try to build the "Customs JRL Cycles' Radial Chopper", its a chopper with a radial engine, under the tank fuel, AWESOME!!!
ps: if you want to build it use the first engine (on top & left)on your first picture.
I didn't think it was possible to create so realistic radial engine models in Lego in this small scale. Have you only used existing lego-parts or did you have to modify any piece. It would be nice to see the construction in some more detail. Once more an excellent work!!