Egr valves what exactly does it do. I know recirculates exhaust gas I read on one post here. It helps with engine knock. Also helps with timing WHen does it open the most low end, top end, on the highway? Will it give you better gas mileage locally or on the highway? Please school me on egr valves
EGR is used to reduce the combustion temperatures inside the chamber during part throttle cruise speeds. This is to reduce the amount of NOx created. It is an emissions device. Depending on who you ask it may or may not increase mileage due to filling the cylinders with inert gasses rather than a completely fresh air/fuel charge. Again EGR is only activated during part throttle cruise. It's not activated during idle. It's not activated during WOT. If EGR was disabled on a vehicle that originaly came with an EGR system, the timing would have to be retarded, as it would be too advanced causing part throttle ping/detonation. I looked into adding EGR when rebuilding a '70 350. Looking for ways to increase MPG on a brick. I spoke with several knowledgeable people and due to the use of the vehicle(less than once a week) it probably would be negligible to add EGR in that case. On a DD that sees freeway cruising, it might be worth adding, but even then it was debatable on a vehicle that never had it. All agreed that it would reduce the output of NOx at cruise speeds, but the added complexity may not be desirable. Call me a greenie but I plan to maintain EGR function on the Olds I plan on stuffin into my '54. Mostly because NOx is the nasty shit that turns into visible smog/acid rain.
EGR=Exhaust Gas Recirculation It is used to control oxides of nitrogen a component of smog. It is used to dilute the fuel air mixture with inert exhaust to lower combustion temperature which may lessen or prevent detonation "pinging". It is closed at idle and wide open throttle. It is controlled by a temperature sensor or the computer to not operate at cold engine temp. Usually it is hooked by a vacuum hose to a ported signal, one above the throttle plate. Unless it is tuned, by controlling the orifice size, to the engine, it may causes drive-ability stumble. It is often left unhooked or blocked off. It was not used on "traditional" engines.
Stop and think about it for a minute. You can't reduce combustion temps by pumping exhaust into the fuel charge, try holding onto the exhaust with your bare hand. You also cannot increase fuel effeciency or fuel milage by diluting your fuel charge unless you are running extremly rich. Just wanted you to stop and think about what you are saying a minute. If you won a vehicle that runs an EGR valve and it is required to have one make sure you are running the proper one for the vehicle otherwise loose it and properly tune your vehicle.
It's not the temperature of the exhaust gases that reduces the combustion temp. It's the already spent exhaust gases, being inert that causes the reduced temps. If the chamber is partially filled with inert gas(that cannot be re-burned) then the combustion process will not have as much energy to create as high temps and pressure as would normally occur during normal combustion, in turn reducing the amount of NOx produced. This is also true, the spring rates and orifice size do change per application. A valve for a 260 will not work for a larger 455, and vice versa.
What you are saying is that the actually burn will be at a lower temp than it would with a full fuel charge. Now I understand what you are saying.
Ok first thanks for the quick responses. So it might just decrease fuel consumption cause the recirculated exhaust fills the chamber so less volume of fresh fuel is used. Cause better gas miliege in theroy. Ok so the valve isn't open at wot cause there's no vaccum I get that. So at highway speed that would be part throttle and under a load not a big load of course so that's when it would mostly open and I would say in the volume theroy it might get better mpg then I am asking this because I recently replaced a ford 4.6 mod motor with a newer mod motor in my henry J. I was getting 26 mpg highway and now I get 18 mpg.the motor is a stock motor The throttle body is increased and the injectors are bigger 18 lbs to 24 lbs. yes the port are bigger in the heads but the only thing I did was disconnect the egr and turn off the egr in the computer. I'm just wondering if by turning off the egr and removing it That caused me to lose 8 mpg. That is a lot of mpg to lose don't you think? Thanks again for the insite on a egr I will try to put it back togehter and see if that improves mpg
Bingo. Did you also change the intake and exhaust? Just upping the TB/injectors could be contributing to the fuel consumption, combined with the EGR delete. EDIT Were there any other parameters changed? Timing?
No other changes they were both stock motors. The 1996 had small ports. The 2004 motor the factory had the PI heads performance inhanced heads. I did gain hp from 185 to 215 hp but the real only mod was the egr remove
I take it the engine was dyno tuned? I'm not all that familiar with the mod motors, but from what I remember you cannot use the PI heads or intake with the non PI. Well you can but the port flow would be hindered. I'll pass this info on to better persons.
Rite you can put pi heads on a non pi motor but not the other way it increases the compression alittle but I did a motor swap so it was more of an upgrade to a motor with less miles 30,000 from 200,000. Thanks for the help.
I reads somewhere that adding a egr valve to a high compression motor will reduce the octane requirement for the motor,was thinking about trying it with a motor that premium would not cure the ping but found out it was the distributor.
Well from what I have read from this thread the egr valve lowers the temp in the cylinders so it might work on some high compression And the motor I'm talking about is non distributor motor so that's out. But thanx for your input.
Are you running a stock cam? Are you running a catalytic convertor? The stock cam timing is designed to run with backpressure. I had a car drop at least 5 mpg just by removing the cat.
If an older pellet type catalyst was removed improving exhaust flow, velocity and scavenging, then the engine would need to be retuned to compensate for this added flow. Similar to when adding headers to an engine that previously had log type manifolds. An engine that runs lean will have an incomplete burn causing loss of power and mileage. Any changes to an engines volumetric efficiency will require a retune. Elimination of backpressure allows the engine to work more efficiently, less power is wasted on pushing exhaust out, and more on applying it to the crank. Cam timing, and engines in general do NOT use backpressure for anything. Backpressure is the resistance of flow. Cam timing has nothing to do with back pressure. Overlap of the lobes can be changed to improve scavenging for a given operating range.
So why not just displace less air? as in a smaller motor? then you can also have reduced friction also I really dont belive in EGR's myself either
Those "inert gasses" are water and carbon dioxide, so yes, the EGR tries to put out the fire. Increasing gas mileage? I don't buy it. Less energy in the combustion chamber = less power. You'll just open the throttle further to compensate.
Are we talking about performance or lost fuel milage? EGR cools the combustion event without changing the air fuel mixture much. They know you can't screw with the mixture without causing more problems. As far as cams go, there are different grinds for different engine setups. You have blower cams, low compression "pressure builders), turbo, milage, etc.... They all use cam timing to compensate for, or compliment certain engine combinations. With that said, by taking away the backpressure increasing velocity and scavenging you tend to carry some of the charge right out the tailpipe.
Prior to EGR, the intake runners and ports were clean. So were intake valve stems and heads. Spotless. With ERG there is carbon, soot, and crud built up in the intake and on the valve heads and ports. Tell me how this is good.... EGR is a band aid for the emissions crap. I have plugged them off on every OT engine I've had. And still passed the dyno sniffer of the state inspections here. The dyno test here was done at 25 mph with some kinda load so that the engine is loaded. Recently they have discontinued the dyno test and gone back to an idle test. I think not enough failures and retests with the dyno. The idle test rejects a lot more cars.
You need to be careful about that, depending on where you live. If your state has a visual portion of the inspection, the missing equipment could be noticed. Where I am from, that is an instant fail on the test, irrespective of the tailpipe emissions, as is a thrown code, in the case that the EGR valve is electronically controlled.
Both. If an engine is incorrectly tuned it will lack power and mileage will also suffer. Correct. EGR dilutes the mixture but does not affect the A/F ratio as you would if the fuel was just leaned out. True. Cams are designed for a given engine size, breathing, and rpm range. But a cam will not create back pressure, it may not have the correct duration, overlap or lift for a given application, but it will not create back pressure. More likely your area emissions testing does not measure, at least for testing, NOx. Removing the EGR system will increase NOx emissions by double. Removing the EGR system in a city/couty/state that does measure NOx for testing will cause a failure due to high NOx readings.
When did I say a cam will give you backpressure? I give up. I can't even believe I posted on a thread like this in the first place.
No its a stock cam and have never had a cat in the car. Just going to try to put the factory egr back in and see if that improves mpg thanks guys
really? this is fucking lame egr valve talk on the hamb? i hope this shit get closed soon and we get back on topic
Well joe this thread is about the egr valve and if the promotes fuel mileage which is benifical to everybody cause the gas in nyc is up to 480 a gallon.if I drove my car locally. I wouldn't worry about mileage but since I DRIVE my car to places like texas and indiana and illnois.and I will be in wisconsin this year. I would like some fuel economy. I wanted to find out if anybody knows if an egr valve promotes fuel economy thanks everybody for there input on this subject I will update this thread after I re-install the egr valve
hey man thats great more power to you that you DRIVE your car everywhere under the sun.... thats cool! alot of us DRIVE our cars. My point being...... this is the HAMB, your subject is off topic,your motor is off topic, it was said once before in this thread EGR valves were not used on traditional motors. iam sorry for the shittyness some threads on this board get closed for no good reason, then some stay open when they are about as off topic as it can get...... i hope you get your answers and great some great mpg's! by the way what are coming to wisconsin for? shakedown? cheaterama?
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