Tuning For Detonation

EGR introduces an inert gas into the combustion chamber so the combustion process is no as hot, the inert gas sort of sucks the heat out of the charge and reduces cylinder pressure. It actually increased efficiency somehow. It also reduces NOx but the reduction in cylinder pressure and heat is the knock (pre-ignition) reducer. Many people toss it but it really has no effect on performance, just looks a little busy on the sparse hot rod motor.