[crash70rs]

A few years ago the emissions controls on my car got uhh.. misplaced . So now I'm thinking of putting some back one of which is the EGR. This is of course in an attempt to be able to pass NYS emissions.

The first question would be is it worth it?

I understand what it does and why, what I'm a little fuzzy on is when it works. I know it should be close when the engine is cold or at idle. When should it be open? At part throttle with little load (cruising) or high load (going too fast)?

I would likley need to modify an intake for this, since as of now I haven't found one that will work for me. But all I would need to do is provide a path into the intake stream? nothing special there right?

And finally if you made it through all that, any recommendation on an egr? The stock one fot the car is vaccum controlled but I think I may want one that electrontic, so I can have more control of it. (I'm not afraid of sparks).

Thanks! CRASH

[Jmark]

"Most" EGR's work under load and off idle. "Most" have the vac. hose running through a thermal vacuum switch so it's not active when the engine is cold.

Trying to make one work on a non-egr intake will be difficult at best.....or just plain not gonna make it. The exhaust gasses must have a source and then be metered at some pre-determined amount and then introduced into the intake stream evenly to all cylinders.

As far as trying some kind of electric switch to activate it,,,,,ummm,,,,,,,well......probably not gonna work too good either.

Don't know how New York's emissions work, but here in Arizona, it states "As installed by the FACTORY". Hanging stuff here and there and saying it works doesn't cut it here.

What engine do you have now and what intake is on it?

Mark

[crash70rs]

Yea, Thats the type of answer I figured. Currently I'm running a 355, in place of a 305. with a hyd. roller cam (can't recall specs now). I'm currently collecting part to put together a MegaSquirt TPI set-up.

It will likely have a Holley EFI intake on it, but that does not have provisions for an EGR.

Getting a source of exhaust is easy, just tap into the headers.

Doesn't the egr itself act to meter the exhaust? I would think (I may be wrong) all I would need is a valve appropiatly size for the displacement.

I know this isn't the correct way of doing things (the correct way would be going back to stock..and thats no fun), But my understanding for inspection is if it is there and looks like it works then it's passes. The main purpose will be to pass the NoX part of the sniffer test.

I would not just rig it up i would do my best to make it look like it belongs.

[Chevrolet4x4s]

Go to a shop way way out in the sticks and adjust your carb way lean ....rich enough to run for the test.Then put it back to normal after you get your sticker
Shane

[Jmark]

Originally Posted by Chevrolet4x4s

Go to a shop way way out in the sticks and adjust your carb way lean ....rich enough to run for the test.Then put it back to normal after you get your sticker
Shane

That may work providing they don't look under the hood or under the car. Here in AZ, they ck everything that the car had when NEW and it MUST still be there and operating correctly.

[crash70rs]

I found an accel intake manifold with provisions for an egr valve. If i replace the stock 87 monte EGR (305 HO) will that be sufficient?

It's a little pricey, I think it would still be cheaper for me to mod one.

[redsdad]

Originally Posted by crash70rs

Doesn't the egr itself act to meter the exhaust? I would think (I may be wrong) all I would need is a valve appropiatly size for the displacement.

The EGR dilutes the air fuel mixture by adding exhaust gas to the intake stream under certain conditions. The idea is that by diluting the intake stream, you have less potential chemical energy in the combustion chamber. This reduces the combustion temperature when the mixture is ignited. NOx emissions are created when air (approx. 75% nitrogen) is exposed to high temperatures. The high temperatures break the N2 bonds and the individual nitrogen atoms recombine with oxygen atoms to form NOx (NO2 and NO3 IIRC). By lowering the temperature, you reduce the amount of NOx emissions. IIRC, NOx combines with water in the atmosphere to produce acid rain and it reacts with trees and other plant life to produce the greenish haze component of smog.

I haven't studied how they determine the orifice size on the EGR valve, but my guess would be that it is determined by vehicle weight and engine displacement. Since you have changed things, you may have a problem getting the correct valve. Too large an orifice, and you will kill more power than you need to. Too little, you may not pass the NOx test (you may want to see if they actually check for NOx - you might want to put the valve on with a block off plate under it if all they do is a visual check). If a 350 was offered for you year and model, I would use that one as a starting point.

BTW, leaning the carb out can actually increase combustion temperatures and may increase the NOx output. An overly lean condition can also push up HC emissions due to misfires.

[crash70rs]

Thanks for the reply, very helpful.

I know in the NY metropolitan area (where the vehicle is currently registered) they are supposed to do just a visual inspection of the emmission equiptment.

Then the vehicle is put on a dyno (not one that'll tell you HP) for the "high advanced emissions test. This simulates various driving conditions with a sniffer in the pipe looking for HC, CO, and NoX.

However where I am currently living I know they must do a visual inspection, but the sniffer is only at idle.. so the EGR would not be functioning anyways.