Given the American belief in making bigger better fighters: more range, more firepower, more armor, etc., I wonder why we never made a 4-engine fighter. Maybe they could have shortened up a B-29, clipped the wings some, gave it full strength maneuvering flaps, WEP for the engines, and more 20mms in the nose than you can imagine...
In the end we ended up with fighters in the size and weight class of the B-17: the F-14 and F-15. Both of which can carry more ordnance than the Queen of the Skies.