Captioned as found.

A close-up of the 410 H.P. Wasp,
the first engine used in the first airmail plane.
Location: US
Date taken: 1943
Photographer: Ralph Morse
http://www.gstatic.com/hostedimg/70046990bcfbb618_large

A close-up of the R-985 9 cylinder 450 H.P. Wasp Jr
http://www.gstatic.com/hostedimg/00ffe273052b8c0f_large

A close-up of the R-1340 9 cylinder 600 H.P. Wasp engine.
http://www.gstatic.com/hostedimg/70e086049c975d03_large

A close-up of the R-1830 14 cylinder 1200 H.P. Twin Wasp engine.
http://www.gstatic.com/hostedimg/844d7762e663416b_large

A close-up of the R-2800 18 cylinder 2000 H.P. Double Wasp engine.
http://www.gstatic.com/hostedimg/e0678fb7da6f25e1_large
http://www.gstatic.com/hostedimg/94123d79abeecf94_large

Man working on power section of 'Wasp' airplane engine at
Pratt & Whitney aircraft parts factory.
Location: Hartford, CT, US
Date taken: 1941
Photographer: Dmitri Kessel
http://www.gstatic.com/hostedimg/8aa5c494803611ab_large
http://www.gstatic.com/hostedimg/6602b24a7498b3d1_large