That's a good request. I've seen some great photo sets in the Library of Congress archives. I'll see what I can dig up.
These photos are pretty outstanding as well. Sourse NASA Altitude Wind Tunnel & Space Power Chamber Galleries archives.
Boeing B-29
Boeing XB-29-BO (SN 41-002, the first XB-29 built). (U.S. Air Force photo)
B-29 arrives in Cleveland as part of the Aircraft Engine Research Lab's intensive study of its Wright R-3350 engines
B-29 arrives in Cleveland as part of the Aircraft Engine Research Lab's intensive study of its Wright R-3350 engines
AUXILIARY COOLING DUCTS ON B-29
AUXILIARY COOLING DUCTS ON B-29
B-29's Wright R-3350 Engine Nacelle in Altitude Wind Tunnel Shop
B-29's Wright R-3350 Engine Nacelle in Altitude Wind Tunnel Shop
B-29's Wright R-3350 Engine Nacelle in Altitude Wind Tunnel Shop
Cowl for B-29's Wright R-3350 Engine in Altitude Wind Tunnel Shop
Front View of Wright R-3350 Engine
Wright R-3350 Engine for B-29 in Altitude Wind Tunnel
Wright R-3350 Engine for B-29 in Altitude Wind Tunnel
Wright R-3350 Engine for B-29 in Altitude Wind Tunnel
Wright R-3350 Engine for B-29 in Altitude Wind Tunnel
Fuel Injection Manifold on Wright R-3350 in Altitude Wind Tunnel
Front View of Wright R-3350 Engine