The 2J was an open-cockpit race car built in 1970 by Chaparral which had a unique feature: it had two engines and only one of them powered the vehicle. The other engine was there just to suck air out of the bottom, which gave it the driving feel of a vehicle with much more downforce, but with the added benefit of it occuring even at low speeds.
The 2J only competed in the 1970 SCCA Can-Am racing series. The 2J wasn't able to compete for long, due to most forms of racing banning the design or engines used for anything other than powering the vehicle, like the SCCA did.