Originally Posted by
MaxPower
The main reason for making an EGR is to allow an inert gas to go into your combustion chamber. By taking up space when mixing with your a/f it lowers combustion temps and saves gas by giving a cooler burn and more controlled flame front with less fuel used. It is only used on half throttle applications, Not WOT. I dont see how it would take away any useful HP. By taking it off or blocking it there will be no lean mixture since your car will compensate to remain stoichiometric. I have yet to see plausible results on a car gaining HP on a dyno but I have seen a lot of Nox reduction from the lower combustion temps.
Also I dont even think the EGR is used until your are in closed loop.
EGR is a system. Not all of them have valves. Many of the older V8 style systems are continuous. Some manufacturers use a closed-loop only setup. Want a good example of a WOT open setup? 1st gen Dodge Neon. Pretty good horsepower gains reported from EGR block-off.
I understand it reduces emissions outputs. But it does so by pre-heating the combustion charge. This makes for less dense air, less oxygen in the air, and less fuel needed to create a complete burn. It effectively leans out the system, and allows it to function well. By removing this charge, it's entirely possible it will set a code, but aside from that, it will cause there to be an additional amount of oxygen, and therby the car can run lean.