EGR Question

[sturgillbd]

I notice a few of the guys on here disabling EGR on their swaps. It seems counter-productive to do this because it lowers combustion temps and will allow a little more compression ratio without detonation. can anyone chime in?

[RobertISaar]

people do it for many various reasons(some of which don't make sense).... i find it beneficial, so i only disable it when it would otherwise interfere with getting my base fuel and spark calibration nailed down, then it goes back on.

[EagleMark]

Many times it is disabled for performance engine builds or engine transplants to hot rods which do not require them etc... there's no reason to turn it off on a stock engine, no benefit, actually less fuel mileage along with higher emissions.

[Fast355]

Many times it is disabled for performance engine builds or engine transplants to hot rods which do not require them etc... there's no reason to turn it off on a stock engine, no benefit, actually less fuel mileage along with higher emissions.

I am not a huge fan of EGR. Too much carbon gets thrown back into the intake to choke the intake and heads. Combined with the PCV fumes it makes a nasty mess of sludge.

I disable the EGR and remove it whenever possible, especially when it cannot be tuned correctly. Like my 0411 run Express. It has the EGR come on at all the wrong times and does not use much EGR when it would help provide fuel economy benifits. Basically it cranks up the EGR under part-throttle acceleration, causing a stutter or bog and then doesn't do much at cruise.

[steveo]

it's an emissions thing, it doesn't do anything beneficial. there are NO power gains from an EGR.

it's pumping an inert gas into your intake, so you have less room for oxygen and fuel.

yes it lowers combustion temperatures and reduces detonation, but all that does is allow you to advance timing and get enough power to overcome most of the losses.

if you remove it and remove that timing advance as well, you're back where you started, or better

on a stock engine though? no reason to take it off

cams with more overlap tend to create an egr effect through polluting the intake manifold anyway... look at the LT4, it never had an EGR from the factory, and met emissions just due to cam design

[sturgillbd]

Thanks for the input fellas. I am still debating the use of egr. I am still working on the body and other issues on my jeep build. I originally planned on using the 8746 ecm but have now acquired some 7427's and have built the harness for it. The engine/transmission is in the frame and I have had the harness connected to all the sensors. Tunerpro can read tps, cts and even the map once I twisted the distributor and gave it a few reference pulses. The engine is a '96 up vortec 5.7 and I bought one of the cheapy sealed power cs808 cams. Heads are swirlports off a 92 5.7 Heads cc'd about 65 with a syringe and mineral spirits. Compression should be upper 8's or low 9's. Like I said, this is going in an old jeep so it doesn't need much horsepower to be dangerous. I do have the 2PR vss from JTR. What are your thoughts on using EGR on this setup? I will be starting the engine in the next couple of weeks when I get the fuel lines plumbed in and get my regulator mounted on the firewall. I have basically disabled the regulator in the TBI unit and going to regulate the fuel pressure via a Mallory 4307 pressure regulator. Another question is: Would it be a good idea to use the vacuum reference on this regulator to help with PE or would it be best to let the ECM handle the PE?

For any who are interested, here are some older pics taken at first of the summer when we first set the body back on the frame to see how everything aligned up after replacing floorpans etc..