Competitors come and go -- but champions keep on winning. For rock-solid dependability and title-taking performance, there's only one choice for the long run: O.S.

• Designed for top-level racing and head-to-head competition with premium-priced engines.
  
  
• Available in 3-port models for ROAR-legal racing — and a 5-port powerhouse for .12 open classes!
  
  
• Virtually perfect bore-to-stroke "square" creates the broadest possible power band and the ability to harness it for bottom-end torque, top-end speed or any combination of the two.
  
  
• Factory-milled and flared crankcase, crankshaft and ports smooth the flow of fuel, air and exhaust gasses, reducing power lost to turbulence and boosting performance.
  
  
• "Teardrop" ribs inside the crankcase channel and compress fuel-air flow for added power and better burn.
  
  
• CNC-machined A7075 aluminum piston and knife-edge conrod reduce rotational mass, improving efficiency and available power.
  
  
• Hefty, 12 mm crankshaft is CNC-machined for tighter tolerances and minimum vibration — enlarged transfer port on 5-port 12TZ (OSMG1998) increases fuel-air volume and horsepower!
  
  
• Also included: true ABC construction; enlarged rear and rubber-sealed front bearings; oversized, 1.92 in. (49 mm) 2-piece turbo head and P6 Turbo Plug.
  
  

Created specifically for 12TZ engines, these one-piece pipes are all-metal and available for both right- and left-exhaust vehicles.

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Stock Number	Description	Carb	Shaft	Displacement (cu in)	Bore (in)	Stroke (in)	Weight (oz)	Power Output (HP @ rpm)	Parts Listing
OSMG1997	12TZ(P)-T 3-Port	3-needle 11H slide-valve carb	Pilot	0.128 (2.1 cc)	0.543 (13.8 mm)	0.551 (14 mm)	7.9 (225 g)	1.5 @ 33,500	11373
OSMG1998	12TZ(P)-T 5-Port	3-needle 11H slide-valve carb	Pilot	0.128 (2.1 cc)	0.543 (13.8 mm)	0.551 (14 mm)	7.9 (225 g)	1.62 @ 34,400	11375
OSMG2019	12TZ(P)-T3	3-needle 11M rotary carb	Pilot	0.128 (2.1 cc)	0.551 (14 mm)	0.551 (14 mm)	7.9 (225 g)	1.5 @ 33,500	11372

Turbo Plugs
Displacement: 0.128 cu in (2.1 cc) • Bore: 0.543 in (13.8 mm) • Stroke: 0.551 in (14 mm) • Practical RPM Range: 5,000-40,000 • Weight: 7.9 oz (225 g) • Include: P6 turbo plug, 5.5 mm carb restrictor (T5 also includes 6.5 mm restrictor). Require: manifold, tuned pipe, air cleaner		OSMG2695 P7 Medium		OSMG2696 P6 Hot		OSMG2698 P8 Cold		OSMG2699 P3 Hot