MPG and the Introduction of EFI

You are not the only one who has seen that same correlation between fuel injection and carburetors. Or that between non emissions compliant carburetors and engines Vs the emissions tuned ones as well.

Some years ago I changed engines in my old 1985 F150 from the stock emissions compliant 5.9 L V8 to a custom built 460 (7.6 l) with a aftermarket everything and saw a near doubling of horsepower and fuel mileage at the same time. It still makes me wonder where all that fuel was going in the 5.9 L.

The automotive "engineering experts" will say people like us are wrong and toss a trunk load of mathematical nonsense to show they are right and occasionally lump us in with the HHO crackpots but a few million old school gear heads who learned their trade from hands on aplication will argue otherwise because experience gave them similar reasons to question the validity of the modern stuff as well!

Check out the off road forums to find out what the real hands on modern day gear heads think about emissions compliance and its less than dismal effects on what engines can do in regards to real power and fuel mileage. There is a reason they strip every emissions related component off of their engines and use aftermarket off road rated parts and engine setups.

I still say that fuel is wasted to feed the catalytic converter. Emissions is such a big thing with the regulators. They don't care if we have to buy more fuel, they just want good numbers.

If a catalytic converter doesn't get enough fuel, it cools off. If it cools off, it can't burn fuel. So they feed it with the computer to keep it hot.

A well tuned engine probably doesn't waste much fuel. The regulators have to engineer for the people who don't tune engines, change oil regularly, and watch tire pressure. Everybody has enough money for gas, so they solve the problem that they see.

I am one of those hands on gear heads, you know one of those guys that could adjust a 4bbl carb with a vacuum gauge. I owned a 1975 Jeep wagoneer with a 401 cu engine, this thing had electronic ignition some kind of computer running everything and about 8 to 1 compression, well the engine wore out and the computer went bad, well that computer cost $300.00 well I pulled the engine and rebuilt it, I raised the compression to 9.5 to 1 took out the computer and threw it away, took out the motorcraft 4bbl and threw it as far as I could and removed the electronic distributor.

I replaced the carb (with the help of a home made adaptor plate) with a quadrajet, the distributor was replaced with a Mallory duel point distributor and had it align bored and raised the compression. I had hardened seats pit in the heads as leaded gas was hard to find by then and replaced the cam with an after market one by crane it moved the power toward more torque as I lived in Utah and did allot of trailer hauling with it and bored out the holes .020 installed new pistons, I raised the compression by having the deck and the heads.

Prior to all of this I was getting 10 mpg and was barely passing emissions, the rules there were that you were not to modify your engine at all, well when I got it all together and broken in it was time to get it emissed, I didn't tell them about the work I had done and let them hook it up, this engine sans all that junk got superior emission results so much so that the technician thought that his machine was not working properly. Before this I always sweat ed these things as we never could buy new cars and they barely passed, my mileage went up to 22mpg.

This is the truth and those engineers cannot explain this so I will believe them, I believe that this crap is just to make someone money and some special people to justify their positions.

Also my father had a Buick Electra with a 400 series engine in the 60's that got 20mpg and that thing weighed almost 4,000 lbs, so maybe we are depending too much on technology and need to take a step back, Oh fiel injection is not new, air craft were fuel injected in WWII so that they could operate at altitude and certain drag racers used it to get more gas into the cylinders, why are we trying to use this to get better mileage. Hey I just thought of something if cars are lighter now and getting the same mileage as the heavy ones doesn't that mean that they are getting worse mileage?????

Michael..

I don't drive any more, but back in the days...

At one point in time, I had two VW Square-backs, both 1969 vintage, both purchased used. One had originally come from Mexico or Brazil, and was fitted with a conventional carburetor. The other was fitted with fuel injection. After finding a mechanic that really understood fine-tuning these engines (he raced VW's as a hobby), both got pretty much the same gas mileage- something like 39 gpm highway. Later, I had a '72, same model, I believe a slightly larger engine, but with smog control. Never got over about 25 mpg. But I had changed mechanics, and I never was as good as he was at it (and he had some pretty sophisticated equipment for back in those days). Later, I went to an MG Midget- about the same size engine, single carb. I could tune that one- back to 39 mpg on the highway (after I "lost" the catalytic converter on a speed bump).

My personal experiences are, of course, limited, and may have no bearing on the results the rest of the world might enjoy. But I am convinced that engines are detuned to accommodate the emissions regulations. Now, how is someone using 39 gpm on the highway doing more damage to the environment than someone using 18 mpg? Something is very wrong with this picture...

I had a 1984 Honda accord which got 40 mpg... a new one is rated at 26+/-...

These sort of fuel efficiency claims are always highly personal, subjective and perhaps prone to error. For example are you sure your odometer has accurate (how do you know), was your fuel gauge accurate, was your driving typical had you been drinking heavily?

It's hard to believe that the un-aerodynamic and heavy cars of yesteryear with their large crude engines were actually better than todays efforts.

The only way to settle this sort of argument is to actually do some tests or check test results from a reliable source (car companies don't qualify).

It's a bit like old timers describing the "good old days" when fruit was sweeter, music was better and (insert appropriate gender) the girls were prettier.

Two words: Emission controll. At near or full open throttle there is little difference between the two systems in as far as power goes.

Very few vehicles operate in this envelope, spending most of their lives at closed or part open throttle.

Remember when the exhaust emission regs first became evident, and we were running carbs, and we had all of that power sucking tube plumbing all over the engine bay? Air injection pumps etc?

Well, EFI has allowed the doing-away with all of that, and we can now meet very stringent regs like CARB, and EurolV etc and enjoy 'performance'.

Plus refined valve timing etc.

If you use horses you have to feed 'em. Personally, I don't see the need to waste fuel to achieve clean running, but that's only me, and I'm just One. I was sort of hoping the the Auto X Prize would bring something out into the open in the quest for 100mpg etc. I guess we'll have to wait and see. There have been for many years vehicles which achieve 100mpg, and much better, but they won't do any useful work.

I had some of the same early cars, and I never saw anything like 27 mpg. I don't have a lot of recollection on the corvair since both the odometer and gas gauge broke.

But the slant-6 dodge dart that I had was more typically 16 mpg. With a lot of highway miles and a light foot I could get that up to 18 mpg.

My 2002 Toyota corolla averages 36 mph with a heavy foot and 38-40 mpg with a light foot, both mostly highway.

So no, I don't miss the old days.

Good answer to you.

I agree 100%. I had some of the older cars and you were lucky to get 12 mpg highway and even less in the city. I know of many new very powerful V-8's, much more power than the older ones getting in the high twenties for mileage, way more mpg that could have been gotten before and are fully emmission compliant. If comparing to the late 70''s and 80's emmission systems and even engines then yes they sucked terribly. No power and milage was also poor, the main focus back then was passing emission test. The way then did it was to detune the enigne and lower compression. Back then the manufacturers didn't really know how to pass emmission and also make good power. Things have come a long way since then.

Another point, someone stated that the older cars were heavier than todays cars, not true. The same car today compared to the size of an older car is much more heavy than an older car. The reason they are heavier is because structural supports are added to get the car to pass the crash test as standards are much higher than they used to be.

I've numbed my brain on this subject for some time! I think 2 things contribute to bad MPG in moderns autos: - Power: Engines tuned to make high HP per liter are inherently thirsty. - Emission equipment: Catalytic converters and EGRs siphon energy. Exhaust gas recirculation systems on both gas and diesels waste energy because they force the engine to "re-compress" oxygen deprived hot (expanded) air. I don't have any facts to site, but common sense tells me that EGR systems aren't a good way to conform to EPA regulations.

A large issue with the older vehicles and whether they got good fuel millage numbers or not simply came down to who owned them and how they where maintained. The people who kept them tuned up and where not afraid to do some improvement tinkering where the ones who had the consistently higher mileage numbers that others never saw. I still think that holds true today as well. I tinker and modiufy andI get better numbers despite being a more agressive driver.

Those who did not and do not know how to do the work wont accept that the bigger or older vehicles are capable of far better numbers. And those who where able to do the work cant understand why others are so unwilling to do the changes needed to get better mileage and why they can be content with believing that it is impossible.

I modify and change every vehicle I have and I get good results from it. I know what I get and I have more than enough proof for reasons to continue to make those changes regardless of what others who think they know more say.

In regards to vehicles getting bigger and heavier BS! There is a whole legion of American made vehicles that have been getting smaller ligher and less powerful for 3 decades now.

Think about he old Cadillacs, Lincolns, Fords, Chevy's, Buick's, Pontiac's, Chrysler's, doges, Mercury's, Oldsmobile's, and other classic American vehicles from the 60's, 70's and early 80's. Every one of them had models of passenger cars that tipped the scales at over 5000+ pounds and had engines that where well into the 300+ Hp range. Do some homework and see for yourself.

Compare a 1960's or 70's Cadillac, Lincoln, or Chrysler luxury cars to todays versions. Take a look at the first Pontiac La-mons and what the last one looked like and then try and tell me that it got bigger and more powerful.

Post 1000 by the way!

I didn't say cars are gettin bigger, they are smaller but they are comparablely heavier per size than the older models which were of larger size. Do some checking yourself, compare the size and weight of an older car and then compare the size and weight to a modern car, you will find that most of the modern cars are heavier for their size due to added material for modern safety standards.

As for the old cars having 300 or so hp yes but that was rated at the flywheel not the net numbers you see today. Todays cars put out quit a bit more power than they used to and get a whole lot better milage per hp than a car putting out a similar hp rating years back.

I had a similar experience with an early 80's crown vic. 4b carb. My father bought a new 96 crown vic. same engine (5.0) but fuel injected with all computer controls. We frequently took the same trip at the same time to grandpa's ranch, (400 mi) My car consistently outperformed his by 2-3 miles per gallon. His car never reached the window sticker mileage. He brought it to the dealer to complain and convinced them to hooked up a computer to it and drove it in real world conditions. It was then that the tech told him all highway mileage estimates are gathered at 55 mph. At 55 mph it achieved close to window sticker estimates but not quite. Even that was not as good as the mileage i achieved at 70+. When his was driven at posted highway speeds of 70mph mileage fell off drastically. The tech said that car manufacturers design them for optimum performance at that speed and are largely unconcerned with real speeds people drive. These days its all about making the vehicle effecient at that magic speed of 55mph even though nobody drives at that speed on the highway

I had a '68 Cadillac Sedan De Ville that me and 7 of my buddies could go partying in back in the late 80's. It had a 472 and could spin the tires for blocks on end. It was big, ugly, square, powerful (I think it had about 375 HP) and HEAVY (7200 lbs!). It got 24 MPG on the highway. On a good day with the wind to my back my Grand AM (3470 lbs, 170 HP) gets about 26! Horsepower to petrol usage, I would take that 472 big block any day. Somehow these governmental fools who think they know it all about saving our planet do nothing but make matters worse every step they take.

If you get the same out of a gallon of gas, but on one alternative you spend an extra $2500 to build the car, add unnecessary weight, and make the car virtually "untuneable" are you saving the environment? Wouldn't it be a better program to change the steel in the cars to aluminum and plastic (which by the way, they also do on the "better" designs of late), use the technology we have to improve efficiency and ignore the "smog" limitations. With nearly half the weight, no smog crap, and no fuel injection, I guarantee that I could get better gas mileage with that 472 than I could ever get out of my Grand Am! I at the same time could impress people from time to time with my ability to accelerate.

IT IS A FACT/LAW OF CHEMISTRY that if you burn less gas you produce less pollution!

I maintain that the fuel injection in and of itself is probably not so much of a problem as it is the rush to smaller engines (power-to-weight ratio is nearly the same on both cars - probably the REAL reason the mileage is so close to the same), more smog protection, and cheaper construction methods. If we were allowed to create a V-8 with no smog crap and a fuel injection system designed to be efficient and drive a light car, I believe we could handily surpass the 30 MPG range. Imagine a 3000 lb car with 350 HP and 30 MPG!!!!! That is 40 to 50% LESS SMOG, plus it would perform like a Porche and cost less than the price of a Pontiac G-6. The loss of the pollution protection would more than cover the cost of the larger engine without it! I can't think of anything more likely to bring a grin to the face of ANY car driver.

Lets build it!!! Oh, yeah, the goons in Washington DC won't let us do that...

I like the way you think!

A couple of comments since my original post:

My recall as to those MPG's is accurate as I stated.

I did not ever getting into tinkering. I'd always do my own regular tuneups and only had a couple of screwdrivers, socket for the plugs, and a feeler guage. That's it.

I have known folks that had one of those big Caddies and claim that they got better than 20 MPH.

I omitted one car: Bought a new '78 Mustang II with a little V6. For the most part, only drove it around town for the first couple of months: 11 MPG. Holidays came up and drove it from FL to Philadelphia: 11 MPG. Don't remember if it had EFI. Didn't keep it long enough for a tuneup. The dealer repeated told me that there was nothing wrong with it. I kept looking for a gas leak.

One issue that is not being addressed here is that we are all assuming that the automobile is properly maintained and kept in tune to optimize mileage or performance or whatever measure you wish to compare. The truth of the matter is that far too many people who operate automobiles have no clue as to whether their vehicle is performing as it is designed to do. An improperly tuned engine is going to emit a lot more pollution than one that is properly tuned. In reality, in the perfect world, each car would be tuned to optimum for each individual driver's style and preferences. Since it is very unlikely that we will ever achieve ideal, or anywhere near that, some sort of standards must be established. One runs in to problems when one asks lawyers to write technical standards...

I have worked on most car and trucks manufactured over the passed 60 years.

The ratios are simply the heavier the car the greater the cubic inch (HP) needed to move the big beast. The big beast had a 39 gallon gas tank! Gas was manufactured at premium quality back in the day @ .69 cents a gallon.

Today auto manufacturers have no choice, they make smaller cars so they can reduce the cubic size of the power plant to facilitate the governments EPA requirements, which means the cost of the automobile has gone up 3 times and the true gasoline octane in the past 3 years has gone down.

This means your lucky if your fuel injected motor gets 36 miles per gallon do to the superior design qualities and the car having a 13 gallon tank filled with inferior low octane gasoline.

Again the quality of todays gasoline is regulated by our governments policy's. The real problem isn't the design, weight, or horse power of todays auto's.

Get the government out of the picture and all the problems will go away..

Tim

The problem with EFI is that it was not introduced to benefit fuel economy or power but to give accurate fuel delivery so that the catalyst would have astoichiometric mixture so that it would work properly.

Poor British Leyland spent a fortune trying to develop a lean burn engine that would not need a catalyst, but the NOx emissions could not be brought down low enough to satisfy the proposed regulations so catalysts became necessary. I assume the same thing happened to the Honda CVCC engine. The catalyst has killed a lot of engineering ingenuity in my opinion and performance and economy has suffered.

i think that I can answer just about everyones questions about EFI and MPG. The two reasons, yep just two, that MPG has gone down over the years is because of Emissions and fuel. In order to get the emissions numbers, that some guy who most likely doesn't even like cars came up with, you have to use more fuel. EFI allows us to adjust when the fuel is added in order to meet the emissions requirements. It is kind of sorry that it has taken auto manufactures close to 35 years to nail down how to produce the power and MPG numbers that we once saw with carbs.

Also, MPG numbers are never constant there are way to many variables such as engine efficiency, transmission loss, drive shaft loss, axle loss, bearing friction, brake drag, tyre pressure, type of tyre, Size of tyre, wheel weight and so on........

Fuel is the other reason because the removal of lead and the reduction of octane ,or cetane, numbers has caused the amount of fuel needed to produce the same result to increase.

So when you marry big business people, who wont let the car guys go nuts with tunning, and lower fuel performance you get the car of the 70's, 80's, 90's. no performance and horrible MPG.