Vortec Intake Manifold with EGR

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Vortec Intake Manifold with EGR

Post by 77mali on Mon Nov 03, 2014 7:15 pm

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!)
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Re: Vortec Intake Manifold with EGR

Post by jerry46765 on Tue Nov 04, 2014 2:09 am

OK I'll bite, when does EGR boost fuel mileage, cold weather running?
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Re: Vortec Intake Manifold with EGR

Post by 77mali on Tue Nov 04, 2014 7:34 am

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.
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Re: Vortec Intake Manifold with EGR

Post by dynchel on Tue Nov 04, 2014 8:01 am

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.
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Re: Vortec Intake Manifold with EGR

Post by 77mali on Tue Nov 04, 2014 8:41 am

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.
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Re: Vortec Intake Manifold with EGR

Post by dynchel on Tue Nov 04, 2014 8:48 am

I forgot you have state inspections.
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Re: Vortec Intake Manifold with EGR

Post by ant7377 on Tue Nov 04, 2014 10:39 pm

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 Smile 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.
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Re: Vortec Intake Manifold with EGR

Post by bigredlaguna on Wed Nov 05, 2014 12:18 am

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.
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Re: Vortec Intake Manifold with EGR

Post by 77mali on Wed Nov 05, 2014 7:15 pm

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.
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Re: Vortec Intake Manifold with EGR

Post by jerry46765 on Wed Nov 05, 2014 7:18 pm

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 -
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Re: Vortec Intake Manifold with EGR

Post by 77mali on Wed Nov 05, 2014 7:20 pm

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 Smile  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.
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Re: Vortec Intake Manifold with EGR

Post by ant7377 on Wed Nov 05, 2014 7:33 pm

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.
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Re: Vortec Intake Manifold with EGR

Post by 77mali on Wed Nov 05, 2014 8:44 pm

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.
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Re: Vortec Intake Manifold with EGR

Post by bigredlaguna on Thu Nov 06, 2014 12:19 am

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.
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Re: Vortec Intake Manifold with EGR

Post by ant7377 on Thu Nov 06, 2014 7:00 am

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.
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