The cylinder and sleeve design has been developed starting from the classic Japanese 3-port architecture, well known for its simplicity, reliability, and strong torque characteristics. Reds Racing engineers further refined this concept by introducing additional internal flow channels designed to guide and optimize the air-fuel mixture movement inside the cylinder.
The cylinder is paired with an ultra-lightweight piston, specifically designed to reduce reciprocating mass. By minimizing the moving masses inside the engine, Reds Racing engineers were able to further improve engine responsiveness and maximize overall power output.
Each combustion chamber has been specifically designed to perfectly match the characteristics of its respective fuel blend, ensuring the best balance of performance, reliability, and fuel efficiency under a wide range of racing conditions.
In addition, the AirBoost backplate is coated with a DLC (Diamond-Like Carbon) treatment, which reduces sliding friction between the connecting rod and the backplate. This advanced coating improves engine efficiency, reduces wear, and contributes to lower fuel consumption.
Easy to Tune, Built to Win – 21J with Venturi XFlow™
To guarantee extremely easy tuning and consistent performance on every track, the 321 ESTREMO features a carburetor based on the legendary O.S. Speed 21J, one of the most reliable and widely used carburetors in the RC racing world.
REDS Racing engineers selected the proven 21J platform and further enhanced it with the Venturi XFlow™ system, designed to maximize airflow and improve carburetion stability.
Thanks to its Ultra Short design, the Venturi XFlow™ optimizes the air intake path and allows the engine to breathe more efficiently. This results in faster throttle response, easier carburetor tuning, and stronger overall engine performance.
The Venturi XFlow™ is available in three sizes to adapt the engine to different track conditions and racing preferences:
- 6 mm – Maximum torque and improved fuel efficiency
- 7 mm – Perfect balance between power and drivability
- 8 mm – Maximum airflow and top-end performance
This system ensures stable carburetion and precise throttle response, giving drivers the confidence needed to push the engine to its limits in any racing condition.
REDS Ultra-Lightweight Cooling Head
The REDS ultra-lightweight cooling head has been engineered to maximize heat dissipation while minimizing overall engine weight.
Its optimized fin structure improves cooling efficiency and helps maintain stable engine temperatures even during demanding racing conditions, ensuring consistent performance during long finals and intense competition.
Extreme Durability and Precision Engineering
The new engine integrates several advanced durability improvements designed to maximize performance and reliability.
Both the crankshaft and the backplate feature DLC (Diamond-Like Carbon) coating, a technology known for its exceptional hardness and extremely low friction coefficient.
Thanks to this advanced treatment, the crankshaft durability can increase by up to three times compared to a conventional steel crankshaft, while also reducing internal engine friction.
The reduced friction between the connecting rod and backplate also helps extend conrod life by approximately 50%, improving long-term reliability during demanding racing conditions.
The crankshaft features a double-balanced design, while its internal geometry has been revised to improve both power characteristics and engine smoothness.
The engine crankcase has been manufactured according to the highest quality standards, ensuring excellent rigidity, perfect component alignment, and maximum durability.
Key Technical Features
- 3-port engine design focused on high torque output
- Advanced cylinder and sleeve design with optimized internal flow channels
- Ultra-lightweight piston to reduce reciprocating mass
- REDS ultra-lightweight high-efficiency cooling head
- AirBoost DLC-coated backplate for improved power and efficiency
- DLC-coated crankshaft with double balancing
- Carburetor based on O.S. Speed 21J design
- Venturi XFlow™ intake system available in 6, 7, and 8 mm sizes
- Two dedicated combustion chambers for 16% and 25–30% nitro fuels
Two Engines, Two Racing Philosophies
With the introduction of the 321 ESTREMO, Reds Racing now offers two distinct engine platforms designed to suit different track conditions and driving styles.
- 7-port engine architecture
- Exceptional top-end speed
- Outstanding fuel efficiency
- Extremely smooth and linear power delivery
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Ideal for high-speed tracks and European-style layouts
- 3-port engine architecture
- Strong bottom-end torque and acceleration
- Excellent throttle response and drivability
- Designed for technical tracks with big jumps
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Ideal for American-style layouts and demanding off-road conditions
Together, the 721 Superveloce and the 321 ESTREMO give racers the possibility to choose the engine that best matches their track conditions, driving style, and racing strategy.
With the introduction of the X Line, Reds Racing expands its presence in the off-road racing segment, offering drivers a new engine platform designed to deliver a different performance philosophy alongside the established 721 S Line.
The 321 ESTREMO represents the perfect fusion of Italian racing engineering and Japanese manufacturing precision, setting a new benchmark for performance, drivability, and reliability in the world of off-road RC racing engines.
Technical Specifications
- Category: 1/8 Buggy and Truggy
- Inlet Ports: 3- Outlet Ports: 1
- Front Bearing: 7×19×6 with single high-performance seal
- Rear Bearing: 14×25.4×6 – 9 balls high-durability ceramic bearing
- Carburetor Type: VLX3-A aluminum long needle
- Venturi Diameter: 7.0 mm (optional venturi sizes: 6.0 mm and 8.0 mm – carburetor body 9.0 mm)
- Backplate: AirBoost DLC-coated backplate
- Crankshaft: DLC-coated with two tungsten balancing weights
Recommended Accessories
To maximize the performance of your 321 Estremo™ engine, Reds Racing recommends pairing it with the following components:
- Glow Plug: REDS TS3 or TS4
- Exhaust System: 2143 X-ONE X Line
- Clutch System: REDS TETRA-X Clutch System
- Fuel: 16–30% nitro with 8–10% oil
Not compatible with S Line Exhausts, manifolds, gaskets, piston/sleeve/conrod set and spring set.