It is popular for forklift to be equipped by diesel engine, because diesel engine has a better economical cost performance than gas engine. The difference between diesel engine and gas engine is that igniting is difference. For diesel engine the diesel is burned by compression air and gasoline is burned by spark.
The main mechanisms of the forklift diesel engine include: cylinder block, crank-link mechanism, gas distribution mechanism, fuel system, lubrication system, cooling system, and electrical system. http://www.leadingforkliftparts.com