Exhaust Header recirculation

hi guys, was talking to this workshop boss who'd just done a turbo conversion on an Optra. No pics, sorry - but I've personally seen the car and taken a ride in it.

The exhaust manifold on the DOHC engine has a little extension on the right side of it (don't know if that's called cylinder 1 or 4)... see pic:

http://chevy.mrmax.dp.ua/graphic-poo...1/T3D11C65.png

and that little extension apparently recirculates exhaust gasses back into the engine to keep things cool.

Does anybody have any information on this, like is it just a groove lathed into it on the connecting side or any pics of the bit?

And how would that D16 header from the Civic fit into the scheme of things?

Thanks!!

with the d16 header, you have to weld a metal plate to block it off on the end of the header...theres a few other things you have to modify but its easier than starting from scratch....i dont know how circulating hot exhaust gasses keeps things cool lol i beleive it is their for emissions purposes

got pix?

EGR recirculates exhaust gasses back into the intake for combustion. Since exhaust gasses have no oxygen content, it won't burn. Also causes the mixture to run rich.

Small explosion vs big explosion = things cool off.

That's EGR though.. I have no idea what this recirculation bit on the header does...

thats what the recirculation is, EGR. idont have any pics because i didnt do it yet.

ok matey, looking forward to anybody with some pix of the stock header...

Yeah that's EGR. Back in around 2002, Caterpillar started using that system to meet tight emission laws. Everyone was screaming "OMG What will happen to the power and mileage?" Of course, both took a pretty severe hit....

EGR cools combustion temp. It's mainly there for emissions... it can also help prevent knock, but from what I've read, it's supposed to help fuel economy too. dunno...

It prevents NOx from forming during combustion. You can control knock with it, but yout ake a hit in power by doing it.


The extra channel is indeed the EGR. It links back through the head to the intake manifold.

You can block it off without too much problem. You may get a CEL, but I doubt it.

Probly not a good idea to block it, its there for a reason, think we could gain some power by blocking it?

you will have more power by blocking it. If you live in an emissions state, though... you will need to unblock it for inspection.