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O.S. Speed 21XZ-GT On-Road Engine (Turbo Plug)

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Low Price: $499.99
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The Speed 21XZ-GT On-Road Engine boasts many of the advances that Speed engines are famous for, and O.S. has developed the perfect power plant for dominating the 1/8 scale GT Touring class. With special modifications that make it ideal for on-road applications the 21XZ-GT delivers the performance GT Touring drivers demand, making it the obvious choice for this increasingly popular class.


  • Long stroke engine provides more torque
  • Five scavenger ports and three exhaust ports improve power in the mid- to high range
  • The crankshaft has been engineered for GT touring, and is silicon-potted and DLC coated with tungsten weights pressed in
  • The outer head features a lower CG and shiny fins
  • The dual adjustable carb is ROAR-legal, and comes with a 7 mm restrictor
Displacement: 0.213 cu in (3.49 cc)
Bore: 0.641 in (16.27 mm)
Stroke: 0.661 in (16.80 mm)
Practical rpm: 4,000-42,000
Power Output: 2.61 hp/2.65 ps @ 34,000 rpm
Weight: 12.45 oz (353 g)
Includes: Turbo P-3 plug

This product was added to our catalog on October 7, 2016

Average Rating: 5
Thursday, Aug 23 2018 (7 months ago)
O.S. Speed 21XZ-GT On-Road Engine
Essentially a Spec III buggy engine with more internal timing, this engine is a screamer. Ideal for GT racing, gets solid fuel mileage, essy to tune, pulls everyone down the straightaway. Running mine with a 2060 pipe and header. DLC crank will last several rebuilds no problem. The best costs some money, but it's worth it.