Chevrolet small-block engine
In 1992, GM created a new-generation small-block engine called the "LT1 350", not to be confused with the high-output Generation I LT-1 of the 1970s. It displaced , and was a 2-valve pushrod design. The LT1 used a reverse-flow cooling system which cooled the cylinder heads first, maintaining lower combustion chamber temperatures and allowing the engine to run at a higher compression than its immediate predecessors.
Lean-burn
All diesel engines can be considered to be lean-burning with respect to the total volume, however the fuel and air is not well mixed before the combustion. Most of the combustion occurs in rich zones around small droplets of fuel. Locally rich combustion is a source of particulate matter (PM) emissions.