O.S. Speed B21 ‘Adam Drake’ AD4 .21 Offroad Engine

O.S. Engines has announced their latest engine collaboration with 1:8 Offroad legend Adam Drake, O.S. Speed B21 Adam Drake 4.   The .21 1:8 Offroad engines features a number of redesigned parts specific to Drake’s spec for better balance, more torque and more power for better driving performance.   The AD4 gets a newly designed cylinder liner uses 3 port design which changes the exhaust dimension for more torque.  They have also changed the crankshaft’s inner diameter for better response in low to middle range.  A new outer head has double anodised black and blue with new laser design and at same time lighter and better balance compared to the previous model.  The inner head’s combustion chamber has been redesigned for improved combustion efficiency, resulting in more torque.  The AD4 comes with φ6II and φ8 blue anodised venturis.

B21 AD4 Specs
Displacement： 3.49 cc / 0.213cu.in.
Bore: 16.4mm / 0.646 in.
Stroke: 16.55mm / 0.652 in.
Output :2.65 ps / 2.61 hp / 34,000 r.p.m.
Practical RPM range: 4,000-42,000 r.p.m.
Engine Weight:352g / 12.42 oz.

Standard accessories included
O.S. SPEED P3 glow plug
Reducer　6II (blue) AL2・Reducer　8mm (blue) AL
Exhaust seal ring
Dust cap set 3mm/16mm/18mm

Source: O.S. Speed [osspeed.com]