EGR Delete Question??

[windrunner408]

I am curious about the effects of doing an egr delete on the motor. I realize that by deleting the EGR system you remove the possibility for it to fail but what effect does removing the exhaust gases that are recirculated to the intake have on the motor performance wise??

I didnt think about these things when i did my egr delete about a year ago but what I did notice when I deleted my egr cooler, oil cooler, added a RR kit, added a spearco intercooler, and modified my 5in exhaust to go to an 8in stack was that it now appears that my truck runs at slightly higher boost levels than it did before these modifications, resulting in lower fuel economy. And by that I mean 19-20 on the hwy to 17-18 on the hwy.

So I went looking for the culprit and the only thing that seems to make any sense of what could cause this was the deletion of the egr system.

My theory (and I would like your input) is that since the EGR system is gone the engine now requires more air to get the same power recipe (mixture of air, fuel, and whatever else) as before the delete. It has been proven already that diesel engines respond very well to just about any type of fuel augmentation; whether it be propane, water/meth, nitrous (more air), natural gas, or even gasoline (check diesel power mag).

So I am thinking that the recirculation of exhaust gases, in a way, acted like a type of fuel augmentation and when I deleted that, I in turn lost some performance. What are your guys' thoughts on this??

[PGreenSVT]

You are off 180* on your thinking here. The gasses recirculated are essentially spent (inert) from an energy perspective having no usable O2 to make power. It is added back into the combustion cycle to lower emissions because it essentially lowers the output of the engine.

Here is a hypothetical example for purpose of explanation. Stock engine cruising 65mph is running on 70% fresh air and 30% recirculated exhaust. Since the computer Knows this it is fueling the truck to burn the 70% O2 and not adding fuel for the spent egr gasses. So our cylinder charge is actually only 70% of capability. Less fuel, lower temp cylinder charge due to 30% inert charge and lower fueling level.

Now the egr deleted truck is running along at the same 65mph BUT since the egr delete it doesn't get any spent recycled exhaust gasses. Cylinder gets filled 100% with fresh air due to egr delete. Computer Knows this and fuels for this 100% charge by adding fuel to burn the additional 30% O2. Result is more power from 100% cylinder combustion resulting in higher temps due to the add'l O2 and fuel. EGT's are up slightly and fuel mileage is down a bit.

BUT you are no longer adding sooty exhaust to the intake and cylinders which will keep the carbon deposits in the combustion chamber down. Less carbon buildup on top of your pistons. Your engine should stay healthy and clean longer.

Hope that helps.

[windrunner408]

I was hoping you specifically would chime in, because if anyone knew about these effects I was thinking you would.

I see what you are saying and that makes sense. I also agree with and forgot to mention in my previous post the benefits of not having that sooty junk build up in both the intake and motor.

So am I correct in saying that by deleting the EGR system on my truck, that is the reason why I am seeing the higher boost levels?

Also, I guess now in order to regain my lost mileage back I have to increase the intake efficiency such as with a gogo intake manifold. This way if I am flowing more air for a certain level of boost then by increasing that airflow I can keep the same level of airflow required by the engine and in turn lower my boost, which should increase efficiency and raise fuel economy. Right?

[the chad]

I noticed slightly higher boost (1-2 psi) and faster spool up with mine as well.

[windrunner408]

Good to know. You know i am probably making a big deal out of nothing (tend to do that sometimes) the boost levels are right about where they were at when the truck was completely stock before any of my mods.

I am not sure if this is related or not but something I also have never noticed before installing the egr delete is that now whenever IATs get over 85*F, the truck will raise the boost level on me. PGreen any ideas??

[PGreenSVT]

I haven't paid that much attention to the details on my truck. As long as my numbers are all reasonable I don't worry about it. I am sure my egt's went up a bit with the egr delete but I don't usually do one thing at a time so I can say that this particular mod resulted it this outcome. When My egr delete went in my truck was studded and the FICM replaced and updated to the VXCF9 code at the same time.

I can tell you EVERY mod I have done I have lost fuel mileage and currently average 12.4 mpg. Then again I don't drive with fuel mileage even a remote consideration.

Your thought on the Gogo intake is reasonable. Since it flows better than stock you should make the same power with a little less boost. The big difference is it will equalize airflow across the cylinders balancing the power output.

[windrunner408]

Got ya. Good to know on the gogo intake. While increasing fuel economy isnt my number one concern, I surely dont want to really lose fuel efficiency if I can help it.