As if the F-35s Pratt & Whitney F135 was not powerful enough, Pratt & Whitney has developed an engine core upgrade and won a $1.3 billion contract to continue the work to add more efficiency, electrical power, and other improvements to the 43,000 lbs (191 kN) with afterburner F135. Pratt & Whitneyan RTX firmaims to support all F-35s regardless of variant, with an upgraded, durable engine as Block 4 is rolled out.