Vehical MPG

"Why are we still getting around 25 to 32 MPG on the highway?"

Who's getting 25 to 32 MPG? The auto industry wants to know so that they can fix that. Its way too high of number!

I don't think your math is exactly correct but still it goes along with may argument of why does a 80,000 pound semi truck and trailer with ten times the aerodynamic drag of a small car and 27+ times the weight only get 1/4 to 1/5th of the fuel mileage at the same highway speeds and driving conditions?

According to the on-board computer, my 2004 Volvo S60, with the non-turbo 5 cylinder engine on 87 octane gas, gets an average of 29 MPG on the highway, driving 40 miles each way. On the flat at a steady 65 MPH it gets better than 35 MPG. Accelerating while in traffic can drop the MPG to half the normal average.

Driving up a hill at 20 MPG then coasting down the other side at "99 MPG" results in only 40 MPG average. The same with acceleration. Easy on the pedal!

"Why are we still getting around 25 to 32 MPG on the highway?"

Because that's reality.

I'm have difficulty with this, "the above 2,072,148.73 CI/Gal has expanded to 3,122,458.884 CI/Gal yielding 350.364 MPG."

You would have us believe that your engine has manufactured more new air than my calculator can compute?

The increase in air volume is the reduction in air pressure from atmospheric to the 10 inches of mercury. For the same quinty of air (by weight), there is an increase in displacement with the reduction in air pressure.

And how does this affect stoichiometry during combustion? The 10"Hg is only in the intake manifold. Nothing happens there.

Enlighten me.

But at 10" mercury the quantity of air by weight is not the same as at atmospheric pressure. The volume stays constant (= engine swept volume), it's the the pressure and mass of air that change.

Cheers.........Codey

At one intake stroke per 2 revolutions, 327/2 x 3260 = 533,010 in³/mile. (Not 8883.5)
Oxygen constitutes 20.9% of air.
Adjust further arithmetic accordingly.

Ref my post 1 minute ago, just noticed you'd also said it.

You're right, I was going to post that but you got there first! 304 ft³ = 525300 in³. OP's figure 8,883.5 CI/mile is a factor 60 out.

Cheers.........Codey

If it were a constant mass of gas expanding from 30" mercury absolute (zero vacuum) to 20" mercury absolute (10" mercury vacuum) your volume figures are about right. But it reads more like you mean 10" mercury absolute, which would give expansion ratio 3 x, not 1.5 x.

But in any case, as indicated in #9, the volume flow stays constant, the mass of air (and fuel) go down in proportion to the absolute pressure. And where is the 10" mercury from? Without checking in detail, it looks like the pressure is lower than 10" mercury, giving lower fuel input and the sort of fuel consumption seen in real life.

Cheers.........Codey

Not sure of the basis for your comment "Engines from the days of the 327..." The 5.3L used in current Chevy & GMC pick-ups, SUV's, Camero, et al is 327 c.i.d.

I gather you are rather young.

The 327 was produced from 1962 to 1969. It has a 4" bore and a 3.25" stroke, and has more lore associated with it than perhaps any other Chevy engine, having been the standard Corvette engine for that period, and having been a favorite swap for hot rodding almost anything. It's calculated displacement rounds to 327 ci. It is a member of the generation 1 "small block" Chevy engines.

The 5.3L engine's displacement is 325 ci. There is not a single significant component that the two engines share (and of course, there is nothing remotely like the same "lore" -- you don't hear songs on the radio about 5.3 liter engines). http://forum.miata.net/vb/showthread.php?t=274715

I wouldn't say that just because some newer models of vehicles are getting more efficient that it honestly equates to every newer vehicle being equally efficient. Just the same saying that just because some old engine designs are very inefficient that it means that all older engine designs are as equally inefficient.

We have about 20 -30 years of emissions compliant engine designs where far far too many became well noted and well known for being absolute fuel pigs despite their lack luster power or vehicle mass numbers.

I for one have been around a few too many mid sized cars built between the late 1970's all the way up into the early 2000's that despite having half the mass and half the Hp of many old full sized pickups still got similar fuel mileage numbers.

On top of it I would hardly call the Prius a outstandingly efficient vehicle considering that in the late 70's and early 80's they typical Volkswagen Rabbit Diesels, along with many others, where pushing the same average fuel economy numbers with similar lackluster body size size and engine power despite having zero hybridized drive train design to maximize their efficiency.

I wouldn't say that just because some newer models of vehicles are getting more efficient that it honestly equates to every newer vehicle being equally efficient.

No. But fuel efficiency is a market driver in many vehicles, and in those where the market is close and competitive, the engine efficiencies from one car to the next are almost identical, both in steady-state dyno rests and in epa cycles. That's because the manufacturers design to the EPA tests, which happen to correlate with (synthetic) average real driving (because it was based, long ago, on data logging from actual driving sessions.)

You'd be hard pressed to find a typical SI car engine (in which efficiency is an issue (filter out Ferraris, Hummers, etc) in which the peak efficiency differs by more than 1%-2% on either side of 31%. There is no conspiracy by the car manufacturers to make less efficient vehicles, and the things that I am doing to my little prototype engine to improve its efficiency are the same things I am doing to improve its emissions. Stated another way, my only realistic route to high efficiency also happens to be the route to low emissions. This trend is what gives us average, feature laden family sedans that can blow the doors off old 409's, 389, etc. (and even late eighties "super cars" -- Motor Trend tested family sedans against of Ferraris, etc, and the family sedans won.)

Find a bsfc chart from any production SI engine of the 50's, 60's, 70's, 80's, 90's that is better in either peak or breadth of peak than a current engine. Can't be done.

The Rabbit diesels were a fraction of the mass of the Prius, yet still did not get the same fuel efficiency as the Prius in the same tests. (The 1985 Golf diesel gets 31 city , 41 highway... stunningly worse in the city case, given the low mass, to much worse, in the highway case, than the Prius.) And obviously, the Rabbit is a diesel. The current VW diesel engine is more efficient than the Prius engine, but the Prius engine is in a class of one for SI engine efficiency. The major reason why the Volt gets crummy mileage (it's not enough heavier than than the Prius to justify its dismal mileage [37 vs 50 mpg]) is that it's engine is lower efficiency. Chevy readily admits the engine is a POS that they found on the shelf, and that they spent development time on other things.

The current Prius is in the same weight class (3100 - 3500 lb) as a light 62 Chevy (Biscayne, manual trans, 283, no air). The Chevy got 15 mpg, the Prius gets 50. That's a large difference in vehicular efficiency.

Sorry but I have driven a Prius and unless you intentionally drive it to get high mileage it gets about the same mileage as any other car its size.

I am not the only one who has found that out, I just happen to be more vocal about it.

Here is my personal experience and review of having driven one like a normal person that actually likes to get some place in a practical time frame.

http://cr4.globalspec.com/thread/63109

Individual personal experiences are not useful as a measure of the efficiency of a car model... they measure driver behaviour, location, weather, terrain, tire inflation pressure, gasoline age and formulation, altitude, etc. Only slightly better are dyno runs on variable load machines that can be held at a constant load (If you use 45 mph and a 3% grade, you can get close to epa numbers.) Better, by far, are the EPA test cycles run in an EPA certified lab. The last are the only tests that come close to being repeatable and representative of the actual performance of a car model rather than the driving technique of an individual. They include starts, stops, acceleration, deceleration, idling, etc... all the facets of real driving in a highly repeatable format in which speeds and loads are monitored second by second.

My Honda van gets 6.2 mpg sometimes and 99 mpg at other times. Somewhere in between is an average for me. Somewhere else between those numbers is an average for someone else.

The average of 136 Prius drivers who sent in personal results on 2010 Priuses was 48.5 mpg, extremely close to the EPA rating of 50 mpg. The average of 14 Camry drivers was 26.6 mpg, also extremely close to the EPA rating of 26 mpg. For the Corolla: 29mpg EPA, 32mpg for average of 24 users. Again, very close. For most cars, if the user results are averaged to balance the lead foots with the grannies, (and if there are 10 or more respondents) the number comes very close to the EPA numbers.

"Individual personal experiences are not useful as a measure of the efficiency of a car model... they measure driver behaviour, location, weather, terrain, tire inflation pressure, gasoline age and formulation, altitude, etc."

Unfortunately I and most of the rest of the world of people who drive tend to measure fuel efficiency or lack there of by what, when, how, and where we drive and at the most basic core that part where we pull into a gas station and spend our money only to find that the idealistic estimate numbers rarely if ever are close to what the factory said they would be.

I don't care what the factory tells me my vehicle should get. I care about what it does get and by what means can I change that number to my advantage by any modifications to the vehicle as practical.

Thank you for the information Gary, you are right on. I hope you get an answer soon.

I've been waiting for an Answer for over 10 Years ! Again, not one "Concerned EnvironMENTAList, Oil Company Executive or Politician will dare to even attempt to answer my question ! Thanks for the reply ! Gary

Perhaps I'm being a bit slow, but what exactly is the question? Looks more like a lot of statements to me.

BTW are you the OP?

Cheers.........Codey

I also suspected 'Gary T Kirkland' was the OP. On closer inspection I doubt he is.... if he is the OP, he put more thought into the deception than into his '10 year unanswered question'.

The OP did not spell 'vehicle' correctly, Gary T consistently did.

The OP did not spell 'stoikiometric' correctly (I'm not certain i have either,but it is at least phonetically reproduced), Gary T did not attempt it, but his comments strongly suggest Gary T. is unfamiliar with the word.

The OP is proficient in utilization of the space bar and the creation of new distinct paragraphs. Gary T. Kirkland could use some practice in those areas.

Although my intent is to establish a high probability the OP and Gary T are not the same person (and not simply to call out errors) I know that noting spelling or punctuation errors others have made still opens me up to being slammed for similar errors I have made. Fire away, I will not shirk legitimate criticism.

You don't seem to indicate the energy required to operate the vaporizer.

The only Energy required to operate the vaporizer is low pressure air.It's all described in the posts I have made.

This is exactly the kind of non-answer that sets everyone off.

Hey - What do you mean "everyone"

I'm quite relaxed [these days] reading how everyone else has thermodynamics totally backwards. I love the concept of getting more energy by burning it 'richer' and colder'.

_{Suppose you've noticed Das is back and concerned about reaching CO2 triple point inside a power station flu.}

Some interesting reading here related to the how and why of different A/F and spark timing for different applications.

http://autospeed.com/cms/title_Tuning-AirFuel-Ratios/A_1595/article.html

and

https://www.sr20-forum.com/tuning/16056-why-i-tune-12-0-1-f-ratio-0-82-lambda-why-you-should-too-all-welcome.html

and

http://www.europeancarweb.com/tech/0507ec_chip_tuning/fuel.html

Take it for what it's worth.

this is the question of the millennium!

but I don't think that any of you gentleman's remember to note that most of the energy on the combustion is dissipated on eat, so as your bucks

Back again eh?

you still haven't brought any data or science to the table?

the page you linked to is from 95, where you try to sell your book for $20

Mr. Kirkland,

Your response makes no sense whatsoever, nor does it answer any of the questions or objections that have been addressed to you. Please respond substantively to the following or concede your utter lack of comprehension of basic thermodynamic principles:

You again refer to "atomized state".

1) Please respond to the repeated correction that the atomized fuel is, in fact, vaporized prior to combustion. How do you justify continuing to ignore this fact and referencing atomization as the cause of inefficiency?

You state that a stoichiometric air/fuel ratio results in only 10% of the fuel being "utilized".

2) Define specifically what you mean by 90% of the fuel not being "utilized". Not burned? 1st Law efficiency? 2nd Law?

3) Why, specifically, is this so? Nothing in the link you gave gives any explanation other than non-scientific mumbo-jumbo.

You state that a stoichiometric ratio results in fouled plugs and engine wear.

4) By what mechanism, specifically, does stoichiometric operation - according to you - cause plugs to foul?

5) How do you respond to the empirical evidence that all modern vehicles with closed-loop control of mixture consistently run for 10's of 1000's of miles, in all conditions, without fouled plugs?

6) By what mechanism, specifically, does stoichiometric operation - according to you - cause engine wear?

7) How do you respond to the empirical evidence that all modern vehicles with closed-loop control of mixture, if properly serviced, consistently run for 100's of 1000's of miles, in all conditions, without excessive engine wear?

You state that 100-1 ratios result in more than doubling fuel economy, more power, and a lower combustion temperature.

8) How do you respond to the loooong proven fact that 100-1 ratios will not sustain combustion at anything approaching engine operating speeds? Nothing you've referenced mentions stratified charges or other solutions. Where is your data that contradicts a century of science?

9) By what mechanism, specifically, does a 100-1 ratio - according to you - result in more than doubling fuel economy?

10) By what mechanism, specifically, does a 100-1 ratio - according to you - result in more power?

11) How do you respond to the fact, known for centuries, that the theoretical maximum efficiency is a function of combustion temperature and that the HIGHER the combustion temperature, the higher the efficiency? By what thermodynamic mechanism do you propose that lower combustion temperatures can increase efficiency?

Your phrase, "than with natural gas or propane" seems to imply that the benefits that you claim for 100-1 gasoline ratios are realized with these gaseous fuels.

12) Is this correct?

13) Can you provide data that NG or propane fueled engines produce substantially more power and/or use substantially less fuel than gasoline engines per unit heating value of their fuels?

You stated that a 100-1 mixture, "burn(s) the same exact color pattern of butane, blue to yellow to orange".

14) What is this supposed to prove? How does it prove it? Why do you reference this observation while ignoring all of the relevant matters?

And finally:

15) Why have you not, IN TEN YEARS, learned one iota of basic thermodynamics?

A failure to respond substantively to these questions is a defacto concession to everyone except diehard cranks.

A failure to respond substantively to these questions is a defacto concession to everyone except diehard cranks.

I resent that accusation

Son of editor Crankshaft