Here is a kit that comes with everything you need to learn about car engines. The Teching Mini Inline 4-Cylinder Car Engine Kit (DM13-L4-T) has over 360 parts. It runs on a 500mAh battery for around 30 minutes. It can be assembled in about 4 hours.
This engine measures 15.85 x 11.7 x 18.2cm. It has an aluminum alloy and stainless steel construction.