Egr

[fbaurley]

Is Egr something we are going to have to live with on the cummins from here on out beginning in 2004. or is it just a quick fix to meet emissions while they are working on better engine controls.

 

[nickleinonen]

in my opinion, it is just a quick fix until the newer gen camless diesels come around. the camless design can allow for no egr at all... [as can variable cam shafts if it is a dohc, like the gm 4. 2I6 gasser, but camless will be better] the egr valve was introduced into automotive world in the 60-70's... way old tech. and you want that on a year 2kx model engine? it's a step backwards i think

 

[DocStressor]

The EGR system in modern diesel engines is quite different from automotive EGR. EGR in a gas engine is simply a way to vent crankcase vapors back into the engine for re-combustion. The cooled EGR system in a diesel is designed to reduce NOx emissions by lowering combustion temperature. This is accomplished by carefully metering a small amount of cooled exhaust gas back into the cylinders during the compression stroke. This lowers the combustion temperature and those minimizes the formation of oxides of nitrogen. There is a small lose in efficiency (power and economy) as a result. The advantage of cooled EGR is that it is pretty much a bolt on solution for engines with computer controlled injection. The downside is soot accumulation in the oil and the intake system. The oil problem has largely been solved by the CI-4 standard. Until ultra-low sulfur diesel fuel becomes generally available after 2006, there are likely going to be intake manifold problems base on what people have seen with the Volkswagen TDI engine.



There are other ways to reduce NOx without EGR. All require a better fuel than we have available at present. I agree that EGR is a short term solution until the next generations of diesel engines are designed and manufactured. Engineers have a notty problem since improving combustion efficiency generally requires higher compustion temperatures. This reduces CO and particulates but increases NOx. as a consequence.

 

[jimnance]

Caterpiller has come out with what they refer to as ACERT technology. It does not reley on EGR. Instead it is a combination of computer control injection and a catalyst to reduce soot and hydrocarbon emissions.



It is supposed to be a better long term solution, but as yet is unproven.

 

[rbattelle]

Someone correct me if I'm wrong, but Lee's description of EGR is accurate for BOTH gasoline and diesel engines. Gas engine EGR does not simply plumb crankcase gases back to the cylinder, it dumps exhaust gases to the cylinder. Crankcase cases are also fed in, but it's done via the PCV valve and crankcase breather element (which is mounted somewhere in the air cleaner housing).

 

[fbaurley]

So if it is just a bolt on sloution You should just be able to un bolt it right, or change the intake manifold to one that is from an offroad engine, and then reprogram the ecm, and thumb your nose at the EPA.

 

[nickleinonen]

Originally posted by rbattelle

Someone correct me if I'm wrong, but Lee's description of EGR is accurate for BOTH gasoline and diesel engines. Gas engine EGR does not simply plumb crankcase gases back to the cylinder, it dumps exhaust gases to the cylinder. Crankcase cases are also fed in, but it's done via the PCV valve and crankcase breather element (which is mounted somewhere in the air cleaner housing).

you are right. the pcv [positive crankcase ventilation] valve is what allows the crankcase fumes/vapours to be burned off. there are diesels that have pcv type systems. if you have one of those, and an egr, well, that is nothing but trouble. if you want to try a little experiment, scrape some soot out of your tailpipe into a clear 35mm film container, then add a few drops of oil to it. . mix it and see what you get. it is pretty much like vasoline. now imagine having that build up in your intake manifold. yummy isn't it. the egr system does reduce nox in both gasoline and diesel engines. in gas engines, it is designed to operate at light load so you have full power when you need it [and the egr system is off] in a diesel, it is suppose to be that way too, but under light load, the egt is pretty low, and not quite high enough to be breaking down the nitrogen to make the nox. at full load is when the nox happens, and if the egr system is "functioning" under full load, you'll have a similar result to having too much fuel, not enough boost [you could be reading 35psi on the gauge, but if the oxygen level in that is compromized by the egr system, it may only be like 22psi equal in the amount of oxygen in the fire] that also will cause smoke [say hello to diesel soot traps/cats :{ ] egt i am not too sure about in the full load condition. i am thinking it will go up, defeating the purpose of the egr system [high egt makes nox]. reason i think it will go up is just like not enough boost for fuel. temp goes up... i'm still going to stick to my belief that egr's are mickeymouse by design.

 

[rbattelle]

Although the idea of EGR is good in theory (reduce cylinder temperatures, which reduces emissions and knock tendency), I believe the costs (extreme deposit formation, for one) far outweigh any benefit.

 

[jimnance]

Fleet managers have put off buying new trucks resulting in thousands of layoff's because of the new unproven EGR technology required by the government.



Without question it reduces fuel economy to some degree. The number seems to vary, but somewhere between . 2 and . 5 MPG comes to mind. Keep in mind if pre-EGR fuel economy for a big truck fleet was 6. 5 MPG that represents a significant increase in fuel costs.



Reliabiility is also a big concern. Many purchasers are sitting on the fence to see how well the new technology works out. Some fleets are putting on 200,000 plus miles per year on a unit, so in a couple of years they will have an idea how well they are holding up.



That was one big reason I bought my '03.

 

[Bill Stockard]

It will be interesting to watch the new 6. 0L Powerstroke to see how it works out. It has both cooled EGR and an electronicaly controlled variable output turbo which we will have after Jan 1 2004. So far other than the usual new engine introduction "bugs", it has more power, is much more responsive to the throttle, and is getting better fuel mileage than the previous 7. 3L Powerstroke. It will be interesting to see how much maintenance is required to accumulate 100K+ miles... . Yeah, I know what the book says.



Bill

 

[nickleinonen]

It has both cooled EGR and an electronicaly controlled variable output turbo which we will have after Jan 1 2004.

does cummins get the variable geometry turbo in the 01/01/2004 models?. i know we have that blasted unforgivable egr system, but the variable turbo sorta makes up for it if we get it.