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2013 NHRA Pro Stock Motorcycle Engine Specifications
Thursday, November 15, 2012


2013 NHRA Pro Stock Motorcycle Engine Specifications

“NHRA spent countless hours speaking with the engine builders and manufacturers as well as the race teams to come up with the final engine specifications for 2013,” said Glen Gray, vice president of technical operations, NHRA. “As a result, we believe NHRA fans are in store for some exciting side-by-side racing in the Pro Stock Motorcycle category in 2013.”


  • V-twin design - up to 160 cid
  • In-Line 4 cylinder type – up to 107 cid


  • V-twin engine cylinder angle is 60 degrees. Maximum allowable cylinder angle from vertical is 45 degrees.


  • Maximum bore spacing is 98mm for In-Line. Maximum cylinder offset on V-twin is 1”.


  • All V-twin engines must use a push-rod, rocker arm design for the valve activation. Minimum push-rod length is 8.0”.
  • All in-line 4 cylinder engines must use the overhead camshaft design.


  • Maximum 2 valves per cylinder for all engines.
  • The only exception is the Kawasaki engine. The Kawasaki engine is allowed maximum of 4 valves per cylinder.
  • Variable cam timing devices, pneumatic actuation and finger followers are not permitted.


  • Fuel injection permitted.
  • Direct injection (into the combustion chamber) not permitted.
  • All ECU systems must be NHRA accepted.
  • Maximum one injector per cylinder.


  • All ignition systems must be NHRA accepted.
  • Aftermarket crank triggered, capacitive discharge (cd) ignition systems permitted.
  • Magnetos are not permitted.

About NHRA
Headquartered in Glendora, Calif., NHRA is the primary sanctioning body for the sport of drag racing in the United States. NHRA presents 23 national events featuring the NHRA Full Throttle Drag Racing Series, NHRA Lucas Oil Drag Racing Series and NHRA Pro Mod Drag Racing Series presented by ProCare Rx. NHRA provides competition opportunities for drivers of all levels in the NHRA Summit Racing Series and the NHRA Drags: Street Legal Style presented by AAA. NHRA also offers the Jr. Drag Racing League for youth ages 8 to 17. In addition, NHRA owns and operates five racing facilities: Atlanta Dragway in Georgia; Auto-Plus Raceway at Gainesville in Florida; National Trail Raceway in Ohio; Lucas Oil Raceway at Indianapolis; and Auto Club Raceway at Pomona in Southern California.

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