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O.S. Speed B21 Drake AD3 .21 Nitro Engine Combo
- $276.98
- Brands O.S. Speed
- Product Code: OSM1CJ01-1
- Availability: In Stock
O.S. Speed B21 Drake AD3 .21 1/8 Nitro Engine Combo with EBIS Break-InThe O.S. Speed B21 Drake AD3 .21 Nitro Engine Combo is a competition-oriented power system developed for 1/8-scale off-road racing. Created through the collaboration between O.S. Speed and Adam Drake, the AD3 builds on the previous B21 AD2 with updated internal components, revised airflow characteristics, and a lighter cooling h..
High Performance 1/8 Scale Nitro Engine Combo with EBIS Break In
O.S. Speed B21 Drake AD3 .21 1/8 Nitro Engine Combo with EBIS Break-In
The O.S. Speed B21 Drake AD3 .21 Nitro Engine Combo is a competition-oriented power system developed for 1/8-scale off-road racing. Created through the collaboration between O.S. Speed and Adam Drake, the AD3 builds on the previous B21 AD2 with updated internal components, revised airflow characteristics, and a lighter cooling head.
This combo pairs the B21 AD3 .21 engine with an O.S. Speed TB02/2090SC tuned pipe and 75 mm manifold, providing a ready-to-match exhaust setup for 1/8-scale racing. The engine is also supplied with EBIS (Engine Break-In Service), using The Drake Racing's specialized break-in process to prepare the engine before it is installed and tuned in the vehicle.
Key Features
Adam Drake Edition 3 competition .21 nitro engine
Designed for 1/8-scale buggy and truggy applications
3.49cc / .213 cu. in. displacement
Semi-long-stroke engine configuration
Adam Drake-specific cylinder design
Redesigned cylinder liner with optimized porting
Boost-bypass crankcase design
DLC-coated crankshaft with larger double tungsten counterweights
Lightweight, low-profile cooling head
21J carburetor
Includes 6.5 mm and 7.5 mm carburetor reducers
Steel front bearing and ceramic rear bearing
Includes TB02/2090SC tuned pipe
Includes 75 mm exhaust manifold
EBIS break-in service included
Suitable for competitive 1/8-scale off-road racing
Competition-Focused AD3 Engine
The AD3 was developed from the B21 AD2 platform with several changes aimed at improving drivability and power delivery. Its updated crankcase uses a boost-bypass design intended to improve throttle response and create a smoother transition through the RPM range.
The redesigned cylinder liner features optimized porting, while the semi-long-stroke configuration and larger tungsten crankshaft counterweights contribute to the engine's torque characteristics.
The result is a powerplant designed to deliver responsive low-end performance while maintaining strong output throughout the usable RPM range.
Lightweight Cooling Head
The signature AD3 cooling head is designed with a lower profile and reduced weight compared with the previous design. According to The Drake Racing, the AD3 head is approximately 14 g lighter and 3 mm lower, helping reduce weight and lower the engine's center of gravity.
A new inner O-ring also helps reduce vibration and improve resistance to dust entering the engine's combustion area.
DLC Crankshaft and Updated Backplate
The crankshaft uses a DLC coating and larger double tungsten counterweights. This construction is intended to provide smooth engine operation and support consistent power delivery.
The updated backplate incorporates a built-in thrust plate that reduces friction between the connecting rod and backplate. This design is intended to reduce wear and contribute to improved engine durability.
21J Carburetor with Two Reducers
The AD3 uses an O.S. 21J carburetor and comes with two blue-anodized aluminum carburetor reducers:
6.5 mm reducer — recommended for buggy applications
7.5 mm reducer — recommended for truggy applications
The interchangeable reducers allow the engine's airflow characteristics to be matched more closely to the vehicle and intended driving conditions.
TB02/2090SC Exhaust Combo
The AD3 Engine Combo is supplied with the TB02/2090SC tuned pipe and 75 mm manifold. The Drake Racing identifies this combination as its first-choice exhaust setup for the AD3 and recommends the 75 mm manifold particularly for buggy applications.
The shorter 75 mm manifold is intended to provide smoother power delivery with more emphasis on top-end performance. An 85 mm manifold is also available separately when a setup with more low-end power is preferred, particularly for truggy applications.
TB02/2090SC Pipe Specifications
| Specification | Details |
|---|---|
| Pipe Model | TB02/2090SC |
| Construction | Aluminum |
| Length | 167 mm / 6.6 in. |
| Diameter | 35.2 mm / 1.4 in. |
| Exhaust Outlet | 8 mm / 0.31 in. |
| Noise Rating | EFRA-2089 |
| Pressure Nipple | Pre-installed |
| Manifold Included | 75 mm |
| Intended Use | 1/8-scale off-road applications |
The TB02 pipe includes the manifold, pipe, springs, and header-to-muffler gasket.
EBIS Engine Break-In
This version includes EBIS (Engine Break-In Service) from The Drake Racing. Rather than using a conventional fuel-based break-in from a completely fresh engine, the EBIS process involves disassembling the engine and placing the piston, sleeve, and rod through a controlled hot-oil cycling process.
Measurements are taken before and after the process, followed by reassembly to factory specifications. The Drake Racing also sets O.S. Speed carburetors to Adam Drake's specifications as part of the service.
After the EBIS process, the engine still requires proper installation, heating, initial running, and final tuning. The Drake Racing recommends following its post-break-in procedure and making small adjustments based on fuel, vehicle, weather, and elevation.
Engine Specifications
| Specification | Details |
|---|---|
| Brand | O.S. Speed |
| Model | B21 Drake AD3 |
| Edition | Adam Drake Edition 3 |
| Engine Type | .21 competition nitro engine |
| Application | 1/8-scale off-road |
| Displacement | 3.49 cc / 0.213 cu. in. |
| Bore | 16.4 mm / 0.646 in. |
| Stroke | 16.55 mm / 0.652 in. |
| Configuration | Semi-long stroke |
| Maximum Output | 2.65 PS / 2.61 HP at 34,000 RPM |
| Practical RPM Range | 4,000–42,000 RPM |
| Carburetor | 21J |
| Front Bearing | Steel |
| Rear Bearing | Ceramic |
| Crankshaft | DLC-coated with double tungsten counterweights |
| Cooling Head | Lightweight, low-profile AD3 design |
| Engine Weight | Approx. 350 g / 12.35 oz |
| Break-In | EBIS included |
Engine specifications are from The Drake Racing's current AD3 information.
Complete Combo Includes
O.S. Speed B21 Drake AD3 .21 nitro engine
O.S. 21J carburetor
6.5 mm carburetor reducer
7.5 mm carburetor reducer
TB02/2090SC tuned pipe
75 mm exhaust manifold
Exhaust springs and related pipe hardware
Header-to-muffler gasket
EBIS engine break-in service
Recommended Applications
The O.S. Speed B21 Drake AD3 Combo is well suited for:
1/8-scale nitro buggy racing
1/8-scale truggy racing
Competition off-road RC vehicles
Racers looking for strong but controllable power
Drivers who want a matched engine-and-exhaust combination
Users who prefer an engine prepared with EBIS break-in service
Why Choose the B21 Drake AD3 Combo?
The O.S. Speed B21 Drake AD3 Combo brings the engine, tuned exhaust, and break-in service together as one competition-focused package. The AD3's revised crankcase, optimized cylinder, DLC crankshaft, lightweight cooling head, and 21J carburetor are designed around responsive and linear power delivery.
Adding the TB02/2090SC pipe and 75 mm manifold provides a factory-recommended exhaust combination, while EBIS break-in service saves the owner the initial engine-lapping process and provides a prepared starting point for vehicle installation and final track tuning.
For 1/8-scale racers who want a high-performance O.S. Speed engine with an appropriately matched exhaust system and professional break-in preparation, this AD3 combo offers a practical all-in-one setup.
