One of the most powerful engines from OS, the GF40 is a 4-stroke gasoline engine. Its quick response makes it an excellent choice for aerobatic models. If you are a scale model pilot, you will also benefit from the deeper exhaust sound of the GF40; similar to that of full-size aircraft. This OS engine has the same mounting bolt pattern and mount-to-drive hub of the GT33. Its fuel economy is excellent; running on a mixture of engine oil and standard gasoline. The GF40 also features a Postive Crankcase Ventilation (PCV) system, which recirculates blow-by gas and oil waste. This is not only environmentally-friendly, but makes the engine cleaner. Additionally, the GF40 comes with an F-6040 silencer and integral backplate. If you are a scale or aerobatic pilot, the GF40 from OS Engines is a great investment that will deliver excellent benefits to your model. Order yours today.