Does emissions equipment hurt gas mileage?

Just my opinion....the initial pollution control devices made cars that didnt run well and didnt get good mileage at all. Now we can get good mileage and good power out of engines that are heavily modified to control emissions.

If you want to go back to the carburetor and distributor setups and take off all emission controls, I think you will still get poor power and poor mileage.

Seems to me the only real "equipment" is the EGR and cat. Early EGR's weren't too good, but if you look at EGR in wikipedia the suggestion is that modern EGR's get more out of the gas than they cost. So I think you're right.

--Vic

It's less 'emissions controls' and more 'engine management' these days. The early days were ways to try and keep smog down, now it's more about burning fuel more efficiently.

Vic Smith wrote in news: snipped-for-privacy@4ax.com:

If you could have a modern eng optimised for no emision equip.then it would get better milage. if you just took the emision equip. off a preexisting eng.then it wouldn`t get as good. So your kinda both right and wrong. KB

Jesse wrote in news:538e83b7-4897-4121-b1ad-e22da5ec99d8 @v23g2000pro.googlegroups.com:

Engine control these days is all about the cat (God save the cat!). The mixture is "accurate" for the cat, and also for reducing the Holy Trinity of HC, CO and NO. It is not necessarily "accurate" for other considerations. This can mean a mixture that is richer than it otherwise might be, and thus lower mileage.

I believe you could get better mileage in modern cars at cruise if the mixture were allowed to run leaner than it currently is during cruise. Mileage is enhanced by extended driving at light-throttle cruise. Light- throttle cruise, however, also elevates NO emissions. To correct that, either the mixture is enriched and the timing retarded, or an EGR system feeds inert gases into the combustion chamber, wasting some of the cylinders' effective volume. Both of these will reduce gas mileage.

I also believe that the engineers have mastered the art of engine control to the point where they have achieved /significant/ gains in fuel efficiency during cold operation, acceleration and deceleration, and at idle. These gains possibly more than offset any mileage lost due to cruise enrichment, volumetric efficiency loss or other emissions-related changes.

I've so far ignored computerization, which is at the heart of the modern engine. Other industries, bidden only by the profit motive and not by government edict, have computerized very heavily since 1981, to the great benefit of them and their customers. There's no way of telling now, but I suspect engine controls would have eventually been computerized even in the total absence of any emissions controls at all. And with computerization would have necessarily come cleaner, more efficient engines. Maybe not /quite/ as clean as we have now, but likely significantly less expensive ones, and ones with possibly better gas mileage.

Could you get back the large cost of mandated emissions controls through any resulting better gas mileage? I'm not sure. There must be a reason some poorer parts of the world until very recently still had non-feedback FI and carburetors.

But hey, why post here? Ask Tom and Ray (AKA "Click and Clack, the Tappet Brothers"). Your question is right up their alley, and I've not yet seen anyone else ask it.

Comments inserted...

Like some have mentioned, cars now are a whole 'package', and dont have alot of emissions control equipment tacked on like they used to. The days of heavily plumbed egr and air injection, spark controls and heat risers are over.

That is an understatement! EGR reduces NOX, and early systems were incredibly problematic, sometimes causing massive hesitations, power loss and poor mileage. If it was disconnected, many cars would detonate fiercely. I made alot of money off of those crappy systems...

Very true. One of the last frontiers of effeciency improvements is reduction of pumping losses, the work wasted by the engine pulling against a vacuum on the intake stroke. Since the early '80's, engineers have used egr as a way to increase throttle openings at cruise to reduce pumping losses by diluting the intake charge with exhaust gas as well as to control NOX.

Bottom line IMHO; your father was right in 1976, you are right now. HTH, Ben

Modern cars don't have any "emissions equipment." They have tightly designed engine systems that are designed as a unit.

Cars back in the seventies had "emissions equipment" that was tacked on to solve issues like the fact that the engines weren't burning very efficiently. Modern engines are designed to burn efficiently in the first place, and they have closed-loop control systems to make them do that. The control systems aren't "emissions equipment" at all.

There are some things on modern cars, like catalytic converters, which might reduce fuel economy slightly. And it's possible that if you went into the ECU code and decided to optimize it for best economy rather than good emissions performance you might be able to get a little more mileage out. But this isn't being done by "removing emissions equipment."

--scott

Thanks for the responses. Very informative. I'll have to remember all of this for next time I see my father in law.

The whole system is "emissions equipment" nowadays, I think. Everything is too integrated to be able to separate a few parts and call it "de-smogging".

Go back to the era when carburetors, mechanical distributors, etc were in vigor and I dont think you will get either decreased emissions nor good fuel economy.

If you could design an engine from the ground up, optimum compression ratio, cam, air-fuel and ignition timing curves, then yes, you could get better mileage. But this would mean disregarding emissions performance (NOx in particular, since that places an upper limit on combustion pressures).

Ripping the emission control h/w off of an existing car won't buy you much. It might drive the ECU into some 'limp home' mode and actually cost you performance and fuel.

The very large engines being put into cars are much more of a milage hit than the emission controls.

Do we really need 0-60 times in the 7 second range rather than 9-10 seconds? The result of the monster engines is the operation during normal driving at very low throttle and effective CR, really hurting gas milage.

Hey, I am as much a gearhead as anyone, and love high performance cars. I bought an old vintage race car to run in vintage events and get my thrills on the track instead of the highway. I gave up my Dodge R/T and got a Prius.

I don't know the answer but if you look at this chart:

you can see that the mileage for a 1983 Ford Ranger was as high as 41 mpg and for 2008 it's only 26. What does that tell us? It tells me that they used to get better gas mileage. They also probably used to have much higher emissions. My 1999 Ranger with a 3.0L auto has almost no emissions for NO and HC. Probably pollutes just a little more than an electric car (well, there is some CO2 also). To me it looks like I'm trading 15 mpg for cleaner air.

I had a 1966 Mustang with a 289 ci V8 and a 3-speed auto trans. I got about

23 mpg and my foot was usually on the floor. I don't know how much a comparable Mustang gets these days but I'd guess it's less.

We must have huge engines, because we all want huge and heavy car bodies to compensate for our small penises. Therefore enormous engines are required in order to accelerate to highway speed in any reasonable time.

Sure, but you probably don't have a penile inferiority complex like so many other drivers do.

--scott

I bet a nickel that the mass of the 1983 Ranger is a whole lot less than that of the 2008. That's the real problem.

--scott

Also the EPA changed the way they measure fuel economy. Some vehicles were rated at as much as 1/3 less mileage under the new standards. That alone would account for almost all the difference. I seriously doubt that an automatic was rated at

41 mpg back in '83.

-jim

My brand new 66 Mustang 289 225 hp got as good as the newer Sonoma

140 cid but it had twice the engine size.

Size is not everything, clearly.

Not all "emissions systems" are created equal.

EGR, for instance, hurts efficiency all by itself, but then auto manufacturers discovered that they could use it as a way to control detonation without retarding timing (it slows combustion not unlike water injection). So a handicap got turned into an advantage.

Air injection pumps, which are rarely ever used any longer, were just a parasitic draw on the engine and never helped efficiency.

PCV slightly hurts efficiency by enforcing a minimum airflow through the engine, making it hard to do other things like idle very slowly and/or shut down cylinders at idle without resulting in an over-lean mixture. But PCV makes engines last a lot longer because it really cuts back on gunk building up in the crankcase, acids in the oil, etc.

On the whole, I'd say that the auto makers have managed to adapt most emission controls to the point that they are at worst a break-even.

So you think that a guy with a Charger R/T is "compensating for something" *more* than the guy with a Miata, SLK, Lexus IS, Acura NSX, or 370Z?

I, for one, am much more likely to think the Miata/SLK/IS/NSX/370Z guy is the one stuffing his shorts, spending hours in the gym (near the mirror, of course), using corny lines at singles bars, and answering all the male enhancement SPAM.

:-)

The guy with the Charger is happily married, getting plenty, and just wants to carve a few corners AFTER he drops the kids off at school.

Yep. At a recent car club event, we had the opportunity to run a few vehicles across a commercial truck scale. The results were interesting- my '69 big-block R/T weighed 4050 pounds- about what I thought. A circa

2000 Ford Ranger v6 weighed 4200 lb- about 1200lb more than I would think a "compact" pickup should.