This is the Novarossi Rex 91HR 3D - V2 8-Port Standard Plug Helicopter Engine, with an H9 491 Tuned Pipe combo. With many prototype iterations, Novarossi has designed a completely new 3 Needle carburetor to take Novarossi helicopter engines to a new level of performance. This new 3 Needle carburetor will provide optimum tuneability, power and performance, and is easier to tune when you're trying to extract all the power from the engine. This is achieved by using a thermal insulator on the carburetor bushing that insulates the carburetor body from crankcase heat, to help reduce the possibility of vapor-lock. A "Dykes" type piston ring has been used to improve the sealing between the piston and the cylinder, the sleeve has 8 transfer ports and is made from high quality iron, and the back plate has been optimized to reduce the dead space inside the crankcase.

Features:

• V2 Cooling Head: The V2 cooling head of the R91HR 3D V2 engine is made from aluminum that is been chosen for its heat conducting capacity. The New R91HR 3D V2 cooling head is "Carb-Smart" ready and has a new shape to fit perfectly into any heli cooling shroud.
• Piston Ring: The "Dykes" type piston ring has been implemented to improve the sealing between the piston and the cylinder.
• Connecting Rod: The connecting rod is made from a super light aluminum which has been ultrasonically checked to prevent premature failures. The specific form creates little turbulence inside the engine which aids the internal gas-flow.    
• Sleeve: The sleeve has 8 transfer ports and is made from iron.
• Crankcase: The crankcase is made from a special alloy, developed by Novarossi to achieve the best possible strength to weight ratio. This crankcase is made to standard dimension in order to fit most helicopters.    
• 3 Needle Carburetor: This engine has an carburetor with an rotary throttle valve and comes with a 11mm body. It features a simple Min/Med/Max mixture adjustment.
• V2 Edition Rear Cover: V2 Rear Cover was redesigned to allow the Spektrum RPM sensor installation and is compatible with previous REX 91 HR 3D engine edition.
• Crankshaft: The crankshaft is made from high quality steel and is available in Turbo 5/16" x 24 version.
• Rear Ball Bearing: The rear ball bearing of this engine is made from high quality steel.    
• Combustion Chamber: This combustion chamber has a semi spherical shape, in combination with the centered glow plug, Novarossi has created the most effective combustion process possible.
• Glow Plug: Standard Heli Glow Plug. All brands of Heli Glow Plug can be used. Medium/Hot and Hot Plugs are advised.