SuperRA

From all that I think that it does, it will disable EGR. Anyone done this?

87 Renix

DFlintstone

You might look at the forum rules. I guess they frown on talking about disabling smog stuff. Even that stupid, worthless deal. I think my Jeep might work just fine if mine was hooked up.

Radi

Odd as it sounds, on certain vehicles removing the EGR actually hurts performance.
You have a knock sensor. The EGR cools and slows combustion, reducing detonation. That allows the ECU to run more timing advance, which helps performance and economy.

1970's EGR's were awful, lol. They really did need to hit the trashcan. By mid 80's they were pretty harmless, provided they are kept clean and in good repair. If it's malfunctioning it'll cause issues.

Mendax13

also they cool cylinder temps to reduce Nox. exciting stuff

DFlintstone

Well now THAT IS interesting. Being that I done got "learned" in the 70's and have a knock sensor. (my smog instructor said to be careful not to put a ball bearing in the line to the EGR valve, as nobody will see it and it won't work that way). In 77 or so.

I've been keeping good records, maybe I'll put that advise to test....I've never heard it knock though. Actually feels just a tad retarded. If I could I'd crank the dizzy a few degrees. I do plan to do the advanced CPS mod when I have the time. (that would be just for Renix Jeeps with the knock sensor, I think)

wildbill1

The EGR, if it's working correctly, will lower combustion chamber temperatures. It will decrease the likelihood of detonation (knock) and will increase fuel economy. It is not necessarily a bad thing and you should not eliminate it if it's working.

Emmisions control devices got a bad name in the early days. There have been big improvements since then.

SuperRA

I think I remember 5-90 mentioning that his jeeps ran better and produced less emissions when the EGR wasn't functioning. If that's the case, then no need to have carbon depositing gas running through the intake. I already cleaned it all out once, I don't want to be doing it on a regular basis..

cruiser54

Once in how many miles? I've never had one fail. Please remember the forum rules.....

highmileage

If I recall the EGR doesn't just affect timing but also the IAT, also it may cause a run rich situation burning up your cat as well.

5-90

On a low-compression engine, the EGR does pretty much squat.

When I got my 87 some years ago, it passed smog fine. EXCEPT the EGR had failed - and they only found that by testing manually (after I'd told them the ONLY thing they're allowed to do is clip the timing lead on. Dammit, why does no-one listen?) NOx was acceptable, HC and CO were both low.

I put on a new EGR (I wasn't about to let them work on the engine. As far as I'm concerned, every Smog Test shop is a "Test Only" shop...) and took Clyde back in for a retest.

NOx was unchanged. HC and CO were firewalled - dude tried to sell me on a cat, but it passed.

The theory of the EGR is relatively sound, reduction of NOx by dampening combustion temperatures. But, there are several better ways to do the job, none of which involve crapping up the intake with carbon.

And, the compression of the AMC six isn't high enough for the presence or absence of the EGR to matter worth a fart in a firestorm, but we're stuck with it because it's an "OEM Emissions Control device."

No matter how pointless and stupid.

(SCR=8.7:1, DCR is something like 6.5:1)

I would like to see the restriction on emissions alterations lifted, and then a "sliding scale" discount (relative to emissions output levels) on registration after smog checks. We could save money AND the environment (and paying more when you pass? Chuffed to little mintballs about that I am not.)

As I have said over and over - it is not the idea of emissions control that I find so bothersome. Reducing tailpipe emissions also (generally) means increased combustion efficiency, which means increased fuel economy. It is the execution of the programme I find sorely lacking...

In answer to your "What If?" question - disconnecting the EGR solenoid will disable the EGR valve from functioning, it will not open and trickle exhaust gas back into the intake stream. Based on my experience with failed parts, this does not cause any hindrance to performance with the RENIX-controlled AMC six.

DFlintstone

Static Compression Ratio, Dynamic Compression Ratio? Interesting idea. (the) "Gulp" .

"Physics" , might be a mathematical description of the real world. Guess DCR might relate to to breathing, or porting.

5-90

SCR - Static Compression Ratio, based on part geometry, not accounting for cam dynamics. Ratio between BDC and TDC volume.

DCR - Dynamic Compression Ratio. Based on part geometry, taking into account cam timing. Ratio between IVC volume and TDC volume

DCR will always be lower than SCR, and may be changed simply by changing the camshaft. Changing the SCR usually requires machine work.

IVC - Intake Valve Closing. Expressed in camshaft degrees, the piston is likely on its way back up when the valve closes (in an effort to take advantage of inertial supercharging,) which means that the DCR base volume is going to be less than the SCR base volume.