This is the Thunder Tiger .28 cu in (4.5cc) ABN Airplane Engine with Muffler. FEATURES: One piece crankcase with carburetor body and backplate ABN construction-"A"luminum piston with a "B"rass cylinder that is "N"ickle plated Swept back needle valve placement keeps fingers away from spinning propeller Three chamber muffler for quieter noise levels and lower fuel consumption Three year limited warranty INCLUDES: Thunder Tiger .28 cu in (4.5cc) ABN Engine with Muffler, glow plug, combination wrench, muffler screws and instruction manual REQUIRES: Fuel: Airplane blend with 5-15% nitromethane content and 20% lubricant Propeller: 9x6 for break-in, 9x6, 10x5 for stunt or aerobatic flight Field Equipment: Glow starter, fueler, plug wrench and more SPECS: Bore: 0.736" (18.7mm) Stroke: 0.65" (16.5mm) Practical RPM: 2,500-17,000 Output Power: BHP 0.7, RPM 16000 Weight without Muffler: 7.80oz (221.1g) Distance from Prop Washer to Center of Engine: 1.87" (47.4mm) Distance from Prop Washer to Backplate: 2.71" (68.8mm) Distance from Backplate Bottom/top of Cylinder Head: 3.37" (85.7mm) Distance from Mounting Tab/top of Cylinder Head: 2.44" (61.9mm) Center of Mounting Holes Same Side: 0.55" (14mm) Center of Mounting Holes Opposite Side: 1.42" (36mm) Width of Backplate Beneath Mounting Tabs: 1.17" (29.6mm) Width of Upper Section of Backplate: 1.85" (47mm) Distance Between Upper Backplate Mounting Hole Centers: 1.52" 38.5mm Distance/Upper Mounting Holes to Lower Mounting Hole: 1.13" (28.7mm) jxs 2/19/08 ir/jxs