The Ultimate Engines M-4R is a 4 port engine with tuned crankshaft and represents the most powerful and fast 1/8 off-road engine of the Ultimate Engines line. The Modelix Racing R&D team worked hard to develop an engine that takes what they learned from the M-5 and M-8 to further improve fuel mileage, reliability, and overall performance. The M-4R has all what an engine needs to compete against other market leading engines, but at a price point that is well below what you normally will pay for a top quality race engine.
The M-4R is designed by Modelix Racing and built by Novarossi.
Cooling Head: The cooling head for the M-4R is new design first implemented in 2015. The Modelix team specifically went with an oversized head to help keep the engine running cooler and improve performance when running at higher temperatures. Although it is oversized, it’s drilled and milled to make it light and to keep the overall center of gravity of the engine low.
Another change from the previous design is the diameter of the central hole of the head where the glow plug fits is reduced. For those that use temperature guns to measure engine temperature this will give you a more accurate reading because the gun will not factor the temperature of the plug in with the overall engine temperature since the plug is not easy to “see.”
Carburetor: The carburetor chosen for the M-4R engine is the plastic one from Novarossi. It is a "reverse" type with a sliding throttle valve. It provides high idle stability, more precise tuning and higher mid/top range power.
Crankshaft: The exclusive 13mm turbo crankshaft is also designed by the Modelix team and is hand tuned and lightened to allow your engine to change RPM more quickly. It is surprisingly strong and reliable thanks to the special steel material Modelix uses and the heat treatment process the crankshaft goes through.
Backplate: The shape of the rear cover reduces dead space, thereby optimizing the filling of the crankcase. The steel plate helps to reduce conrod-to-backplate friction which will increase the life of the conrod and improve engine efficiency and performance.
Sleeve: The 4 transfer port sleeve is the best option to provide high, but very linear, power through the entire RPM range and yet still keep the fuel consumption rate low.
Piston & Conrod: The R7 conrod is machined from a super light aluminum that is checked ultrasonically. The unique shape of the R7 rod creates less turbulence inside the engine.
The material of the piston is chosen for its excellent strength to weight properties. The flat shape of the top of the piston improves the efficiency of the engine. Each piston is coupled with the sleeve to get the best compression and longevity. This operation is done by hand, one by one, and checked by a precision measurement tool.
Turbo Plug Underhead Button: The combustion chamber has a special shape to increase performance during combustion. The sealing o-ring prevents vibration and also protects the assembled sleeve and crankcase from external dust. This head button is for turbo plugs, not standard plugs. It’s marked with an arrow to make sure you always assemble it correctly.
Bearings: Another improvement for 2015 is the use of a double sealed front bearing. This will help keep dust out of the engine and will make the engine easier to tune and allow it to better hold the tune.
The main bearing is calibrated and assembled by hand and its tolerance is twice checked by a precision measurement machine.
The combo includes:
Engine: M-4R .21 Tuned Competition Engine
3 venturis: 6.5mm, 7.0mm & 7.5mm
Exhaust System: Ultimate EFRA 2123 pipe plus manifold w/Masterfix system
Clutch - Ultimate Racing COMPAK clutch system with aluminium shoes and 1 mm springs (UR0620-XA)
Clutch Bell – Ultimate Racing 13T ventilated clutch bell with Ultimate Racing bearings
Air Filter- Ultimate Racing air filter case with pre-oiled foam