Hello all,

I've come across a free Edelbrock intake manifold that I would like to put on a 1977 L-82 corvette. The only issue is that it does not have an EGR port. Other posts indicate that deleting the EGR could be a good thing and the only concern would be with emissions. I was wondering if anyone had a similar experience with a situation like this or if there was any way to find out in advance if the car with this new manifold would fail an emissions test? The state would be Delaware.

As always, thanks.

 

Depends on the location. Most State inspection programs require that factory installed emission control devices be present. Some States will not require an emission test after a certain number of years but may still require the device be there. If nothing else an operating EGR will improve your fuel mileage some if that is a concern.

 

Contact the Delaware DMV and ask about their requirements.

 

I removed my EGR when I was still being inspected in FL. Actually, to be honest, the EGR valve had been welded shut by a PO. When I installed a working EGR, my car ran horrible. So, I realized I was going to have to address Nox with a 3-way converter.

So, I installed a 3-way converter that reduced NOX. My understanding is EGR purpose is to reduce unburnt hydrocarbons by recurculating them back into the intake to be combusted. This reduces NOX. The 3-way converter was nice (compared to 2-way) as it reduced NOX using the catalyst.

I was able to pass FL emissions with the 3-way converter and EGR removed. I cannot say you will pass in your state as the levels to pass/fail may differ.

 

The sole purpose of the EGR is to reduce NOx. It accomplishes this by reducing the combustion temps with the inert gas left from combustion. There could be some HC in that from a misfire condition but any HC recirculated would burn and hamper the intent of the EGR. The 3 way Cat is of course a much better way to reduce NOx and it's advent was why some manufactures eliminated the EGR. Some kept it but it's purpose at that point was to satisfy the unconvinced EPA and to increase fuel mileage.

 

I think that is why my EGR valve was welded shut by a PO. It had to be present... working was another story. That's why I added the 3-way cat; it resolved the NOx emissions levels and I didn't have to fix the problem with the car running bad with an (assumed) working EGR valve.

Since then, FL stopped testing, OH did not test while I lived there and AR does not test. I have since gutted the exhaust and emissions systems but I have kept most of the components 'just in case'... save for the exhaust system which is long-gone.

 

You should check to see what the emissions requirements are in your area.

EGR slows down combustion, so the factory's part throttle spark curve advances spark more aggressively to compensate. Simply deleting your EGR valve may make your engine more knock prone unless you limit part throttle spark advance to account for no EGR.

It's true that EGR reduces NOX emissions, however, so does retarding spark. You'll notice a loss of torque and performance but if NOX levels are a concern for an emissions test, you could set your timing to pass the test and then reset the timing back to where the car runs well when you get back home. Retarding spark will also improve HC levels if that is a problem. This can also compensate for a missing/inoperative catalyst.

Many don't realize this but EGR improves fuel economy. By adding EGR at part throttle the driver opens the throttle more to make the same torque as he would if he didn't have EGR. This raises intake manifold pressure, reducing part throttle pumping losses which are significant at the loads the engine operates at during normal cruising conditions. Fuel economy improvements with a properly functioning EGR system are about 2-3%. A small amount to be sure, but a fuel savings nonetheless. At WOT no EGR flows, so it has absolutely no effect on WOT performance. This also tends to be contrary to popular belief. EGR gets a bad rap due to systems that are malfunctioning and the ones trying to diagnose the issues don't understand how it's supposed to work or how to fix it.

But this is a Vette we're talking about! We don't need no stinkin' fuel economy or good emissions!