Exhaust Header recirculation

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03-04-2007, 06:05 AM

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!!
03-04-2007, 01:03 PM
AVE0SAM

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
03-04-2007, 01:20 PM

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...
03-04-2007, 01:24 PM
AVE0SAM

thats what the recirculation is, EGR. idont have any pics because i didnt do it yet.
03-04-2007, 04:27 PM

ok matey, looking forward to anybody with some pix of the stock header...
03-04-2007, 05:36 PM
ontarian_frog

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....
03-04-2007, 11:24 PM
mtlswift

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...
03-05-2007, 02:02 AM

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.
03-05-2007, 05:35 AM
Nemasys

Probly not a good idea to block it, its there for a reason, think we could gain some power by blocking it?
03-05-2007, 08:56 AM
exodus

you will have more power by blocking it. If you live in an emissions state, though... you will need to unblock it for inspection.
03-05-2007, 09:07 AM

ah-ha! found a pic of it in subachad's website:

http://www.uniquemotorsports.com/Dae...oo_header2.JPG

Does anybody know... this channel just lets exhaust into the head right? Does the exhaust in any way get into the combustion chambers except via the EGR valve?

That is.. if I left the header in place, but prevented EGR from getting back into the air intake perhaps by placing a small filter where the EGR valve is, would that make a difference?
03-05-2007, 09:07 AM

It's only open sometimes though, so it's not like you'll see massive gains...

Not worth the effort... it falls under the law of diminishing returns
03-05-2007, 11:09 AM

on this engine it has no effect, my egr tube has been broken for 4 onths. I just crimped the tube close at the break. guess what engine light came on . code says low flow in egr system. as of power. no power gain, or at least not noticeable. I've come to the conclusion that the only way your gonna make good power with this engine is to turbo it. Besides that it's just made to get from A to B.
03-05-2007, 01:11 PM
mtlswift

It vents to the intake manifold
04-08-2008, 03:42 AM
unknown_wonder

Re: Exhaust Header recirculation

so your saying that a d16 header will fit. But what if you dont cover the extenction on the right? will it make a difference
04-08-2008, 09:13 AM
g0ast

Re: Exhaust Header recirculation

This talk of blocking it is just bad, I don't need to do research on it, figure out exactly what that channel does or anything like that to know it wasn't put there for no reason, I understand auto manufacturers doing stuff like that to make it more efficient, safer, quieter, ect...

But I really wouldn't wanna try altering something in the engine until I know what it does, what would change if I did it and the advantage of it and the health of the engine in the long run.

I pretty much go by a customization policy of being able to change anything on or in the car, but the one "off-limits" area is the engine, until I'm guaranteed that whatever I change won't make me regret it later (you can get a new bumper if the one you put in breaks, but good luck with a new engine).

Anyway, don't take a risk, stay with the proven sciences (turbo/super/nitro ect).
04-08-2008, 11:26 AM
deniswhite1

Re: Exhaust Header recirculation

Quote:

Originally Posted by maded

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!!

more info on the turbo optra, and pics?
04-08-2008, 06:05 PM
ontarian_frog

Re: Exhaust Header recirculation

Most of you guys are right about EGR...let's all take you guys' answers and make one good one.

EGR or Exhaust Gas Recirculation has been around for a long time in passenger cars. Longer than in Caterpillar engines code C-XX. EGR lowers combustion temperatures, which in turns lowers the output of NOx and makes a car legal to drive in emission states and provinces. The way combustion temperatures are lowered is simple: There is less room for oxygen in the combustion chamber when exhaust gases are present, therefore less oxygen = lower temperature. Anybody who handles an Oxy-Acetylene torch should know this. Too much oxygen, you get detonation.

As some of you pointed out, EGR is not always letting exhaust gases into the intake manifold all the time. There is a solenoid and a sensor which controls this. What EGR allows manufacturers to do is to advance timing and run higher compression engines without the need for a higher octane gasoline. That equals to better efficiency (more mpg) and savings passed onto car owners (less trips to the pump).

Why EGR is bad for for power. Well this one can finally be put down as mostly a myth. The myth comes from the first engines, without a good management unit and EGR being on all the time. Newer engine make use of EGR to actually turn it into an advantage. The L91 engine (1.6L Aveo engine) wouldn't be able to run 87 octane gas efficiently without it that's for sure.

Although this is for Australia, here is a good read none the less about EGR (from way back when) http://autospeed.com/cms/A_2677/article.html
04-08-2008, 06:17 PM
AVE0SAM

Re: Exhaust Header recirculation

Quote:

Originally Posted by deniswhite1

Quote:

Originally Posted by maded

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!!

more info on the turbo optra, and pics?
04-08-2008, 06:26 PM
xtreme 2

Re:

Quote:

Originally Posted by Brian5475E

on this engine it has no effect, my egr tube has been broken for 4 onths. I just crimped the tube close at the break. guess what engine light came on . code says low flow in egr system. as of power. no power gain, or at least not noticeable. I've come to the conclusion that the only way your gonna make good power with this engine is to turbo it. Besides that it's just made to get from A to B.

If you just crimped it closed you are going to have a large exhaust leak... not to mention and Intake Vacuum leak...