[roflwaffle]

While I do like to see tests done and data had, I'm a brat when it comes down to actually doing it...

A mathematician, an engineer and a chemist are at a conference. They are staying in adjoining rooms. One evening they are downstairs in the bar. The mathematician goes to bed first. The chemist goes next, followed a minute or two later by the engineer. The chemist notices that in the corridor outside their rooms a rubbish bin is ablaze. There is a bucket of water nearby. The chemist starts concocting a means of generating carbon dioxide in order to create a makeshift extinguisher but before he can do so the engineer arrives, dumps the water on the fire and puts it out. The next morning the chemist and engineer tell the mathematician about the fire. He admits he saw it. They ask him why he didn't put it out. He replies contemptuously "there was a fire and a bucket of water: a solution obviously existed."

Here's A nice thread on the subject.

Originally Posted by cleverlever

Patent 3,714,932 has some great information on the virtues of internal EGR derived from VVT and external EGR.
In a nutshell Internal EGR is vastly superior to external EGR in accelerating engine warm up. Internal EGR is superior to external EGR in reducing hydrocarbon emissions because the hydrocarbon emissions are more concentrated in the last part of the exhaust stroke. Internal EGR is better for uniform distribution of EGR because its regulation is confined to each cylinder rather than diffused in the intake manifold

I don't think newer engines would see much if any benefit but older ones w/o any EGR present may see a measurable benefit. That being said, would making some sort of exhaust throttle be worthwhile compared to just running a block heater at home, or even a block heater off an extra deep cycle battery/inverter away from home?