This is the O.S. Max .37 SZ-H Ring Helicopter Engine. (Two year limited warranty) FEATURES: Premium performance for 30-sized machines, from extreme aerobatics to stable hovering Same mounting pattern and muffler dimensions as the .32 SX-H, for easy installation in most 30-size helis Re-engineered crankshaft reduces vibration resulting in smooth power across the entire RPM range 20M carburetor with Idle Needle positioned on same side as Main Needle for easier adjustments INCLUDES: One O.S. Max .37 SZ-H Ring Helicopter Engine, with #8 Glow Plug, 20M Carburetor, instruction manual and sticker sheet REQUIRES: Muffler Heli fuel with 10%-30% nitro content SPECS Displacement: 0.37 cu in (6.07cc) Bore: 0.806 in (20.5mm) Stroke: 0.725 in (18.4mm) Practical RPM range: 2000-21,000 Output: 1.4 PS, 1.38 HP @ 18,000 RPM Weight: 10.3oz (293g) Crankshaft Size: 1/4-28 Distance between mounting holes same side: 0.6" (15mm) Distance between mounting holes opposite side: 1.5" (38mm) Width including mounting flanges: 1.8" (45mm) Width neglecting mounting flanges: 1.5" (38mm) Height/bottom of crankcase to top of cylinder head: 3" (76mm) Height/bottom mounting flanges to top of cylinder head: 2.4" (61mm) Distance/center of crankcase to front bearing: 1.8" (46mm) Distance from backplate to front bearing: 2.6" (67mm) Distance from backplate to end of crankshaft: 3.7" (94mm) Low speed needle 1 turn IN from flush with carb body High speed needle 1.5 turns OUT from closed COMMENTS: Drive Washer is not included, if needed order OSMG5506. jxs 9/16/04 updated rda10/10/06 ir/jxs