This is a Short Crankshaft Version of the Traxxas TRX-15 Pro Engine. It is for modelers who want higher performance than a .12 size engine in their 1/10 scale kits such as Nitro Stampede, RC-10GT or GTX. This is a Non-Pull Start Version. FEATURES: ABC (Aluminum Brass Chrome) Construction Oversized Machined Aluminum Blue/Silver Anodized Cylinder Head Channelled Beam Connecting Rod for Improved Oil Flow Precision Ball Bearings Large-Bore, High-Flow Carburetor Double O-ring Seals on High and Low Needles Industry-Standard Mounts and Crankshaft Lengths to Fit Most Applications. INCLUDES: One Assembled Engine Without Pull Starter One Air Cleaner (black rubber with black foam element) One Full Instruction Book and Parts Exploded View One "Traxxas" Decal Sheet Installed Glow Plug (standard long--no idle bar) SPECS: According to Traxxas, this engine will produce 20% more power than the TRX-12. Which is approximately 9-11% more power than the O.S. CZ-Z. These figures are tested on a dyno (loaded) which provides power curves on a computer. Traxxas was not able to provide any numbers on BHP, bore, stroke etc. Keep in mind that these figures are often useless, as they will vary from engine to engine. And there are other variables to consider: the kit, terrain, %nitro in fuel, etc...... Overall Length (front end of shaft to back of engine): 83mm (3.25") Height (top of cylinder head to bottom of backplate): 93mm (3-5/8") Width (cylinder head): 41mm (1-1/2") Mount holes (center to center): left to right: 31mm (1-1/4") front to back: 11mm (7/16") Overall width of mounting ears (where the holes are): 40mm (1-9/16") ***Mounts the same as an OS .12 and .15 CV*** REQUIRES: A 1/10 scale kit to put it into and 5%-20% Glow Fuel. COMMENTS: For the Pro 15 w/Short Crankshaft & Pull Start, use TRAG4007. If you have any other kit, I would call the manufacturer thereof- or call Traxxas directly at 1-888-TRAXXAS. Traxxas engines run much hotter than "normal" engines (O.S., ASP, Thundertigre, etc.) Therefore, Traxxas recommends their Top Fuel (TRAP5010) and their glow plug (TRAG3230) to run the engine cooler. JAL 2/5/99 ir/jl