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Sludgy 10-03-2006 07:15 AM

Managing EGR for MPG
 
I understand why WAI helps fuel economy. Basically, it allows the engine to suck in a smaller mass of air into the engine throught a wider throttle setting. This reduces manifold vacuum, and therefore reduces engine pumping losses.

Another way to achieve the same effect could be by adding exhaust to the intake. First, exhaust is hot, so it would have an WAI effect. Secondly, it would reduce the O2 content of the intake, so less fuel would be added during closed loop operation.

EGR is often used to reduce NOx emissions. Has any Gassaver tested EGR for fuel economy?

MetroMPG 10-03-2006 07:33 AM

I've also read a bit about this in the past month or so. At first glance it makes sense. Something worth looking into.

MetroMPG 10-03-2006 07:53 AM

Understanding exhaust gas recirculation systems

http://www.asashop.org/autoinc/nov97/gas.htm

omgwtfbyobbq 10-03-2006 01:43 PM

The only problem is the octane rating of gasoline, which limits the reduction in pumping losses available from EGR. The nice this is that excessive EGR used with light turbocharging and a fuel with high octane, like methanol or ethanol, results in better efficiencies than diesel engines obtain, with a fraction of the NOx production.

rh77 10-03-2006 02:13 PM

Quote:

Originally Posted by omgwtfbyobbq
The only problem is the octane rating of gasoline, which limits the reduction in pumping losses available from EGR. The nice this is that excessive EGR used with light turbocharging and a fuel with high octane, like methanol or ethanol, results in better efficiencies than diesel engines obtain, with a fraction of the NOx production.

Even worse, North America has very low octane ratings vs. Europe. The average Octane rating is about 87, with 91-92 as the common high-end. There are pumps that offer 94 (Sunoco), and racing fuel pumps at 100, but both of those are expensive, and we don't have Sunocos here. I think they limit the rating because Xylene creates a cancer-causing pollutant when burned.

I think Utah and Colorado limit Octane in parts of the year -- if someone can confirm me on this.

But that's where the problem lies. I recall driving a '03 Ford Fiesta in Scotland that attributed great power and efficiency from its 1.2L engine to a higher compression ratio, as allowed by higher octane.

So then, without the addition of a mild-turbo, would modifying the EGR produce better FE and better emissions if altered in use? The linked article points to a complicated OBD-II computer system that gets the term of "Executive", that controls all of the "air breathin' gadgets".

The term conjures-up those old informational pamphlets, like "EGRs and You: How Does my Car's Emissions System Work???". There's a cartoon of this guy in a suit under the hood, taking reports from the board (EGR, O2 sensor, etc.) and making a decision, "OK, it's settled, we're going to make the air/fuel ratio richer at this point. Any new business? OK...so now what seems to be the trouble in the O2 sensor department...alright, EGR we need you to close slightly..."

For OBD-I or zero, it may be easier to fiddle with, as this complex feedback loop and processor isn't involved so much. May require a piggyback ECU or EIFE to program, if it's worth it.

RH77

omgwtfbyobbq 10-03-2006 02:21 PM

I'd guess it would. The only things the turbo does are improving power in proportion to increased air flow and efficiency by a small bit. For any car it'd probably be easier to scrap the current ECU and run SAFI. In terms of price, methanol seems to vary widely depending on area, but supposedly it can go for ~$2 a barrel, which would make it competative with gasoline, especially when factoring in the increase in efficiency available.

rh77 10-03-2006 02:52 PM

Xylene, but CAREFULLY
 
Quote:

Originally Posted by omgwtfbyobbq
I'd guess it would. The only things the turbo does are improving power in proportion to increased air flow and efficiency by a small bit. For any car it'd probably be easier to scrap the current ECU and run SAFI. In terms of price, methanol seems to vary widely depending on area, but supposedly it can go for ~$2 a barrel, which would make it competative with gasoline, especially when factoring in the increase in efficiency available.

When I had my Evo, the most cost-effective increase in octane was to open a "contractor's" account (free) at the local paint store chain, and buy Xylene by the 5-gallon container. I chose Xylene becuase of its availability, cost, and that oil companies already add it to their fuels to increase octane ratings. Also, if you buy anything else in bulk like Methanol or Acetone, you may get investigated as part of the "Meth-Watch" program as Methamphetamine production is rampant here in the MidWest (it has improved with the behind-the-counter Sudafed law). I'm not making Speed, only driving the car, so I don't have anything to hide. In addition, it was very difficult to find the purity of those other aromatics as Acetone had other distillates added, or you bought it very expensively from a Scientific/Chemistry supply outfit.

Now don't ask about Thanksgiving Day '03 and the "Great Xylene Spill Incident of Shawnee, Kansas" :thumbdown: -- it will "melt" rubber (read: tires, shoes, synthetic broom bristles, garage door seals, etc.) What a mess that was. The only solution was to contain it, blow fans on it, have it evaporate, and keep ignition sources away. Fire containment equipment was readied.

RH77

omgwtfbyobbq 10-03-2006 03:03 PM

Xylene is some nasty stuff. I made the mistake of using it w/o gloves and boy did it itch. Something that someone may want to do is register their car as an alternative fuel vehicle with the state DMV if they have that designation, that way the feds can cross reference that info and hopefully stay off your back. I saw a story on the new behind-the-counter law, and they stated that most meth comes from out of country because it's cheaper to make it and ship it. Honestly, even if they suspect you of using it for illegal pruposes, the most they may do is have a heli buzz your place every now and then. My mom used to put up shade cloth for our dogs during the summer, and the police heli would buzz us once or twice a month, because dogs are weed. :rolleyes:

rh77 10-03-2006 03:11 PM

OK I have to ask
 
Quote:

Originally Posted by omgwtfbyobbq
Xylene is some nasty stuff. I made the mistake of using it w/o gloves and boy did it itch. Something that someone may want to do is register their car as an alternative fuel vehicle with the state DMV if they have that designation, that way the feds can cross reference that info and hopefully stay off your back. I saw a story on the new behind-the-counter law, and they stated that most meth comes from out of country because it's cheaper to make it and ship it. Honestly, even if they suspect you of using it for illegal pruposes, the most they may do is have a heli buzz your place every now and then. My mom used to put up shade cloth for our dogs during the summer, and the police heli would buzz us once or twice a month, because dogs are weed. :rolleyes:

Alright I have to ask -- and it will lead somewhere, I promise. What does your Username stand for: Oh my God, What the F---, Bring Your Own Bar-B-Que? Judging by that, I would guess your location to be: Memphis, the Carolinas, Texas, or KC. Or I could completely be wrong. I'd fail miserable as a detective (except for the hot pursuits -- insert Roscoe P. Coltrane chuckle here).

RH77

omgwtfbyobbq 10-03-2006 03:24 PM

You are right about the acronym, but even if the character count would allow it, it would still be in letter form. And you are wrong about location, but that's not reason not to guess. We've gotta be wrong to figure out what's right! :D


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