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Old 04-30-2008, 07:11 PM   #11
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Quote:
Originally Posted by tjts1 View Post
My point is we shouldn't generalize like the originator of this thread. Modern emissions equipment has come a long way from the 80s and early 90s. Very few spark ignition engines use EGR anymore and most emissions equipment does not hurt fuel economy. Older systems are another story.
So...in such other stories, what might I remove from my 1980 Buick to increase MPG at the possible cost of emissions? It's exempt from emissions requirements in my state. I already intend to sell the cat and possibly remove the EGR.

How about the evaporative emissions system? Does that canister and all those tangled hoses help or hinder FE on a 1980 carbureted v6?
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Old 05-01-2008, 03:53 AM   #12
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I have always been a clean air freak. When I had my 4.7L Dakota, I put a true dual exhaust system on and included the cats.

Currently, I am debating whether upgrading the muffler on my Hybrid Jeep to Flowmaster 50 series will affect air emissions. Any ideas?
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Old 05-01-2008, 05:50 AM   #13
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Mufflers don't treat the exhaust gas, just the noise. AFAIK, it shouldn't affect gaseous emissions except if it acutally reduces the amount of fuel you burn.
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Old 05-01-2008, 06:00 AM   #14
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Originally Posted by theholycow View Post
it shouldn't affect gaseous emissions except if it acutally reduces the amount of fuel you burn.
Which can happen, pretty sure I picked up a couple of mpg going from "generic" mufflers to a Walker SoundFX.
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Old 05-02-2008, 06:13 PM   #15
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Quote:
Originally Posted by theholycow View Post
So...in such other stories, what might I remove from my 1980 Buick to increase MPG at the possible cost of emissions? It's exempt from emissions requirements in my state. I already intend to sell the cat and possibly remove the EGR.

How about the evaporative emissions system? Does that canister and all those tangled hoses help or hinder FE on a 1980 carbureted v6?

leave the evap, it introduces the fuel fumes into the intake, burnign them

take off cat, most likely plugged. remove/block off the vacum line to the EGR(eithe rget the rubber vacum line pluggs, put one on the carb jet and put one on the egr or slip a BB in the vacum line then put it back on
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Old 05-02-2008, 09:05 PM   #16
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Originally Posted by tjts1 View Post
Disabling the EGR improved mileage for me and it was working properly prior to the modification. In 1989 Volvo installed EGR on California cars while 49 state cars didn't have it. The EPA numbers back this up.
I'll add this to my list of things for dyno verification (that's gonna be a very busy day). I'll explain my understanding of this.

The main point behind EGR is to reduce NOx emissions by reducing chamber temperatures, this causes a couple of things to happen in the engine.

First off, less pumping losses. People here P&G because the engine is more efficient when it's working harder mostly because of less pumping losses. I think we can agree on that. You take mostly inert exhaust gases and mix them in with the intake charge and in order to get the same amount of air and fuel in the chamber you'll need to open the throttle more, this will reduce the differential between intake vacuum and atmospheric pressure, therefore reducing pumping losses while giving the same amount of power.

Secondly, it also reduces heat transfer, because convective heat transfer is proportional to the difference in temperature (in this case between gas and walls), and radiative heat transfer is proportional to the difference of the 4th power of the temperatures. Less heat lost to the walls means a greater percentage of the heat is going into increased gas pressure, therefore increased work. Additionally, the inert gases are in there to absorb heat (that's why the overall temp is less) and those gases can expand as well (water injection anyone?). A cooler burn also means the chambers themselves will cool off more and the engine will be less prone to knocking and pinging under load, like driving down the freeway.

I love automotive engineering...

As for the Volvos, California emissions can mean way more than just an EGR on the car. Catalytic converters, all kinds of stuff. Look at the VX with California emissions and without, big difference.
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Old 05-02-2008, 10:27 PM   #17
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Originally Posted by dkjones96 View Post

As for the Volvos, California emissions can mean way more than just an EGR on the car. Catalytic converters, all kinds of stuff. Look at the VX with California emissions and without, big difference.
No, the only difference between California and 49 state cars was the EGR. Both versions of the volvo used the same ECU, engine management and catalytic converter. It just boils down to the EGR. Both the the EPA numbers and my practical experience lead to the conclusion that EGR increased fuel consumption. By 1992 volvo eliminated EGR in this model all together in favor of a new version of Bosch LH. Whats funny is the car passed California smog with lower NOx and HC with the EGR blocked off. Maybe EGR made sense in a laboratory test somewhere, but not in the real world. In other parts of the world Volvo sold the same car with the same engine with a carburetor no catalytic converter all the way up to 1993. US market volvos were always the cleanest versions they produced.
I've heard the whole story about how EGR is supposed to not only reduce NOx as well as improve fuel economy before. I just don't buy it.
Quote:
Originally Posted by theholycow View Post
So...in such other stories, what might I remove from my 1980 Buick to increase MPG at the possible cost of emissions? It's exempt from emissions requirements in my state. I already intend to sell the cat and possibly remove the EGR.

How about the evaporative emissions system? Does that canister and all those tangled hoses help or hinder FE on a 1980 carbureted v6?
If you need to ask, you probably shouldn't be messing around with the emissions controls on your car.
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Old 05-03-2008, 04:57 AM   #18
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Originally Posted by tjts1 View Post
If you need to ask, you probably shouldn't be messing around with the emissions controls on your car.
Not necessarily. This car doesn't get driven, except around the block once in awhile to prevent it from remaining totally stagnant. It's a pretty simple car, carbureted, no ECU, no oxygen sensors, etc. I'll never know if I don't learn, and I intend to learn a lot more than just emissions systems on this car.

I eventually plan to modernize the technology a bit, hopefully with fuel injection. For now, I just want to simplify it so I can learn the basics easier, and do some basic repairs. It's got a bad or warped exhaust manifold and there's a broken pipe and such, so I pretty much have to replace the whole exhaust anyway.
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Old 05-06-2008, 10:26 PM   #19
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This is really because of another post I saw:



The EGR actually won't even increase mileage when disconnected and if it was working properly this will decrease mileage, FYI, but getting a high-flow cat (or none at all) will leave more pollutants in the exhaust and will pollute more than if the car in question leaves it on and suffers a bit of economy loss.

I guess it really depends on what your mods are for, pure MPG or more earth friendly. While you might think those are synonymous, they aren't, and I'm just wondering where people start to say 'This will give me better mileage, but will pollute more'.

I tend to leave my mods to ones that will pollute less and/or the same while increasing mileage. The mods I do to my car most of the time don't even use new parts, they are off junkyard cars so I'm not paying a company to pollute making me a new electric fan assembly when an automaker already has for the used one that might end up thrown away needlessly if I don't use it.
Well another way to look at it is the more MPG's you get the less the delivery truck has to travel to deliver you gas.
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Old 05-07-2008, 03:43 AM   #20
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I keep wondering about EGR... don't seem to have it on my minivan, but have spare intake plenums that have half the kit, and the spare motor I've got seems to have the other half... So when I upgrade to the newer motor and newer intake plenum, I'm gonna have to blank holes off... unless there's a good way of getting EGR to work without having to upgrade the ECU.
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