This is the Ultimate .21 off-road Ultimate M-4R Tuned Engine.
The M-4R is a 4 port engine with tuned crankshaft and represents the most powerful and speedy 1/8 off-road engine of the Ultimate Engines line, with great and linear power at both low and high R.P.M. It boasts the most advanced technology and a top level human capital that team up to further improve fuel mileage, overall performance and reliability.
The M-4R has all what an engine needs to compete against other market leading engines, but at an affordable and very competitive price for a top quality race engine.
It stands out the exclusive oversized cooling head 100% designed by Modelix R&D department also used on the M-5 and M-8 engines to keep the engine cooler and improve performance at high temperatures. It’s been drilled and milled out to make it lighter and keep the overall center of gravity of the engine low. Besides this, the diameter of the central hole of the head where the glow plug fits has been reduced to better measure the temperature for those who use a temp gun .The reason to do this is to avoid that the temp gun touches the glow plug when measuring the temperature and have a more accurate temp reading.
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.
The exclusive 13mm turbo crankshaft has also been designed by the team and hand tuned and lightened to reduce rotation weight and is surprisingly strong and reliable thanks to our special steel and heat treatment.
The shape of the rear cover helps to optimize the crankcase filling and reduces dead space. The steel plate helps to reduce conrod-backplate friction and increases the life of the conrod and improves engine efficiency and performance.
This 4 transfer ports sleeve is the best option to provide high linear power at each RPM and low fuel consumption.
PISTON & CONROD
The R7 conrod is machined from a super light aluminum that has been checked ultrasonically. The unique shape of the R7 rod creates less turbulence inside the engine.
The material of the piston has been 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 made by hand, one by one and checked by a specific precise measurement tool.
TURBO PLUG UNDERHEAD BUTTON
The combustion chamber has a special shape to increase the performance during combustion. The sealing o-ring avoids vibrations and also protects the assembled sleeve/crankase from external dust. This head button is for Turbo plugs, not Standard plugs. It’s been market with an arrow to make sure you always assemble it correctly.
The front bearing has a double rubber shield protection against dust. The main bearing is calibrated and assembled by hand and its tolerance is twice checked by a specific measurement machine.
We recommend using the new Ultimate EFRA 2123 Off-Road Super Strong Pipe Set with Manifold. This high quality aluminium pipe has been developed for competition racing, to provide great throttle control, increase power and high top speeds. With its hard chrome-plated finish, this pipe features precise throttle response in the lower rpm range, combined with smooth and linear performance up to the high rpm range to produce great power characteristics and efficient fuel consumption. The Ultimate EFRA 2123 is a great choice for all current 1/8 off-road engines, and has been IFMAR, EFRA, ROAR, DMC and BRCA approved (EFRA# 2123).