crankshaft Center to Exhaust Outlet: 1.2" (31.5mm) Cylinder Head Diameter, front to back: 2.5" (62.8mm) Cylinder Head Diameter, side to side: 2.6" (66mm) Mounting Hole Centers top to bottom: 2.1" (54mm) Mounting Hole Centers side to side: 3" (76mm) jxs 04/28/11 ir/jxs updt jxs 11/11/11