Check the listing for details. NEW IN BOX HB .61 PDP AERO ENGINE WITH MUFFLER. Condition: New. Listed at 219.99 USD. The HB .61 is a renowned engine for durability and performance. It was used by the US Army to power target drones in the 1980's. Its light weight and high power make it a favorite for many modelers. The patented PDP ports boost the power without increasing fuel consumption. These 4 finger ports are located on the exhaust side of the baffle and introduce an additional fuel charge in a normally dead area of a loop scavenged engine design. SPECIFICATIONS HB .61 HB .61 PDP HP * 1.45 @ 16,000 RPM 1.85 @ 16,000 RPM Practical RPM * 1800 ~ 16,000 1800 ~ 19,000 Porting Arrangement Loop Scavenged Loop Scavenged with PDP ports Displacement .61 cu. in. (9.97 ccm) Bore & Stroke 0.944" x 0.866" Prop Shaft Thread 1/4 x 28 Piston/cylinder type Dykes ring piston / hardened steel liner Connecting Rod Forged Aluminum bushed at both ends Crankshaft One piece hardened Steel Engine Weight 14.6 oz. (413 gr.) Muffler Weight Bearings Double Ball Bearing supported crankshaft Carburetor O-ring sealed twin needle with full fuel metering, composite body. Carburetor neck Dia .510" Dia HB is Manufactured by MECOA Model Engine Company of America with US and German componets. HB Is a registered trademark of MECOA Reg USPTO