If you just a cool poster to put on the wall, you might check stores that have aircraft pitcures or tradeshows/airshows where Allison Engines, GE Aircraft, and other manufactures show there hardware.  

If you need better detailed engineering-like drawings, those might come from an aircraft mechanics repair handbooks through certified FAA instructional schools.

Real engineering drawings from the manufacturer are next to impossible.  But if you work for one of those companies, I guess you might have the privelage of viewing those documents.  There could be hundreds of them.