The Pratt & Whitney J58 was a jet engine that powered the Lockheed A-12, and subsequently the YF-12 and the SR-71 aircraft. The J58 was a single-spool turbojet with an afterburner. It had a unique bleed from the compressor to the afterburner which gave increased thrust at high speeds. This feature caused it to be referred to as a turboramjet in some writings. It delivered 25,000 pound-force of thrust without afterburner (dry) and 34,000 with afterburner (wet).