how does the egr cool????? 200 degree exhuast gases... or 70 degree air from outside....

 

If the coolant is termally "saturated," it wont absorb any of the heat (energy/power). The heat and engery has to go somewhere... and it will go into smashing that piston down faster. I think thts why fred was getting at???

 

yeah its 200*, but combustion temps are severl times that.
It displaces air that could burn. so less gas. less gas to burn with same a/f ratio = less engery going in, less coming out(heat)


kind of like making the engine have less displacement. the egr is just dead air, it just takes up space that oxygen would normally combust in

 

but don't you need that oxygen for a complete combustion?
i thought we blocked off egr for performance in our cars?
if you use antifreeze and not just water like me... the coolant won't saturate until like 300 degrees i believe

 

Trey:

You have to understand that they are trying to control three different pollutants. Two of the pollutants are "oxygen deprived".... unburned hydrocarbons (HC) and carbon monoxide (CO). These form when combustion is not complete. They are probably a lot more sensitive to A/F ratio than to combustion chamber temps. "Rich" makes for HC and CO. They will complete the oxidation reaction better at higher temperature. Oxidation of HC and CO is good.

But the third pollutant is NOx, and NOx works just the opposite of HC and CO.... it has too much O2. Formation of NOx is promoted by higher combustion temperatures and by higher oxygen content. "Lean" makes NOx. Oxidation of nitrogen is bad.

So.... raise the temperature to complete the combustion of HC and CO. Then quench (lower) it when it gets too high, to prevent the formation of NOx. And, its the odd combination of moderate load and low RPM - lugging the engine up a hill in too high a gear - that generates the high combustion chamber temperatures. Surprisingly, that's a higher combustion temperature/residence time situation than WOT/max load/high RPM. Not sure if I could explain why.

 

The reason GM would intentionally make cars overheat is job security. If you buy a car and never have to do anything to it they make that initial profit of selling the car and thats it. But then if you go buy new heads because yours warped from overheating or have to take your car in to a GM dealership to fix the head gasket then they keep making money after the fact. Not a big deal but they want to keep making money off a car for as long as possible or want you to get sick of fixing your car and buy a brand new one from them.

 

absolutly not. Gm wants to make reliable car. in the words of eric bryan- product is king. GM is not in the position, and knows it, to make unreiable cars on purpose.


its not FILLING up the cylinder with inert gasses. just some as fred explained.

If you block off the EGR, you dont have this exhuast in there "taking up space" and you can put air in there that will burn

 

Exhaust gasses displace air, and fuel rate is reduced correspondingly. As Trey points out, there is less fuel, less BTU's produced, lower temperature.

AND.... the combustion temperatures are also a function of the PERCENT O2 in the combustion chamber. Reduce the %O2 in the chamber and the combustion is more "controlled" and at a slower rate. Increase the %O2, and you increase the burn speed and the combustion becomes less "controlled". Nitrous (N2O) increases the %O2 in the combustion chamber, and speeds the burn rate. That's why you need to pull timing with nitrous... the combustion is faster. And the combustion temperatures increase. Try using pure O2 instead of N2O...... .

 

i'll stick to nitrous... it would explode or catch on fire

 

First of all, you need to read. I never said coolant runs through the lt1 intake, I said RADIANT HEAT to the intake.

( Although Coolant actually does go to the throttle body!) But again I was talking about radiant heat.

As far as the computer retarding timing in relation to coolant temp I'm NOT stating fact on that, so i will let someone else chime in. ( I actually had in mind how some programs like Hypertech use more timing with lower temp thermostats.) But anyways, radiant heat from the engine can increase intake maniflold and tube temps which I am almost certain will cause the computer to pull timing due to Higher IAT's.

You stated that the LT1 does not have coolant going throught it . I NEVER SAID IT DID! ( Although again, the throttle body does, and that is why some bypass it.) But I did not say coolant goes through the intake.

I said RADIANT HEAT would/could cause intake temps to increase (Ever notice how hot an lt1 intake is after you drive?), I Never said coolant running through the intake, or that there was coolant running throught the intake.
Pay attention.

The ideal would seem to be a WARMER engine temp for more complete combustion,(if you can keep the intake air cool) with a COOL intake charge. In cases where you see more power with low engine temps, it's most likely because of more timing being used because . NOT BECAUSE A COOL BLOCK or LOW COOLANT TEMP MAKES MORE POWER.

But again, IF you can control for this, and you can keep your INTAKE air cooler you could still keep more timing anyways , even though the engine temps might be warmer.

Anyways , you should read first, and have some Idea before you reply. And again, I ask like the person above what is silly about the post?



AND READ before you reply this time.

 

You need oxygen for complete combustion. When the EGR system is activated, the exhaust gas replaces some of the O2. AND the PCM knows the EGR system is activated and reduces the amount of fuel it adds, to maintain the resired A/F ratio.

No.

You don't gain anything in the way of performance by blocking off the EGR. The EGR system only operates at part throttle. It never operates at WOT, so it has absolutle NO effect on performance, whether it is there or not.

You could speculate that there is some small temperature reduction in the intake manifold in the area of cyls #7 and #8, that nets you a slightly denser charge in the cylinders when there is no EGR heat connected to the intake manifold, but that's really a stretch.

You'll have to explain the meaning of "saturate"... not sure what you mean.

 

TRUUUUUE THAT. Lol

 

certain liquids are only chemically capable of holding a certain temperature.... and they cannot be heated beyond that... for instance if you tried to instantly raise the temperature of a gallon of water from 100 degrees to 300 it would "superboil" water, in its liquid form cannot be raised above the boiling point of 212 degrees F. when it does... it turns into steam... however when its in a sealed enviroment (like your cooling system) with no air present, and unable to expand into a gas because its under pressure... the liquid saturates... and is unable to absorb and more energy or heat because it has reached its tilt...

 

Thanks goodness! Injuneer to the rescue.


Suddently my post does not look so silly now, huh Treyz28.

My post basically is the same information Injuneer just gave, that a Warmer engine = more power from complete combustion, as long as intake temps are kept cool, and that it's mainly the timing that causeses an increase with lower coolant temps. Not a COOL BLOCK. RADIANT Heat is what can hurt if it gets to the intake air. I did NOT say there is coolant in the intake, (HOWERVER, again it does go through the throttle body). If you can keep the intake cool , a warmer engine is better for power. Plus you can add timing with cooler intake air.

Also notice the last part of his. I'm not an expert on the stock computer, but the idea of timing retard for a when coolant temps increase in not so silly.

 

by reading your post, i got the impression that that you were saying the pcm retards timing when coolant temps increase, afterall- we WERE TALKING about coolant temps and performance
Now we can sit here and argue who miscommunicated or who misunderstood- while you continualy say the same thing 18x in post ("RADIANT!") or we can give it up and move on with life.

Personaly, i chose the second. my ego is not so big that its going force me to sit here and argue with you. Personnaly, i think your explanation was confusing at best compared to freds explanation.

anywho, thanks fred for clarification, explaination and the emissions thing