Vortec Intake Manifold with EGR
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G3GM :: G3 Tech :: Engine & Driveline
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Vortec Intake Manifold with EGR
I'm posting this for anyone considering doing a Vortec upgrade to their top end with new cylinder heads and intake manifold.
Edelbrock no longer makes a Vortec intake with EGR (this has been the case for a while now). When I built my motor I was recommended the Edelbrock Performer 2116- good choice but no EGR. If you want to keep EGR for increased MPG, they are avail from Chevy/GM Part# 12496820(About $150 more than the Performer 2116).
http://www.crateenginedepot.com/Manifold-Vortec-Design-Aluminum-12496820-P9891C576.aspx
Better pics @ Summitt
http://www.summitracing.com/parts/NAL-12496820/
OEM Bolts:
http://www.crateenginedepot.com/Bolt-Special-Intake-manifold-bolts-12550027-P10081.aspx
Also, use the Felpro #1255 gaskets. They are extra thick (1/8"). They do not work like the original OEM style gaskets are very thin and have the slightly raised red compression gasket on them (that are easily over torqued!)
Edelbrock no longer makes a Vortec intake with EGR (this has been the case for a while now). When I built my motor I was recommended the Edelbrock Performer 2116- good choice but no EGR. If you want to keep EGR for increased MPG, they are avail from Chevy/GM Part# 12496820(About $150 more than the Performer 2116).
http://www.crateenginedepot.com/Manifold-Vortec-Design-Aluminum-12496820-P9891C576.aspx
Better pics @ Summitt
http://www.summitracing.com/parts/NAL-12496820/
OEM Bolts:
http://www.crateenginedepot.com/Bolt-Special-Intake-manifold-bolts-12550027-P10081.aspx
Also, use the Felpro #1255 gaskets. They are extra thick (1/8"). They do not work like the original OEM style gaskets are very thin and have the slightly raised red compression gasket on them (that are easily over torqued!)
77mali- Donating Member
- Street Cred : 62
Re: Vortec Intake Manifold with EGR
OK I'll bite, when does EGR boost fuel mileage, cold weather running?
jerry46765- Donating Member
- Street Cred : 20
Re: Vortec Intake Manifold with EGR
The EGR valve opens when it encounters back pressure from the car's exhaust and channels it back into the combustion chamber. It will make the fuel warmer and warm fuel heats up more efficiently. In a well tuned engine this should produce an increase in miles per gallon. How many or what percentage? I don't know how it's calculated but have always heard that EGR helps MPG.
I had forgotten but also, in my state the inspection stations are supposed to check if your car originally came with such items from the factory. The emissions targeted by EGR come from nitrous oxides that are produced at very high temperatures. By mixing the car's exhaust with the intake air, the amount of oxygen in the mixture is reduced and its combustibility is also decreased, which allows the air/fuel mix to burn at lower temps than without EGR.
I had forgotten but also, in my state the inspection stations are supposed to check if your car originally came with such items from the factory. The emissions targeted by EGR come from nitrous oxides that are produced at very high temperatures. By mixing the car's exhaust with the intake air, the amount of oxygen in the mixture is reduced and its combustibility is also decreased, which allows the air/fuel mix to burn at lower temps than without EGR.
77mali- Donating Member
- Street Cred : 62
Re: Vortec Intake Manifold with EGR
Do they actually smog check a '77 model year car in your state? In Ohio you are exempt after 25 years, G body's & first gen S10's are now fair game for non emmisions SBC swaps.
dynchel- Donating Member
- Street Cred : 40
Re: Vortec Intake Manifold with EGR
We have an exemption for cars over 15, I believe but they are supposed to check what it should have come with specific to model year (IE- EGR, CATS). If they don't see the proper equipment then they can in theory reject it.
77mali- Donating Member
- Street Cred : 62
Re: Vortec Intake Manifold with EGR
I forgot you have state inspections.
dynchel- Donating Member
- Street Cred : 40
Re: Vortec Intake Manifold with EGR
77mali wrote:We have an exemption for cars over 15, I believe but they are supposed to check what it should have come with specific to model year (IE- EGR, CATS). If they don't see the proper equipment then they can in theory reject it.
Paul, we have the same thing here but the guys checking dont really know what they are looking for anyhow. Most are too young to know what it looks like and then you have friends that take care of you with stuff like that. Im thinking of hooking it back up on the 73 though to see if it stinks less after I put it in the garage after driving it. That damn car stinks like crazy cant figure it out. Im going to put the little crossover block off plates on the intake gaskets over the winter. Just didnt want to take it apart now.
ant7377- G3GM Addict
- Street Cred : 36
Re: Vortec Intake Manifold with EGR
The only thing EGR is for, is to reduce NOX emissions. The exhaust gasses are inert and do not contribute to the combustion process, thus lowering combustion temperatures which create NOX. EGR isn't open all the time, just under light load or light acceleration, and is controlled by a vacuum signal on this generation of vehicle.
Potential fuel savings are probably due to the displacement of oxygen because of the introduction of the inert exhaust gas, requiring less fuel as compared to a non-EGR engine.
Potential fuel savings are probably due to the displacement of oxygen because of the introduction of the inert exhaust gas, requiring less fuel as compared to a non-EGR engine.
bigredlaguna- G3GM Senior Member
- Street Cred : 53
Re: Vortec Intake Manifold with EGR
bigredlaguna wrote:The only thing EGR is for, is to reduce NOX emissions. The exhaust gasses are inert and do not contribute to the combustion process, thus lowering combustion temperatures which create NOX. EGR isn't open all the time, just under light load or light acceleration, and is controlled by a vacuum signal on this generation of vehicle.
Potential fuel savings are probably due to the displacement of oxygen because of the introduction of the inert exhaust gas, requiring less fuel as compared to a non-EGR engine.
If that's the case then EGR would be beneficial if you did a lot of short trips. What happens at highway speeds for instance? Does the valve just close and there are no inert gases in the mix? My truck has EGR with fuel injection- I'm getting close to 20mpg with my little 305.
77mali- Donating Member
- Street Cred : 62
Re: Vortec Intake Manifold with EGR
If you have to run EGR to pass some state emissions test, so be it.
Once again I have to ask, what do you want, fuel economy or performance? Dumping hot exhaust back in the intake may improve emissions, but it will NOT increase performance. And with a vacuum controlled EGR, I see no benefit for increase MPG other than during cold weather warmup.
thanks -
Once again I have to ask, what do you want, fuel economy or performance? Dumping hot exhaust back in the intake may improve emissions, but it will NOT increase performance. And with a vacuum controlled EGR, I see no benefit for increase MPG other than during cold weather warmup.
thanks -
jerry46765- Donating Member
- Street Cred : 20
Re: Vortec Intake Manifold with EGR
ant7377 wrote:77mali wrote:We have an exemption for cars over 15, I believe but they are supposed to check what it should have come with specific to model year (IE- EGR, CATS). If they don't see the proper equipment then they can in theory reject it.
Paul, we have the same thing here but the guys checking dont really know what they are looking for anyhow. Most are too young to know what it looks like and then you have friends that take care of you with stuff like that. Im thinking of hooking it back up on the 73 though to see if it stinks less after I put it in the garage after driving it. That damn car stinks like crazy cant figure it out. Im going to put the little crossover block off plates on the intake gaskets over the winter. Just didnt want to take it apart now.
Have you checked for critters anywhere in the engine bay or elsewhere? Is that the kind of stink or is it chemical? I've got to check my truck too- it smells when the heat is on now. I've got to see if I have a cabin filter.
77mali- Donating Member
- Street Cred : 62
Re: Vortec Intake Manifold with EGR
No not organic. Smells like carb is rich (it isnt). I cant figure it out . I think its kinda like fuel is boiling in the carb. I put a heat sheild under the carb. Didnt really help much. Someone said put the little sheilds on the intake gaskets. Im going to try it.
ant7377- G3GM Addict
- Street Cred : 36
Re: Vortec Intake Manifold with EGR
The 73 has a crossover style manifold right?
The part that's underneath it is removeable so you can clean it out. Sometimes the gaskets themselves will degrade over time and could be leaking a small amount of coolant or oil. I had so much crap in the old manifold, mostly carbon build up, I had to lightly chisel it off the crossover openings. It was disgusting.
The part that's underneath it is removeable so you can clean it out. Sometimes the gaskets themselves will degrade over time and could be leaking a small amount of coolant or oil. I had so much crap in the old manifold, mostly carbon build up, I had to lightly chisel it off the crossover openings. It was disgusting.
77mali- Donating Member
- Street Cred : 62
Re: Vortec Intake Manifold with EGR
77mali wrote:bigredlaguna wrote:The only thing EGR is for, is to reduce NOX emissions. The exhaust gasses are inert and do not contribute to the combustion process, thus lowering combustion temperatures which create NOX. EGR isn't open all the time, just under light load or light acceleration, and is controlled by a vacuum signal on this generation of vehicle.
Potential fuel savings are probably due to the displacement of oxygen because of the introduction of the inert exhaust gas, requiring less fuel as compared to a non-EGR engine.
If that's the case then EGR would be beneficial if you did a lot of short trips. What happens at highway speeds for instance? Does the valve just close and there are no inert gases in the mix? My truck has EGR with fuel injection- I'm getting close to 20mpg with my little 305.
This is stuff I learned in high school shop class, so I'm a bit fuzzy on the specifics of operation, but I do remember that NOX is created in the combustion process when the temperature meets or exceeds a certain temperature. EGR is the only way to keep the combustion temp under control, and to date every vehicle sold in the USA has an EGR system to perform this task. There is no reason to do this from an engine performance standpoint. Even for economy it doesn't make sense to do this. The hotter the combustion process is, the more powerful it is. More powerful combustion=less throttle for the desired power level as compared to an identical engine with EGR added. Less throttle=less fuel used.
As far as highway driving, the EGR can be open. An improperly calibrated EGR valve can let too much gas through and cause the engine to misfire. One of my first cars did this, (77 Firebird, Olds 350, Q-jet) and the mechanic I took it to ended up putting a BB in the vacuum line to disable the EGR valve after other tuning efforts failed to fix it.
I think the key to your 305 getting 20 mpg is the fuel injection and the computer controlling it being able to trim the fuel curve and timing more accurately than a carburetor and distributor can.
bigredlaguna- G3GM Senior Member
- Street Cred : 53
Re: Vortec Intake Manifold with EGR
77mali wrote:The 73 has a crossover style manifold right?
The part that's underneath it is removeable so you can clean it out. Sometimes the gaskets themselves will degrade over time and could be leaking a small amount of coolant or oil. I had so much crap in the old manifold, mostly carbon build up, I had to lightly chisel it off the crossover openings. It was disgusting.
The port was all clogged up like that when i took off the intake to paint it . Had to clean it out with a dremel tool. Ill get around to it one the long crappy days of winter are here.
ant7377- G3GM Addict
- Street Cred : 36
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