LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

what does secondary air injection do?

Old 07-19-2006, 08:05 PM
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what does secondary air injection do?

I took apart my lt1 to replace the lifters and valve springs and i figured that while i had the engine out I would replace all the gaskets cuz they leaked some. anyway, i pulled the motor (from the bottom) and the pipe that comes from the header to the back of the intake had been pinched and had broken in two. the back of my intake was really black so it had been that way for a while. can i just block off the ports on my intake and header and leave the pipe off or should i get a new pipe.
what does secondary air injection do?
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Old 07-20-2006, 08:14 AM
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Re: what does secondary air injection do?

The corrugated tube that runs from the #8 primary to the back of the intake has nothing to do with the secondary air (AIR) system. That's the riser tube for the EGR system. If that was cracked and leaking for an appreciable period of time, there's a very good chance it was causing the passenger bank of the engine to run pig rich, and possilby pulling in enough air to cause a burnt exhaust valve.

You either need to replace the tube, or delete it, using blocking plates over the hole in the header and in the intake manifold. If you block it off, the EGR system will no longer flow, possibly causing a code and an SES light. EGR is used to reduce combustion chamber temps, to limit the formation of oxides of nitrogen (NOx). It also helps reduce the possibility of detonation under high combustion chamber conditions..... typically lugging the engine at low rpm in the wrong gear.

Blocking plates:

http://sjmmanufacturing.com

EGR system components, courtesy of Shoebox:

http://shbox.com/1/egr1.jpg

Just curious....you took your engine out to replace the lifters and valve springs?????
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Old 07-20-2006, 05:08 PM
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Re: what does secondary air injection do?

Originally Posted by Injuneer
... EGR is used to reduce combustion chamber temps, to limit the formation of oxides of nitrogen (NOx). It also helps reduce the possibility of detonation under high combustion chamber conditions..... typically lugging the engine at low rpm in the wrong gear. ...
I'd prefer not to hijack someone else's thread, but I couldn't resist, since it's on topic.

Fred, just how much does the EGR come into play at low revs in terms of reducing detonation? I'm sure few have studied this enough to quantify it, so I'm looking more for your opinion/guess. With an engine such as mine, using quality 93-94 octane gas, occasional racing but mostly street driven with a lot of low RPM cruising - is there any real benefit to having a functioning EGR? I realize that there is no drawback to EGR, but mine wasn't working so I blocked it off and had it programmed out. I'm just wondering if it would be worthwhile to fix the EGR and have it working.

Thanks.
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Old 07-20-2006, 06:06 PM
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Re: what does secondary air injection do?

^ I deleted my EGR and cruise around at like 950-1000rpms in 6th gear alot and havent experienced detonation yet. Cars way back when did not have EGR and worked just fine.
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Old 07-21-2006, 05:21 PM
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Re: what does secondary air injection do?

yes i took it out to do that. I wanted to replace the leaky gaskets and I didn't want to kill my self doing it. i just thought that i could do a better job if it was easier to work on. also i bought the car a year ago and i knew that it had a rebuilt engine and i wanted to check everything out.

turns out that it has h-beam rods, fully balanced rotating assembly (it was pretty), je flat tops .030 over, arp main studs, and arp bolts throughout, comp cam 233int/238exh @ .050 .528"int. .536" exh, comp pro magnum RR's(1.6), 7/16 studs, 7.100 pushrods, ported heads, 2.1" intake 1.6"exh stainless valves, spec stage 3 clutch, high torque starter, spicer aluminum driveshaft, LT headers (not sure on brand), moroso CAI, 4.10 gears in rear, and more all for $5,100

where can can i get that pipe. whenever i go to o'reilly's they just stand there and stare at their screen for five minutes then say go to the dealership
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Old 07-21-2006, 05:23 PM
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Re: what does secondary air injection do?

Damn you sure got to find out alot about it quickly LOL

Nice Try Jason Cromer, do a search for his # or look on shbox.com
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Old 07-22-2006, 09:47 AM
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Re: what does secondary air injection do?

I doubt that anyone can quantify the benefits.... and its not likely you would ever hear any detonation, because the PCM will retard the timing. Other than running a scanner and monitoring knock retard while lugging the engine under varying conditions, you wouldn't know if you had a "problem".

Cars "way back when" also may not have had the aggressive ignition advance, which gives the LT1 a performance level and fuel economy that is superior to the engines from "way back when".
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Old 07-23-2006, 12:57 AM
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Re: what does secondary air injection do?

Thanks for the info.
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Old 07-11-2017, 10:42 PM
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Re: what does secondary air injection do?

Originally Posted by crazydavez28 View Post
yes i took it out to do that. I wanted to replace the leaky gaskets and I didn't want to kill my self doing it. i just thought that i could do a better job if it was easier to work on. also i bought the car a year ago and i knew that it had a rebuilt engine and i wanted to check everything out.

turns out that it has h-beam rods, fully balanced rotating assembly (it was pretty), je flat tops .030 over, arp main studs, and arp bolts throughout, comp cam 233int/238exh @ .050 .528"int. .536" exh, comp pro magnum RR's(1.6), 7/16 studs, 7.100 pushrods, ported heads, 2.1" intake 1.6"exh stainless valves, spec stage 3 clutch, high torque starter, spicer aluminum driveshaft, LT headers (not sure on brand), moroso CAI, 4.10 gears in rear, and more all for $5,100

where can can i get that pipe. whenever i go to o'reilly's they just stand there and stare at their screen for five minutes then say go to the dealership


I would really appreciate your help as to where to loacte the part. The pipe.
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Old 07-11-2017, 11:53 PM
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Re: what does secondary air injection do?

Originally Posted by JaciEdd View Post
I would really appreciate your help as to where to loacte the part. The pipe.
Try posting in our "Parts Wanted" forum. So many people have deleted the EGR system that you may find someone who still has the parts laying around. Or try eBay.

https://www.camaroz28.com/forums/parts-wanted-39/

"crazydave...." hasn't signed into this site since 4-1/2 years ago.

Last edited by Injuneer; 07-11-2017 at 11:57 PM.
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