What does egr/air do?
02-26-2008, 04:24 PM
#21
EGR may be for emissions primarily, but it DOES have a benefit in regular driving.
First is lower combustion chamber temps. This is TRUE. What happens is that during part throttle (which is what MOST of our cars spend it's life in) is that it recirculates combustion chamber gases back into the intake stream. Combustion chamber gases have bits of unburnt fuel but the majority of it cannot be reburnt. This has the effect of altering the air fuel mixture in such a way that the combustion reaction is slowed and the combustion temperature reduced. It's significant enough that NOx particles cannot be created.
For example typical NOx production occurs at a combustion temperature in the 1500F range. EGR can reduce it a few hundred degrees to deter this from occuring.
Now something else can be done as well. For extended crusing, the timing can be advanced significantly. The effect is that more timing and less fuel can be used. The end effect is worth as much as 2-4 mpg for highway cruising, maybe 1-2 for city driving.
Now for the bad.
It's ugly in the engine bay. It complicates the intake chambers (inefficient PCV + exhaust gases = really dirty top end over the long run).
It adds weight.
In stock form adds an obstruction in the intake.
When you get a cam for your LSx car, you can pretty much get rid of it. Most cams from 01-02 to a lot of aftermarket have enough overlap in it to pretty much allow for self EGR by the cam in a sense and still retain the ability to get timing and lean conditions without blowing up the car during cruise.
Mine's disabled, but due to emissions, I have to keep appearance of it there. The only thing I wish I still had working is the AIR system believe it or not. That choking rich smell on initial startup when cold bugs the hell out of me. Oddly my 07 Monte Carlo SS also has such a rich smell on initial startup too despite having air in it.
First is lower combustion chamber temps. This is TRUE. What happens is that during part throttle (which is what MOST of our cars spend it's life in) is that it recirculates combustion chamber gases back into the intake stream. Combustion chamber gases have bits of unburnt fuel but the majority of it cannot be reburnt. This has the effect of altering the air fuel mixture in such a way that the combustion reaction is slowed and the combustion temperature reduced. It's significant enough that NOx particles cannot be created.
For example typical NOx production occurs at a combustion temperature in the 1500F range. EGR can reduce it a few hundred degrees to deter this from occuring.
Now something else can be done as well. For extended crusing, the timing can be advanced significantly. The effect is that more timing and less fuel can be used. The end effect is worth as much as 2-4 mpg for highway cruising, maybe 1-2 for city driving.
Now for the bad.
It's ugly in the engine bay. It complicates the intake chambers (inefficient PCV + exhaust gases = really dirty top end over the long run).
It adds weight.
In stock form adds an obstruction in the intake.
When you get a cam for your LSx car, you can pretty much get rid of it. Most cams from 01-02 to a lot of aftermarket have enough overlap in it to pretty much allow for self EGR by the cam in a sense and still retain the ability to get timing and lean conditions without blowing up the car during cruise.
Mine's disabled, but due to emissions, I have to keep appearance of it there. The only thing I wish I still had working is the AIR system believe it or not. That choking rich smell on initial startup when cold bugs the hell out of me. Oddly my 07 Monte Carlo SS also has such a rich smell on initial startup too despite having air in it.
02-26-2008, 04:57 PM
#22
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Thank you SladeX. I did read that sticky and was still confused. I'm not rying to be a dick. I just don't understand what the big deal is about not having your questioned without searching. I don't know I always just thought it was the purpose of a forum to ask questions.
02-26-2008, 05:11 PM
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Thank you SladeX. I did read that sticky and was still confused. I'm not rying to be a dick. I just don't understand what the big deal is about not having your questioned without searching. I don't know I always just thought it was the purpose of a forum to ask questions.
02-26-2008, 05:18 PM
#24
I've been through the stickies and if I feel it's something simple and easy to answer, I will point out stickies as well.
Though I wonder how many read the stickies and REALLY understand what each part means.
I think it's great to ask questions and as long as it's not too simple I think you should continue to ask, worst case is you'll be pointed to a sticky that covers it well enough. If not, there are others like myself that will answer as best we can. This is really a great place to learn and given time and funds you can learn a lot about the best ways of going about getting to your goals. I know my current project car is short some heads. Anything else after that is strictly weight loss type mods but thanks to this forum, I made a car that fits the way I like to drive and thanks to it has actually saved my life a few times (better handling mods + added power to do things normal cars/stock cars wouldn't have pulled off).
Though I wonder how many read the stickies and REALLY understand what each part means.
I think it's great to ask questions and as long as it's not too simple I think you should continue to ask, worst case is you'll be pointed to a sticky that covers it well enough. If not, there are others like myself that will answer as best we can. This is really a great place to learn and given time and funds you can learn a lot about the best ways of going about getting to your goals. I know my current project car is short some heads. Anything else after that is strictly weight loss type mods but thanks to this forum, I made a car that fits the way I like to drive and thanks to it has actually saved my life a few times (better handling mods + added power to do things normal cars/stock cars wouldn't have pulled off).
02-26-2008, 06:32 PM
#25
an egr does not really affect performance per say. your car is not going to be way faster
cause its gone. in the same breath i am not a fan of how they can coke up an intake and
the back side of a throttle body.
air is only on in open loop it sends oxygen thru the exhaust to help burn the unburned fuel until the cats get hot enough to light off. open loop till 142* i belive.
now the best use of an air pump i learned on this board, it was a cammed car that had to do califs treadmill test. running it off a toggle switch. yeehaw theres somebody thinking on there feet
cause its gone. in the same breath i am not a fan of how they can coke up an intake and
the back side of a throttle body.
air is only on in open loop it sends oxygen thru the exhaust to help burn the unburned fuel until the cats get hot enough to light off. open loop till 142* i belive.
now the best use of an air pump i learned on this board, it was a cammed car that had to do califs treadmill test. running it off a toggle switch. yeehaw theres somebody thinking on there feet
02-26-2008, 07:40 PM
#26
Z Fury: Here is the thing you gave me a sticky for a third gen vechicle. I have know need to look in there so i never saw it.
Also isn't the point of a forum to post a question and get an answer not to have someone tell you to do a search, if I wanted that I would use google. If your to lazy to answer the question and tell someone to search then just don't post. I get tired of people telling others to do a search. Just answer the question for the person.
Also isn't the point of a forum to post a question and get an answer not to have someone tell you to do a search, if I wanted that I would use google. If your to lazy to answer the question and tell someone to search then just don't post. I get tired of people telling others to do a search. Just answer the question for the person.
And for the record, at no point did I ever say "USE THE SEARCH, DUMBASS" or anything of that nature.
EDIT - I'm not sure if anyone else mentioned it, but the LS1 engine is considered a Gen III engine, and that is why the sticky for this is listed there. The LS2, LS3, and LS7 are the Gen IV engines. I think you have that confused with the car's Gen label. I did the same thing when I first started lurking here too.
Last edited by Z Fury; 02-26-2008 at 07:46 PM.
02-26-2008, 08:29 PM
#27
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Thanks for all who posted learned a lot. Also does any one have a picture or can describe what the AIR thing actually looks like because I have headers that the guy before me put on and also no cats. That being said I should have no need for AIR right? I have looked for it but I don't know what I'm looking for so I don't know if its there... I know I still have ERG because I can see the ugly thing. Can you have EGR and not AIR?
02-26-2008, 08:42 PM
#28
Yeah the AIR can be taken out and not the EGR. Personally I still have both despite not being used.
Here's a link to air removal with pics so you know where they would be.
https://ls1tech.com/forums/generation-iii-external-engine/673299-air-removal-pics.html
Regardless of whether or not you have headers, if you have AIR, then the tubes on the sides of the headers will be connected to a hose that will snake its way around the engine. It will go to a box in the driver's side tucked into the front/driver's panel area at the front of the engine bay.
Here's a link to air removal with pics so you know where they would be.
https://ls1tech.com/forums/generation-iii-external-engine/673299-air-removal-pics.html
Regardless of whether or not you have headers, if you have AIR, then the tubes on the sides of the headers will be connected to a hose that will snake its way around the engine. It will go to a box in the driver's side tucked into the front/driver's panel area at the front of the engine bay.
