#OS1EK01 - O.S.SPEED B2105 3.5cc Buggy Engine Combo Set
Key Specs
About this product
O.S.SPEED 1EK01 – B2105 3.5cc Buggy Racing Engine Combo Set
The top of the world again!
O.S.SPEED B2105 was born after further evolution.
O.S.SPEED’s off-road racing engine has undergone further evolution. The B2105, which has evolved into the fifth generation of the B21 series, is designed to secure power to gain an advantage in harsh off-road racing scenes and pursue a driving feel in any situation. change. This allows for smooth rotation. Furthermore, the effect of a lighter outer head also overlaps, and we have succeeded in improving drivability.
The newly designed cylinder/piston uses 3 ports. The port shape has been changed and the air-fuel mixture flow has been reviewed to achieve more useful torque performance.
The newly designed crankshaft has undergone O.S.SPEED’s traditional DLC processing and the internal shape has been revised to improve not only power characteristics but also rotational hold.
The outer head uses a new design. Succeeded in improving drivability in any situation by reducing weight.
The crankcase has inherited the well-established B2104.
The cover plate adopted from B2104 uses a specially treated thrust plate to reduce wear caused by interference between the rotating connecting rod and the cover plate, extending engine life.
This combo set includes a TB02 EFRA2089 pipe + MB01-75 manifold set to maximize the B2105 engine performance. It’s also available without the exhaust system (OS1EK00).
Specs:
Displacement: 3.49cc
Bore: 16.27mm
Stroke: 16.80mm
Power: 2.68ps / 2.64hp @ 34.000RPM
RPM range: 4000-42.000
Weight:348g
Standard accessories:
Glow plug: T-P3
Venturi: 6mm & 6.5mm
Exhaust seal ring
Dust cap set: 3, 16 & 18mm
TB02 EFRA2089 pipe + MB01-75 manifold set
Frequently Asked Questions
This is a 3.5cc nitro engine designed for competitive off-road racing, so it's suited to experienced RC enthusiasts rather than beginners. You'll need familiarity with nitro engine tuning, maintenance, and operation before purchasing.
The combo set includes the B2105 engine, TB02 EFRA2089 exhaust pipe, MB01-75 manifold, a T-P3 glow plug, two venturis (6mm and 6.5mm), an exhaust seal ring, and three dust caps (3mm, 16mm, and 18mm).
This is a nitro engine, so it runs on nitro fuel rather than electricity and does not require battery charging. You'll need to source appropriate nitro fuel separately and maintain the engine according to O.S. specifications.
The engine produces 2.68ps (approximately 2.64hp) at 34,000 RPM, with an effective RPM range of 4,000–42,000 RPM, delivering evolved power and torque for competitive off-road racing.
This 3.5cc engine is a standard displacement for 1/8 scale nitro buggies and is compatible with buggies designed for EFRA2089 exhaust systems. Check your specific buggy manual or manufacturer specs to confirm compatibility.

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