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#2373121 - 09/19/17 12:35 AM No EGR/EGR/Cam Overlap/Detonation, various questions
sycboi Offline
super stock

Registered: 09/18/03
Posts: 936
Loc: Norwalk, Ohio
Hopefully someone a lot more savvy at all this can clarify a few things for me...

The pre '09 6.1 Hemis did not have EGR systems. To keep detonation down the cam has more overlap designed into it's profile. I don't know any of what I just stated to be factual, it's just what I've read...

The early 5.7 Hemis had EGRs on the 1500 series trucks, but not on the heavier trucks. How did the non-EGR 5.7 Hemi keep detonation at bay? The non-EGR 5.7s used the same camshaft as the EGR Hemis, thus the same overlap for both. Something in the computer's tune? I cannot find any answers anywhere...

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#2373345 - 09/19/17 01:22 PM Re: No EGR/EGR/Cam Overlap/Detonation, various questions [Re: sycboi]
Medlock51 Offline
member

Registered: 06/15/16
Posts: 82
Loc: Wisconsin
I've seldom had detonation issues on any non egr engine... Burning spent gasses is never good for performance


Edited by Medlock51 (09/19/17 01:23 PM)

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#2373402 - 09/19/17 02:45 PM Re: No EGR/EGR/Cam Overlap/Detonation, various questions [Re: sycboi]
HotRodDave Offline
master

Registered: 01/29/05
Posts: 9416
Loc: Kalispell Mt.
It is not there for detonation, it is there to make al gore happy. The 3/4 ton trucks do not have to meet the exact same standards for emissions as 1/2 tons.
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#2373472 - 09/19/17 05:02 PM Re: No EGR/EGR/Cam Overlap/Detonation, various questions [Re: sycboi]
sycboi Offline
super stock

Registered: 09/18/03
Posts: 936
Loc: Norwalk, Ohio
I thought the EGR letting a bit of exhaust in actually helped cool the cylinder and helped keep detonation down? I'm not worried about losing a little HP as long as it'd help me keep my pistons from rattling and coming apart...
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#2373474 - 09/19/17 05:06 PM Re: No EGR/EGR/Cam Overlap/Detonation, various questions [Re: sycboi]
WO23Coronet Offline
master

Registered: 01/08/08
Posts: 3780
Loc: Canada
I think under light load part throttle scenarios it helps keep detonation at bay so you can run a bunch of timing, think Rick Ehrenberg preached this

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#2373502 - 09/19/17 05:40 PM Re: No EGR/EGR/Cam Overlap/Detonation, various questions [Re: WO23Coronet]
dogdays Offline
I Live Here

Registered: 01/20/03
Posts: 15717
NONONO!!!
E-berg said that use of EGR reduces the throttling losses because the engine doesn't have to suck in as much air, the exhaust gas takes up some of the space in the chamber. This is a fact, not just something that he said.

As for EGR, On Mazda's Skyactive Diesel they used a relatively low compression ratio. They were concerned about ignition. Their solution was to phase the exhaust cam so some exhaust gas was left in the chamber, warming up the mixture and assuring that it would light off with the lower, like 14.75:1, compression ratio.

The primary reason to use EGR starting in 1973 was to lower flame temperatures. Here's why: Starting that year there were stricter NOx limits. Most NOx that comes out the exhaust pipe is caused by nitrogen hooking up with oxygen and forming NOx starting at around 1500 degreesF. By adding the inert gas there was less air-fuel mixture (energy) in the chamber so temperatures didn't go over that temperature.

The Lambda-Sond system which started being used in about 1980 used a catalyst to cut down the NOx emissions, so EGR was used much less. The NOx catalyst only worked in a narrow band of air/fuel ratios and that's when the electronic control of mixture really began in earnest. It's all about the balance between CO, HC and NOx.

R.

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#2373565 - 09/19/17 07:36 PM Re: No EGR/EGR/Cam Overlap/Detonation, various questions [Re: sycboi]
HotRodDave Offline
master

Registered: 01/29/05
Posts: 9416
Loc: Kalispell Mt.
EGR is a stop gap emmisions device plain and simple, it would not be on modern cars if NOX emmisions were not regulated. It can not and does not help MPG or HP. It slows the burn speed and reduces peak temperature in the combustion chamber to keep from forming NOX. By slowing the burn you need to light the mix sooner to get to peak cylinder pressure at the same point in crank rotation, lighting the mix earilier than needed resists crank rotation not to mention the crank has to do more work compressing a gas in the cylinder that is not needed. Yes it can be used to keep knocking at bay, sort of like increasing octane... however it does it by displacing oxygen molecules that are needed to make a more powerfull combustion event. Why put big high flow cylinder heads desighned to flow lots of oxygen just to reduce the oxygen supply by flowing something else into the engine instead? Hands down one hundred percent of the cars I have tested blocking the EGR got better MPG without it, especially when tuned for its removal.

The bologna about how they can help MPG is just propaganda to try and make us feel like we are getting something for the extra money it costs to build a car with an EGR valve. Anyone with even a little bit of engineering minded common sense knows it takes more energy to pump more gasses through the engine and that a slower burn translates to worse MPG, also the same reason we dont get better MPG with 100 octane unleaded in a 77 440 than we do with 87 octane, it burns slower, needs lighted earlier, fights crank rotation more...

It is true for best mpg you generally want to advance the ignition timing more than stock but at a certain point it hurts instead of helps. Also an engine that mixes the air and fuel better and lights it off closer to the center of the chamber and burns it faster and more completly will see that advance point of optimum efficency get retarded not advanced more. A great example of comparison is a 70s low compression BB, they get best MPG with nearly 30 initial advance and closer to 50 total and they still did not make as much power or MPG as a modern hemi that gets best MPG with about 20 degrees total advance.
_________________________
I am not causing global warming, I am just trying to hold off a impending Ice Age!

68 cuda 360 notchback SOLD

1996 Ram 2500 5.9 eddy intake EQ heads, mild cam upgrade great tow rig!


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#2373738 - 09/20/17 12:11 AM Re: No EGR/EGR/Cam Overlap/Detonation, various questions [Re: sycboi]
383man Offline
Too Many Posts

Registered: 01/19/03
Posts: 26405
Loc: Balt. Md
EGR came about to lower combustion chamber temps to keep NOX levels at bay. It has been called the poor mans octane booster since it is inert gas that wont burn. As far as I have ever been taught in all my emission classes I took as a tech thats the main reason they use EGR which is to fight NOX levels. It was not used to stop spark knock and detonation even though it does help fight detonation. And I can tell you that in 1976 when I worked at a Ford dealer if the EGR vacum hose came off the EGR valve the eng would ping right away and when you installed the EGR hose back on the pinging would stop right away but thats because of how the engines were set to run with the EGR. And of course I cant see anyone with a performance car wanting an EGR system on it but I have seen some use it when they try to make the emission eng in their car a performance eng and run on low grade pump gas. The later year cat converter's were made as 3 way cats as they would control HC , CO and NOX as the first cats were called oxidizing cats and they only controlled HC & CO and used platinum or palladium in them. The later 3 way cats were called oxidizing and reducing cats as they added rhodium to the cat to help control NOX. I remember around 1992 some of the Mopar 3.3 engines stopped using the EGR because they used the 3 way cats and were said to have good enough emission controls to not need the EGR. But we had some coming into the dealer failing emission test in having to high of NOX readings. And many times we could not find any problems with them so Mopar told us to replace the cats as that was supposed to take care of the NOX. But with todays technology like quench and the combustion chamber designs of the modern aluminum heads and the right cam specs you can build a 10.5 comp performance eng to run on 91 pump and have no ping. Ron


Edited by 383man (09/20/17 12:12 AM)
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#2373749 - 09/20/17 12:49 AM Re: No EGR/EGR/Cam Overlap/Detonation, various questions [Re: sycboi]
sycboi Offline
super stock

Registered: 09/18/03
Posts: 936
Loc: Norwalk, Ohio
It sounds like I am going to be ok without the EGR as long as I have everything properly set up. I am having my computer flashed soon and needed to decide whether I was going to have the EGR enabled, or not.

I have a 2003 5.7 Hemi block with stock replacement pistons (.030" overbore) and a new Mopar stock camshaft for the 1500/2500 series trucks. I am going to run a 192 degree thermostat. I am going to only use 89 octane gasoline as well. Hopefully all that and a good cooling system will keep my engine running properly...
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#2373761 - 09/20/17 01:35 AM Re: No EGR/EGR/Cam Overlap/Detonation, various questions [Re: sycboi]
RTSrunner Offline
super stock

Registered: 11/03/03
Posts: 1173
Loc: Pittsburgh,PA
Sycboi,What is the application of your 2003 engine?

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#2373763 - 09/20/17 01:38 AM Re: No EGR/EGR/Cam Overlap/Detonation, various questions [Re: RTSrunner]
sycboi Offline
super stock

Registered: 09/18/03
Posts: 936
Loc: Norwalk, Ohio
Originally Posted By RTSrunner
Sycboi,What is the application of your 2003 engine?


TJ Jeep Wrangler. Daily driver or weekend cruising type vehicle. Basically doing the install so it looks factory under the hood. The EGR is my last big decision before it gets things done that can't be reversed without even more expense...
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#2373823 - 09/20/17 09:18 AM Re: No EGR/EGR/Cam Overlap/Detonation, various questions [Re: sycboi]
RTSrunner Offline
super stock

Registered: 11/03/03
Posts: 1173
Loc: Pittsburgh,PA
Sounds cool,that'll be a quick Jeep!

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#2374872 - 09/22/17 12:16 AM Re: No EGR/EGR/Cam Overlap/Detonation, various questions [Re: sycboi]
383man Offline
Too Many Posts

Registered: 01/19/03
Posts: 26405
Loc: Balt. Md
One other thing about the EGR system is they usually are disabled at wide open throttle. They always did that just like if the AC is on the AC clutch is disabled at wide open throttle and so you have max power at wide open throttle. So it wont bother performance at WOT. And at WOT the PCM goes in open loop and runs on the readings from all the sensors but not the 02 sensor. Like most performance PCM's can be programmed for the vehicle to run normal and pass emission's in all modes other then WOT which is open loop and then the PCM can be programmed for max performance at WOT. So you could still enable it for your cruising around if you want since it wont be working at WOT. The PCM will turn it off by the EGR solenoid. Ron
_________________________
My car...63 Sport Fury Max Wedge wanna be street car..with new 493 pump gas full exh eng.......10.76 @ 124.49 ! ! ! My page on the cool 62-65 Mopar site ! http://www.1962to1965mopar.ornocar.com/mmo82008.html

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