EGR and performance questions

There is a side benefit to running EGR at part throttle. And that is the way it affects compression. With the inert exhaust in the cylinder the cylinder pressure can be artificially increased. Since the gas does not chemically react with the fresh gas, it's just occupying space. What does that mean?
Firstly, let's say you have teener with an Scr is 8/1. Well Scr means squat to a running engine so let's convert that to Dcr. With a 240* cam that works out to about 7.0/1 Dcr . That 7/1 means,it might at WOT, be squeezing just 560 cc, out of a theoretically possible 650cc, into a 93 cc space...
Well let's say you are tooling around at 2200 rpm, or some close rpm on the highway. Your throttle-blades will be nearly closed. Your engine will be ingesting a fraction of it's maximum capacity.
Let's say it might be ingesting only 30%, maybe less, so let's estimate .3 x 560 = 170cc. So you are only squeezing 170 cc under this cruise parameter, and your running Dcr is only 170/93 = 2.1/1!
What? you say? Well if you've never stopped to think about this, this is a hard pill to swallow, and no wonder the LC teener can be a slug when it comes to fuel mileage! You just have to wonder how the factory ever got fuel mileage out of them in the first place.
Okay, so the key to better fuel mileage is more compression, right? Every body knows that. But let's say some VIP nixes the hi-comp idea.What can you do?
Well lets put something into the combustion chamber to momentarily take up some space. That would do it, wouldn't it? Enter EGR. let's say you could put 30% EGR in that chamber under cruise conditions. That would be .3 x 170 = about 50cc. now you are compressing 170 + 50 into a 93 cc space. That calculates out to 2.37/1 Dcr
Big deal you say! That's only a quarter of a point.
And you'd be right, it is a big deal,cuz it's about 13% more than without. So how does that translate to fuel mileage? I have no idea. But considering as how a lightweight 69 Dart-without EGR got maybe 17 to 19 mpgUS, and a heavyweight 84 NewYorker-with EGR got 20ishUS lugging around some 1000 more pounds; I'd have to say EGR works.
Just hook up a scanner to any modern EFI vehicle and watch what the computer is doing with the EGR valve. They are dumping huge amounts of EGR into the mix, and Fuel economy is ever increasing......And this is just one effect of EGR.
Now this bs talk is overly simplified in all kinds of ways, but I think it's pretty easy to understand as presented.Keep in mind this works very well on LC engines. I don't think I'll be engineering it into my 10.7Scr, 360, anytime soon.As mentioned elsewhere, EGR is eliminated at WOT and at(usually) Idle. So power and idle quality remain unaffected.
All figures are estimates and conservative, and no small animals were hurt by the results.
Your results may vary