X12 Engine

X12 (2021) for Motorhome & RV

Power 350 - 500 hp
261 - 373 kW
Torque 1250 - 1700 lb-ft
1695 - 2305 N•m
Certification EPA 2021

Select an Application

Available Regions

US and Canada,  Russia,  Africa & Middle East,  Mexico,  Philippines,  Singapore,  Brazil,  Bolivia,  Uruguay,  Paraguay,  Argentina,  Colombia,  Central America,  Europe,  Korea,  Japan


For the 2021 X12 we’ve updated our engine with a focus on improved reliability, lower maintenance cost, better performance, while meeting more stringent EPA Greenhouse Gas standards. The good news for Motorhome & RV customers is that lower Greenhouse Gas emissions means improved fuel economy. We’ve been able to do this by optimizing our existing technology, rather than introducing new emissions equipment. 

For 2021, the X12 maintains the 600 lb. weight savings compared to other engines in this class and produces up to 500 hp and 1,700 lb./ft of torque. A new optional air compressor resonator gives customers the option to reduce engine noise both inside and outside the vehicle. The X12 also features extended maintenance intervals for oil and filter up to 18 months and fuel economy improvements of 2.5%.

X12 Specifications



Inline 6 


720 CU IN       11.9 L 

Lube Oil Capacity 

42 QT              39.8 L 

Biodiesel compatibility 

            Up to B20 

Engine Braking Horsepower 

Up to 450 HP @ 2300 RPM 

Idle Speed 

          600 - 800 RPM 

Governed Speed 

              2000 RPM 

Engine Weight (Dry) 

 250 LB            930 KG 

Aftertreatment Weight** 

173 - 191 LB       78-87 KG 




Engine Model  Max. Power HP (kW)  Peak Torque lb-ft (Nm) @ RPM  Governed Speed (RPM) 
X12 500  500 (373)  1700 (2305) @ 1000  2000 
X12 455  455 (339)   1700 (2305) @ 1000  2000 



  • Cummins on Every Corner – Over 3,700 authorized locations across North America to support parts and service needs. 
  • Peace of Mind — Base warranty backed by Cummins for a full 5 years/100,000 miles, whichever comes first. 
  • Cummins Guidanz™ — This app allows you to read check engine lights and share via email with your service provider. 
  • Longer Optional Extended Coverage — Unmatched full-engine coverage options of up to eight years are available, for peace of mind and predictable maintenance costs.

X12 2021 RV Maintenance Intervals


Oil and Filter 18 months/1500 hours/40,000 miles  
Fuel Filter   12 months/1500 hours/40,000 miles  
Valve Lash Check    6750 hours/300,000 miles  
Crankcase Breather Filter   Maintenance Free 


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