EGR and the GM 4.3l

[George7941]

What is it about the 4.3 (and other Vortecs) that enable it to meet emission standards without EGR? The engine design goes back decades, and it is not a high tech engine with variable valve timing or anything like that.

I am not complaining, I am glad I don't have to deal with a EGR system. They can be troublesome.

The only complaint I have about the 4.3 is that it is not particularly fuel efficient.

 

[bepperb]

My Accord has EGR and the Highlander doesn't besides being otherwise pretty similar. But what I'm trying to say is that I don't think EGR is necessary for a modern engine to meet emissions. The Accord gets much better mileage in the real world.

 

[George7941]

EGR may not be necessary but it is one of the tools to reduce Nox. The Vortecs are reducing Nox some other way. Dunno if a highly efficient catalytic converter can reduce Nox to acceptable levels.

 

[Chris142]

Does vehicle weight determine what emission controls an engine gets? Weight used to be a major factor in that. Some 1-ton trucks didn't get cats untill the late 80's due to the GVW.

Maybe the weight of the van puts it in a different emissions catergory?

 

[xxch4osxx]

My 2004 Silverado 4.8l v8 doesn't have an EGR valve either and passed the emission test back in November with flying colors. I am curious as to why most vehicles have them yet my truck doesn't and passes emissions tests so easily.

 

[endeavor to persevere]

Originally Posted By: xxch4osxx
My 2004 Silverado 4.8l v8 doesn't have an EGR valve either and passed the emission test back in November with flying colors. I am curious as to why most vehicles have them yet my truck doesn't and passes emissions tests so easily.


GM did away with EGR on the trucks when they went to drive by wire on the 03 models.

 

[xxch4osxx]

Originally Posted By: endeavor to persevere
Originally Posted By: xxch4osxx
My 2004 Silverado 4.8l v8 doesn't have an EGR valve either and passed the emission test back in November with flying colors. I am curious as to why most vehicles have them yet my truck doesn't and passes emissions tests so easily.


GM did away with EGR on the trucks when they went to drive by wire on the 03 models.
Ah, I see, thats good, one less thing to go wrong, lol. How did they get them to pass emissions requirements though?

 

[artificialist]

Better combustion chamber designs enable the fuel/air mixture to be consistent within the cylinder. Port designs with more swirl might also be a factor as well. That contributes to less NOx. Another thing that reduces the need is more even cooling to prevent hot spots which create NOx.

 

[mechanicx]

It's hard to figure that a iron head wedge mpotor wouldn't need an EGR to meet NOx emissions. You could see it on a aluminum 4-valve with cam phasing. I don't know if pick ups are allowed to meet a lower standard or not. The valve timing/camshaft choice probably plays a rule in NOx and other emissions.

 

[Herz]

Originally Posted By: endeavor to persevere
Originally Posted By: xxch4osxx
My 2004 Silverado 4.8l v8 doesn't have an EGR valve either and passed the emission test back in November with flying colors. I am curious as to why most vehicles have them yet my truck doesn't and passes emissions tests so easily.


GM did away with EGR on the trucks when they went to drive by wire on the 03 models.


I was just about to say my 02 has a EGR haha.

 

[xxch4osxx]

Originally Posted By: mechanicx
It's hard to figure that a iron head wedge mpotor wouldn't need an EGR to meet NOx emissions. You could see it on a aluminum 4-valve with cam phasing. I don't know if pick ups are allowed to meet a lower standard or not. The valve timing/camshaft choice probably plays a rule in NOx and other emissions.
My 4.8 has aluminum heads

 

[artificialist]

Originally Posted By: xxch4osxx
Originally Posted By: mechanicx
It's hard to figure that a iron head wedge mpotor wouldn't need an EGR to meet NOx emissions. You could see it on a aluminum 4-valve with cam phasing. I don't know if pick ups are allowed to meet a lower standard or not. The valve timing/camshaft choice probably plays a rule in NOx and other emissions.
My 4.8 has aluminum heads

4.8/5.3 have aluminum heads.

Every 4.3 has iron heads.

 

[SteveSRT8]

add the 6.0 GM to that list. They all are the same family.

And the remark about cam having an effect on NOx is right on. For example the 5.7 Chrysler V8 has EGR and the 6.1 does not. This is due to aggressive cam specs on the 6.1 where the overlap is actually the same as EGR, allowing some mixture dilution at low engine speeds.

 

[artificialist]

Originally Posted By: SteveSRT8
add the 6.0 GM to that list. They all are the same family.

And the remark about cam having an effect on NOx is right on. For example the 5.7 Chrysler V8 has EGR and the 6.1 does not. This is due to aggressive cam specs on the 6.1 where the overlap is actually the same as EGR, allowing some mixture dilution at low engine speeds.

Some versions of the 6.0 had an iron cylinder head.
That is why I didn't list it.

However, that version was made years ago.

 

[SteveSRT8]

sorry, I've owned dozens of them and never had an iron head on one.

Wonder what vehicle that was used in?

 

[JTK]

GM definitely made many intake manifold, fuel management and emissions changes to the 4.3L over the years. I don't recall our 1990 having EGR, but it did have a 'smog' pump to blow air into the exhaust manifolds. My 1994 and 1998 4.3's both had EGR systems. I've never heard of electronic throttle eliminating EGR, it's usually a valve timing or variable valve timing systems that eliminates it.

Joel