Low Power Output and High Displacement, a big debate.

[Mr. CoolFiat]

I've read this thread, but did they have ethanol fuel in the 80's? Or is this just brand-new? Because if you put Ethanol in a car it starts ****ing up the engine. I HATE ETHANOL.

 

[niky]

Depends on the engine. Newer engines have better rubber and valve seals and can withstand ethanol. Still doesn't stop it from being hygroscopic and going bad as quickly as weak beer...

 

[Cano]

Anyone else find it humorous that one of the biggest contributors to a thread entitled, "Low Power Output and High Displacement" is named after a car that, in 1976, had 215hp from a 7.5 litre engine?

Hey, leave the thing be. Not everything on the road had 450+ pound-feet of torque as well. TO THE FRONT WHEELS.

 

[CSLACR]

Go to a site like Ecomodder. Half the forum seem to quite comfortably beat EPA figures, many without even trying.

In fact:

That was my old Miata. Few low results there (the 17mpg one was anomalous - probably a poor calculation on my part), but a fair few at roughly 10mpg more than EPA. And plenty at more than 5mpg above EPA, in mixed driving. And I don't hypermile, I just drive economically most of the time and have fun when the opportunity presents itself. I'm pretty sure if I'd put my mind to it I could have consistently achieved 10mpg above EPA.

Not all cars can do that of course, but I suspect rather more than "none" can.

But your comparing tankfuls of seemingly un-monitored highway vs city mileage, to EPA combined estimates.
What I'm saying is driving 100% on highway (cross country) cruise on and cruise off, I've never seen 10mpg over highway estimate.
Entirely to many variables in city and combined to get truly accurate results IMO.

Did I ever say anything like that?

I mention EPA-tailoring because many cars are tailored to the EPA regimen. The first-generation Honda Fit isn't.

I've no way of knowing for sure, I know Honda's all have quick gearing (at least somewhat older and before) but this also applies to the 95 Civic, which is why I see it as equal.

Still, the point stands. Estimating a new EPA number on some arbitrary percentage calculation ignores the fact that mileage can't be calculated that way simply because the cruising speed changes. If a car is at optimum cruising speed at the old EPA cruising test and beyond that (and out of lean-burn mode and into the regular MAP-regulated mode) at the new cruising speed, then simply applying a percentage change will not realistically reflect that change.

But we don't know that's what the EPA did, they don't specifically (that I saw) say exactly how they re-calculated it.
But it's a fair point if they did, somewhat.
Somewhat, because a car designed for optimal efficiency at 55mph won't suddenly drag way down at 65mph (typically) there is a noticeable difference, just not huge.

All my fuel testing is done with GPS-corrected odometer readings and full-tank to full-tank testing. The only thing I'd be bragging about here is the insane amount of money I spend to test fuel economy on media test units when most other drivers are content to read the trip-meter and make a guesstimate off of that.

I wasn't specifically referring to you, if you dig through the site I linked you'll find people claiming 70+mpg on the highway with hybrids, and generally ridiculous claims.

Sure, it's not quite as accurate as the guys who drain gas tanks, run the car dry, fill up, then weigh the remaining fuel after a run... but... seriously, that's overboard.

I find the GPS not even necessary, long ago I questioned speedometer (and subsequently, odometer) readings, I then learned U.S. highway mile markers are very inconsistent, I've seen them jump 5 miles in 3 miles distance, the trick is, over a long trip, they add up.
The difference in my current speed/odometer reading and measured mileage by directions and highway signs over long trips is less than .5%, if there's any difference at all.
So now I just fill the tank, check fuel put in, and divide the mileage by gallons of fuel, inaccurate for a single tank, very accurate for dozens of tankfuls in a row combined.

So 55 mpg in urban driving isn't beating the Fit's numbers by dozens? City driving is difficult to gimmick because of the acceleration cycles and idling cycles. Cars spend less time in lean-burn and cruise on the city cycle than on the highway cycle. Mazda fought with the EPA because their "city" cycle doesn't show the full effect of their stop-start technology. If you can get decent city numbers, then the car will be fuel efficient.

Is that a U.S. spec car? And like I said, I've personally never seen anywhere near those gains, and frankly, I don't think for a second a U.S. spec Fit will see 55mpg highway, let alone city.
Now, if by urban you mean cruising at 35-40mph in 5th gear, yes. I believe that without a doubt, I've seen 4 cylinders with manuals get much higher than highway ratings in that range, it seems to be a sweet spot most people don't know about.

The gimmicking here is the shifting. The EPA allows ATs to shift whenever they want... so manufacturers can program shift points to take advantage of this. But the EPA gives set shift points for manuals. Some manufacturers can tune their engines based on this... hell... a lot of US-market engines we've tested make a lot of power up to 2500 rpm, drop-off between there and 4000 rpm in the lean-burn area... then make power again after. Gimmicky? Yes. Does it suck? Hell yes, I hate uneven power bands.

Well, most people driving manuals don't shift early enough by a long shot, so I see their point. My AT shifts into lock-up at 29mph, a very useful tool, if only I had it for second gear I'd be set.

But in the real world, it does make for better economy. Much more than a gimmicky EPA-friendly cruising gear that makes sixth/fifth too long for proper econo-cruising (which is best done at speeds below the EPA test speed).

But in the U.S. most highways have a limit of 65mph, which means (myself included) almost everyone goes at least 70mph, so it does benefit, just not as much as a quicker gear at a lower speed could.

Very difficult to prove... as the level of engine technology can vary very widely from manufacturer to manufacturer... the new diesels we have here tend to outperform their gasoline counterparts by 5-10 mpg (depending on conditions) while providing more useable torque over the entire rev range.

The big problem, again, is up-front price. The price of diesel is too market dependent to be a big talking point. In any event, even in markets with expensive diesel (like the US), the economy of diesel vehicles still gives them an advantage. But there's often a $2000 - $4000 premium for the engine versus a gasoline engine with the same power output. (Still better than the $4000 - $6000+ hybrid premium)*

It bears remembering that a 170 hp turbocharged diesel is going to give much better acceleration and economy than a 170 hp naturally aspirated gasoline engine. Hell... that porker of a Focus weighs nearly 1.5 tons, 500+ pounds more than my Protege... and while my car makes 175 hp, the Focus outdrags it with "just" 135.

And it still has economy similar to a much smaller gasoline engine.

These new direct injection turbocharged small-displacement gas engines might be able to match diesel economy and power, but they will obviously carry a price premium, too. I can't wait to test one, myself.

Best place to see the comparison? UK market publications. They often have very balanced reviews of gas and diesel cars... but given the high tax there, the price premium of diesel is amplified.

In the end, in economical terms, diesel might not be worth it... long-term maintenance and running costs partially negate the fuel savings, and the upfront price premium will always be a problem... like hybrids, diesels will most benefit those who do a lot of miles a year... but payback time is often much shorter, and... well... because turbo. Who doesn't love a rush of torque to the head?

Now if they could only make them sound nice.[/color][/b]

*Price premiums depend on the cars... on luxury cars, the premiums are hidden behind the huge markups, so they're mostly non-existent. On economy cars, the price difference is often a significant portion of the purchase price.

You and RJ don't want to hear my thoughts on Mazda powerbands, and under performance. So I'll leave it at "RX-7's were awesome", and I like the newer FWD, I think it's the 3, with a turbo and 260hp.

As for Diesel, I think if nothing else, the cost + interest will rob anyone of any potential savings. 7 year loans make 2K turn into 4K, let alone a 4K difference.

BTW - tidbit on ethanol, did not know, makes me happy I usually use 93 octane, which has either less or no ethanol.

 

[homeforsummer]

But your comparing tankfuls of seemingly un-monitored highway vs city mileage, to EPA combined estimates.
What I'm saying is driving 100% on highway (cross country) cruise on and cruise off, I've never seen 10mpg over highway estimate.
Entirely to many variables in city and combined to get truly accurate results IMO.

My driving has always been mixed - pretty much every tankful contains at least one freeway trip, and a bunch of city stuff. You'll note my overall combined figure was 4mpg above average, and that was with some pretty poor tanks in there - city only, stop-start commutes (as a result of the job I had at the time). So in fact, even in city-only driving, I was managing to match the combined EPA figure...

And I wouldn't even say that freeway trips are a massive advantage, since I've never owned a car that's been hugely economical on the freeway unless I slow down to 60-odd MPH (apart from maybe the Fiesta I had, but the Mazda and Fiat have both been pretty high-revving on the motorway). I've never used premium gas, just regular, so there's potential for even more fuel savings if I did (although obviously, initial cost would be higher - which is why I never bother).

And I'm surprised you wouldn't expect to see 10mpg over on cross-country trips unless you live somewhere incredibly hilly or twisty, since "highway" (as opposed to "freeway") driving in the UK means 60mph limit roads, and on those sort of roads I'm pretty certain I could get 10mpg over. Plenty of opportunity for carrying momentum and good planning can minimise excessive braking or acceleration, and lower speed limit means lower average speeds, lower revs.

Before it comes up, I'd say my car was comparable to a U.S. spec version. A first gen Miata is the same pretty much anywhere.

 

[niky]

The difference between 55-65 mph can be moderate or it can be large, depending on where the engine transitions between closed-loop and open-loop and aerodynamics.

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The US-Market Fit... hard to say. What I know is a GD with the identical 1.5 MT powertrain will hit 30 mpg if you drive the balls off of it in an urban environment, and it will hit 48 mpg on the highway... so I'll leave it at that.

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Highway cruising... well... that's a problem. If traffic slowed down to around 50 mph, fuel economy would shoot up exponentially. On cars I've driven, the difference between 50 mph and 70 mph in terms of economy was often in the double digits in terms of mpg. But of course... that's America...

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70 mpg on the highway with a hybrid is difficult, but achievable. It's a game amongst Prius owners, some of whom play around to see who can hit 80 or even the mythical 100 mpg. Hybrids respond better to pulse-and-glide than regular cars because of the engine deactivation mode. If you drive it the normal way... stay in the power all the time to maintain cruising speed, then economy is going to suffer a lot.

Do note: most people see pulse-and-glide as anti-social... and extreme forms of this are outright dangerous.

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There's a site for the ethanol-shy ones or for people who can't stand the fuel economy hit they take with ethanol. It maps out all the stations that sell ethanol free gas... forgot the url, though.

 

[CSLACR]

Just a general response, in the U.S. as far as I know highway is pretty universal, freeway is more accurate though.
As I said in my last post, I know best mileage isn't obtained at 70+mph (some states hit 75, which turns into 80-85mph), but it's what we need to do to a certain extent, 1200 miles doesn't come quickly even at 75mph, let alone 40-50mph.

But when I compare my mileage, I compare it on equal terms. Saying I can do better at a different speed is irrelevant, because you're comparing apples to oranges.
I also think weight was left out, which is an extremely important factor in best speed for mileage, potentially more important than aerodynamics, depending how severe. A heavy aerodynamic car actually can peak at speeds much higher than a lightweight box, and a aerodynamic lightweight will still peak at a lower speed than an aerodynamic heavy car.

As for Prius', the other day I watched a cigarette butt fly out the window of one, and the tiny shred of potential respect for Prius owners flew with it. As for their "game", again, it depends on the definition of highway, but most I've heard of achieve less than EPA estimates, but those are probably the ones comparing apples to apples, i.e, the same speed as the test they're comparing against.

 

[Pupik]

The difference between 55-65 mph can be moderate or it can be large, depending on where the engine transitions between closed-loop and open-loop and aerodynamics...

Highway cruising... well... that's a problem. If traffic slowed down to around 50 mph, fuel economy would shoot up exponentially. On cars I've driven, the difference between 50 mph and 70 mph in terms of economy was often in the double digits in terms of mpg. But of course... that's America...

My Scion xD's 1.8-liter is similar in this respect (typically, A/C on 95% of the time)...EPA figures are 27 city and 33 highway:

Cane it, city driving: 26 mpg. 25 if you have to do a lot of idling/bad traffic jam.

"Average" city driving: 28-30 mpg (flog it a few times, mostly just keep up with or away from traffic)

Mixed highway/city driving: 30-32 mpg (usually at 31.5)

Highway only/mostly: 28-35 mpg (keep the speedometer at 85, you'll get 28 with the A/C on, 30 without). Drive at posted 70 or 65, and you'll get 35-39 mpg. That means exactly at the limit (used cruise control)​

The big difference is how you drive the highway speeds...at the posted limit (generally, this will keep up with 50% of the traffic in Florida, and you'll still pass a few vehicles). The difference between 65mph and 80mph is really just a matter of which lane you choose to drive in, but translates to a 7-8 mpg difference.

Rural driving (usually 55-60 mph, sometimes dipping to 45-50 mph): 34-42 mpg. This is usually windows-down, no A/C on. Occasionally, I've hit 45 and weird numbers like that, but they usually disappear by the time I find a curvy or unusual back-road. The speed limits can vary greatly, and there's some places the limit/slow-vehicle-in-front-of-you is very slow for longer periods of time. Or the scenery is just...interesting. This really varies, but it also depends on the types of roads and attitude I have when drive.

Cruising along the ocean at 30-35mph (it's rare you could ever go quicker on these roads, although stops are rare in most places): 40-44 mpg. Once I got 46.5 on a cool Sunday afternoon/evening, windows down, enjoying the weather and nice cars.​

These are off the charts, because there's no real government study done for rural driving. In other cars, I've always gotten stellar mileage with places that aren't as quick as an interstate highway, but feature much less stopping than city driving. One other thing I've noticed is that once an engine gets up to the "right temperature", the fuel economy generally improves somewhat. City driving for trips less than 15 minutes doesn't seem to produce figures as good as those when the engine has been running for say, 30 minutes or more.

Still, in the spirit of the original poster's thread title, 128hp from 1.8 liters isn't amazing by today's numbers, but would have been above-average 25 years ago. Keep in mind that most "supercars" like the Lamborghini Countach produced ~420hp, a Ferrari Testarossa put out about 450hp, et cetera. Now, Cadillac, BMW, Lexus, Mercedes-Benz all make a motor or two very near those figures for half the price (even considering a then/now dollar-for-dollar scale). Engines have come a long way...weight gains are another thing, fuel economy is here and there. (One thing's for certain, just about every car handles better than they did 25 years ago...)

 

[Mr. CoolFiat]

What type of tests did the EPA and SAE use to measure the Fuel Economy and the Output, respectively? How did they change? Because that must have contributed to making engines "look" less powerful.

 

[Keef]

My Scion xD's 1.8-liter is similar in this respect (typically, A/C on 95% of the time)...EPA figures are 27 city and 33 highway:

Cane it, city driving: 26 mpg. 25 if you have to do a lot of idling/bad traffic jam.

"Average" city driving: 28-30 mpg (flog it a few times, mostly just keep up with or away from traffic)

Mixed highway/city driving: 30-32 mpg (usually at 31.5)

Highway only/mostly: 28-35 mpg (keep the speedometer at 85, you'll get 28 with the A/C on, 30 without). Drive at posted 70 or 65, and you'll get 35-39 mpg. That means exactly at the limit (used cruise control)​

Our Corolla routinely nets 35+ mpg at 72 mph, where I like to cruise. Dad says he's seen 40 mpg at 65. Our mixed driving usually stays between 31 and 34, somewhere in there, almost exactly like yours.

 

[CSLACR]

What type of tests did the EPA and SAE use to measure the Fuel Economy and the Output, respectively? How did they change? Because that must have contributed to making engines "look" less powerful.

I don't think the EPA has anything to do with power figures, but the "SAE certified" is relatively new, it specifies what must be attached to the engine before a dyno test is run.
This started because of manufactures like Toyota, (they were mentioned) that inflated their numbers by running dyno before they attached anything to their engine, such as power steering pumps, and I'm not sure what else.
It inflates the numbers because every accessory run increases drag on the engine, and reduces effective power, so while a bare engine make produce 200HP, once you strap on all the engine driven accessories, the power output may only be 185HP.

I don't know what all manufactures were guilty, I do know most of them were Japanese if I recall correctly, and specifically, I recall the Mazda RX-8's quoted power going from 246hp down to 232hp. (or something close)

 

[Greycap]

I can as well use my own car as an example here, seeing that it's relatively low powered and has a relatively high displacement engine. Meet the Flying Snowball, my trusty Volvo 240 estate.

The body mostly designed before 1975, the engine designed before 1985, the entire thing assembled in late 1991. It'll have its 20th birthday this year.

Under the bonnet is a Volvo B230F, the well known red block engine, with a displacement of 2316 cc, a 8V SOHC head and a stock power output of 116 bhp. That's almost exactly 50 bhp per litre - miserable by today's standards. This example has been slightly improved with a more aggressive cam (from a later red block variant) and now puts out an estimated 130 bhp - around 55 bhp per litre. Still quite miserable. Choked with a catalysator of course, getting its fuel through a fully electronical multi point injection system though.

To add to the seemingly unavoidable catastrophy it has the aerodynamical efficiency of a stone church from the Middle Ages, is reasonably heavy (well, around 1500 kg with a full tank and a two man crew, not that bad actually) and has a reputation as a gas guzzler of the worst kind. Most people would guess something like 20 (US) or 25 (UK) mpg on the highway.

But the things don't add up... no doubt the powertrain as a whole, especially the engine, is still in full check after all these years and I probably know what I'm doing with it when it comes to getting good mileage. I drove 380 km last week, consuming 28.5 litres of fuel in the process. That's 7.5 litres per 100 km, roughly 31.5 mpg US or 37.5 mpg UK.

To make it even more weird it didn't necessitate any out-of-this-world tricks, the only things I consciously do to minimize fuel consumption are reducing throttle when going down long hills - when the mass gets moving it'll hold the speed even with the throttle fully closed - and not increasing throttle for uphills if there's nobody behind me. It doesn't matter a bit if I'm doing 100 km/h or 95 km/h at the top of the hill but it makes a difference at the fuel pump, and the car will gather the lost speed back at the next flat section anyway.

 

[niky]

What type of tests did the EPA and SAE use to measure the Fuel Economy and the Output, respectively? How did they change? Because that must have contributed to making engines "look" less powerful.

Gross horsepower was engine output without any accessories at all. SAE net requires accessories to be attached and for the test to be run at a specified temperature and humidity. That's the change that caused US automakers to drop whole shedloads of power back in the heady V8 days.

There are SAE corrections if you don't have the proper testing environment... but this produces ambiguous results... as we've seen with the Nissan GT-R, which already corrects its own engine mapping given extremely hot or cold weather, and which has led to some interpretations that the motor makes more than it is claimed to.

The recent downgrade for Toyota and Honda was due to a clarification by the SAE regarding testing procedures... which closes a loophole which allows you to run less or thinner oil, and with premium gasoline. In other words... those cars actually would make the power, given the right conditions. It's a voluntary standard. And that Toyota and Honda volunteered to follow it shows that they weren't actually consciously trying to hide anything.

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Mazda's boondoggle is different. Their issue was that they tested for horsepower on global cars, before applying emissions restrictions specific to some markets, like the US, which is why they've had to revise power outputs for some cars. Even now, the power output for the US Miata and RX8 are different from global. Furthermore, Mazda, like Nissan, has intelligent engine controls that adjust for conditions. Sport Compact Car has reported that the MX-5 pulls up to 15 degrees of timing in poor running conditions.

Poor running conditions can be interpreted as: Piss-poor gas, banging off redline and not enough air passing through the radiator. In other words: On the dyno taking the SAE test on non-premium gasoline.

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EPA is completely different: It's a test done on the dyno, but it's all about economy.

To sum up: you have a city and highway cycle, with specified stop, idle, acceleration, cruising and deceleration times. Test drivers accelerate exactly as the EPA specifies, and shift exactly as the EPA specifies, too... EXCEPT when the vehicle is automatic or it has an eco-shift light.

This gives an unfair advantage to automatics... and some cars can be geared properly for real-world economical acceleration, but still not for the EPA cycle... this is why we talk about "gimmicking" the EPA cycle. One infamous gimmick is the Corvette 1-4 shift lockout... which forces you to shift straight to 4th gear from first. In reality... hypermilers like to skip-shift, too... but if you do this, you should do it for all similar cars. The EPA doesn't... thus the Corvette appears more economical than most other cars with the same power.

The recent revision that caused economy numbers to drop includes harder acceleration and more stop time on the city cycle, and a higher cruising speed on the highway cycle. The highway cycle I'm sure of, but the rest, well... it's been a while, so I can't recall specifically the change.

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The reason I don't like the highway cycle is when we test vehicles, we often don't get numbers proportional to the highway cycle on the highway... some cars underperform, some overperform. There's no set pattern. On some cars, to match their fantastic highway economy claims, you have to drive with just 1% throttle, trying to keep a flickering ECO light from going out. Not fun. On others, you just get in, zone out and drive... bam... perfect economy numbers.

But the city cycle appears proportional, at least for non-hybrids, because it's a bit harder to fake... and like I said... if you can program a car to do well on the city cycle (what with programmable engine maps, drive-by-wire throttle and etcetera), it will actually do well in real-world city driving... most of the time.

 

[CSLACR]

This gives an unfair advantage to automatics... and some cars can be geared properly for real-world economical acceleration, but still not for the EPA cycle... this is why we talk about "gimmicking" the EPA cycle. One infamous gimmick is the Corvette 1-4 shift lockout... which forces you to shift straight to 4th gear from first. In reality... hypermilers like to skip-shift, too... but if you do this, you should do it for all similar cars. The EPA doesn't... thus the Corvette appears more economical than most other cars with the same power.

But don't you think the 1-4 shift skip (also found on others) encourages drivers to save fuel by skipping two gears?

As for the rest, it's quite clear you dislike EPA testing methods, so I'd like to hear potential thoughts on how they could be improved.
I'll start by saying they somewhat have to enforce uniform acceleration and driving speeds for each car, because the general public is going to drive them mostly the same anyway.
I don't think it'd be any better to have tests done with manufactures having free reign of how to set the best numbers they can get driving however they please, as those are even more unrealistic conditions than the current standard.

 

[homeforsummer]

But don't you think the 1-4 shift skip (also found on others) encourages drivers to save fuel by skipping two gears?

Nice thought, but how many Corvette owners are honestly going to use it? Nobody with a Corvette goes boasting about their fuel economy... and if someone bought one on the basis of fuel economy, they've bought the wrong car.

 

[niky]

But don't you think the 1-4 shift skip (also found on others) encourages drivers to save fuel by skipping two gears?

As for the rest, it's quite clear you dislike EPA testing methods, so I'd like to hear potential thoughts on how they could be improved.
I'll start by saying they somewhat have to enforce uniform acceleration and driving speeds for each car, because the general public is going to drive them mostly the same anyway.
I don't think it'd be any better to have tests done with manufactures having free reign of how to set the best numbers they can get driving however they please, as those are even more unrealistic conditions than the current standard.

Most Corvette owners unplug the solenoid for the "skip shift".

Obviously you don't give manufacturers free reign... but allowing automatics to shift themselves while forcing manuals to conform to some arbitrary standard gives people the idea that autos are more efficient than they really are.

I don't mind the set acceleration cycle. But they should allow for manufacturers to suggest shift points for manuals, with the provision that those suggested shift points are printed somewhere inside the vehicle, like on the visor (some older vehicles without tachometers featured this).

Then feature EPA economy numbers for an acceleration-deceleration cycle, economy numbers in gallons per hour at idle, then economy numbers for steady state cruising at 50 and 70 mph, with a composite number made of the above. This allows various owners to see what kind of economy they'd get in their particular driving environment, much as plug-in drivers can now see mixed economy for their vehicles, with one number for all-electric range and consumption and another for range extension mode.

By showing consumers the difference in consumption between different cruising speeds, you now condition buyers by showing them how much money they will save by driving at a lower cruising speed. Not everyone will respond positively, but it's a start.

That's quite different from what the EPA did with their last revision... where they instead changed numbers to match the higher speeds people actually did.

 

[Sniffs]

and speaking of shift points, that also depends on the driver and how much of a lead foot he/she has. I've punched autos up to 5k, and before Manuals faded into obscurity, here, I was taught that you have to learn to shift "by ear". IE learn WHERE you're supposed to shift by listening for the right point.

unfortunately, by the time I started actually learning how to drive, manuals were confined to small imports and big rigs. no-one is willing to "risk their transmission" nowadays to teach me. cars seem to be turning back into "luxury items" that they were when they were first invented.

 

[Mr. CoolFiat]

One more question:
How have transmissions evolved? I have seen in my Consumer Reviews book that Automatic Transmission in the 80's sucked up your horsepowers? How so?
Why don't manuals do the same? Why don't auto transmissions suck up horsepower nowadays? Or why are they not listed as such, and if they do suck up horsepower... is there a way to measure it?

 

[homeforsummer]

One more question:
How have transmissions evolved? I have seen in my Consumer Reviews book that Automatic Transmission in the 80's sucked up your horsepowers? How so?
Why don't manuals do the same? Why don't auto transmissions suck up horsepower nowadays? Or why are they not listed as such, and if they do suck up horsepower... is there a way to measure it?

Old torque converters in auto transmissions didn't lock up as often as modern ones do. The torque converter absorbs some of the power and torque of an engine to ensure the power that's reaching the road is being delivered as smoothly as possible. You can often tell how little engine power is being used in a slushbox auto by cruising along at a steady speed and flexing your right foot. Often the revs will rise and fall far more than the road speed.

Torque converter lock-up changes this, because when the converter locks then much more of the actual engine power reaches the road, meaning more performance and better fuel efficiency.

Mazda now thinks they can make a torque converter auto that's more efficient than CVT or DSG gearboxes and far more so than older torque converter boxes. The best modern torque converters lock about 60% of the time, Mazda says they're developing one that locks up to 88% of the time. The more power reaching the wheels then the more efficient your progress, which is good for economy too.

Manuals are different because any time you're not disengaging the clutch by pressing the pedal, drive is pretty much direct (well, it still goes engine > gearbox > diff > driveshafts, but the power being transferred is equivalent to the throttle you're using).

 

[Mr. CoolFiat]

Old torque converters in auto transmissions didn't lock up as often as modern ones do. The torque converter absorbs some of the power and torque of an engine to ensure the power that's reaching the road is being delivered as smoothly as possible. You can often tell how little engine power is being used in a slushbox auto by cruising along at a steady speed and flexing your right foot. Often the revs will rise and fall far more than the road speed.

Torque converter lock-up changes this, because when the converter locks then much more of the actual engine power reaches the road, meaning more performance and better fuel efficiency.

Mazda now thinks they can make a torque converter auto that's more efficient than CVT or DSG gearboxes and far more so than older torque converter boxes. The best modern torque converters lock about 60% of the time, Mazda says they're developing one that locks up to 88% of the time. The more power reaching the wheels then the more efficient your progress, which is good for economy too.

Manuals are different because any time you're not disengaging the clutch by pressing the pedal, drive is pretty much direct (well, it still goes engine > gearbox > diff > driveshafts, but the power being transferred is equivalent to the throttle you're using).

Thank you for the information. But I want some more input from other users. Thank you for the time.

 

[Tornado]

I'm not sure what more there is to tell. homeforsummer about covered it.




The only thing I can add is that cars with slushboxes occasionally get better mileage than cars with sticks because the engine computer/transmission can be programmed to work in harmony in a way that can't be replicated with a manual (and its easier to implement things like cylinder deactivation on automatic transmission cars). How often that actually happens is a completely different matter, but that's the theory anyways.

 

[niky]

Modern torque converters definitely lock-up more, and in higher gears, are often programmed to lock up earlier.

Early lock-up in low gears is often problematic. In first gear, the torque converter's slipping action simulates "slipping the clutch", which we do in manuals to ensure smooth take-off from the lights. This was a problem with early SMG and DCT boxes (and some current ones), as without torque converters, take-off would be abrupt, and the difference between coast-down engine braking and full decoupling is also abrupt.

With an old AT, the "stall speed", the speed at which the TC would stop slipping and the drive would engage directly, was constant. Most boxes stall around 2500-3000 rpm. Great for good take-off, terrible for cruising at 3000 rpm at 60 mph. New boxes can stall at 3000 rpm for smooth take off, then lock up in 5th or 6th gear at 1500 rpm or lower so you can cruise in 5th or 6th with no loss of drive.

It's wonderful stuff. Manuals still have less loss overall, since they're still not pushing fluid around inside the pumpkin. But as compared to old ATs, these new ones are stellar.

 

[CSLACR]

Most Corvette owners unplug the solenoid for the "skip shift".

Obviously you don't give manufacturers free reign... but allowing automatics to shift themselves while forcing manuals to conform to some arbitrary standard gives people the idea that autos are more efficient than they really are.

I don't mind the set acceleration cycle. But they should allow for manufacturers to suggest shift points for manuals, with the provision that those suggested shift points are printed somewhere inside the vehicle, like on the visor (some older vehicles without tachometers featured this).

Then feature EPA economy numbers for an acceleration-deceleration cycle, economy numbers in gallons per hour at idle, then economy numbers for steady state cruising at 50 and 70 mph, with a composite number made of the above. This allows various owners to see what kind of economy they'd get in their particular driving environment, much as plug-in drivers can now see mixed economy for their vehicles, with one number for all-electric range and consumption and another for range extension mode.

By showing consumers the difference in consumption between different cruising speeds, you now condition buyers by showing them how much money they will save by driving at a lower cruising speed. Not everyone will respond positively, but it's a start.

That's quite different from what the EPA did with their last revision... where they instead changed numbers to match the higher speeds people actually did.

Well those are good ideas, there are two problems I see though, firstly being overly complicated, we have to remember how the higher percentage of people view and process the information, and while could be very beneficial, it might not be as effective as it should be in theory.
Aside from that, the problem with encouraging people to slow down, is cars have different fuel efficiency speeds, so while the guy that's willing to drive 50mph to get optimal fuel efficiency in his Focus wants to go 50mph, he'll pretty much be screwing the guy behind him over who gets his optimal efficiency at 60mph. We already have this problem somewhat, and Prius owners show most of this on a daily basis, it's better to program cars to be efficient at similar speeds rather than maximize each for it's own potential. Also, as I said before, it takes a long time to get places at 50mph (or less) then 70 mph, which can be a big issue in the U.S., not everyone can get a decent job within 10 miles of their house, I've personally driven up to 55 miles each way to work, 5 times a week, so we're talking literally hours a week extra driving time, so I'd rather have a car as efficient as possible at 70mph than a car designed for 50mph.
I guess the short version is slowing everyone down 20mph would certainly cause some economical issues for people in these spread out states.

Modern torque converters definitely lock-up more, and in higher gears, are often programmed to lock up earlier.

Early lock-up in low gears is often problematic. In first gear, the torque converter's slipping action simulates "slipping the clutch", which we do in manuals to ensure smooth take-off from the lights. This was a problem with early SMG and DCT boxes (and some current ones), as without torque converters, take-off would be abrupt, and the difference between coast-down engine braking and full decoupling is also abrupt.

With an old AT, the "stall speed", the speed at which the TC would stop slipping and the drive would engage directly, was constant. Most boxes stall around 2500-3000 rpm. Great for good take-off, terrible for cruising at 3000 rpm at 60 mph. New boxes can stall at 3000 rpm for smooth take off, then lock up in 5th or 6th gear at 1500 rpm or lower so you can cruise in 5th or 6th with no loss of drive.

It's wonderful stuff. Manuals still have less loss overall, since they're still not pushing fluid around inside the pumpkin. But as compared to old ATs, these new ones are stellar.

If I'm not mistaken manuals also have less rotating mass than automatics.
Never could understand the high demand for cars with less effective power, fuel efficiency, higher upfront cost, and maintenance costs...(AT)
Worst case scenario is a torque converter like mine, revving a pushrod V6 to 3500 rpm before quitting.

 

[niky]

The thing is... all cars are more efficient at 50. Some could be more efficient if they were geared for it, but you can't change the fact that air drag is always worse at higher speeds.

-

What I envision is a color-coded infographic. Numbers confuse people, but an infographic showing fuel consumption in bars (5 mpg per bar) with only four fields would be very easy to understand.

 

[BrutherSuperior]

The thing is... all cars are more efficient at 50. Some could be more efficient if they were geared for it, but you can't change the fact that air drag is always worse at higher speeds.

That's not entirely true.

In practice, most cars will see max efficiency around 65. Past that, drag takes to much of a toll and puts a greater load on the engine. The reason for the 65MPH number really comes down to gearing and where most engines are efficient in the rev range.

50MPH may be even be more efficient if you downshifted a gear.

At higher RPMs, your garden variety DOHC engine will achieve better fuel atomization than at lower RPMs. Unfortunately, you cannot take gearing out of the mix...unless you rock a CVT.

With a CVT, then you're balancing overall speed vs. aerodynamic drag. 50mph may be more efficient...may not be. I've never owned a CVT or driven one with the sole purpose to monitor fuel consumption. That'd be a neat experiment though.

 

[CSLACR]

The thing is... all cars are more efficient at 50. Some could be more efficient if they were geared for it, but you can't change the fact that air drag is always worse at higher speeds.

-

What I envision is a color-coded infographic. Numbers confuse people, but an infographic showing fuel consumption in bars (5 mpg per bar) with only four fields would be very easy to understand.

Well you certainly can't be saying the best economy speed for a Corvette is the same as a small box like a Scion Xb...
Higher weight means momentum from speed helps, good airflow means speed doesn't counter momentum as much, etc.

I personally don't have any statistics on what a Corvette "could" achieve at 50mph, nor most vehicles, but basic physics tell me there will be significant differences vehicle type to vehicle type.
I know a lot of smaller lighter cars would peak around 40mph, but then I wouldn't expect someone living in a tighter community to understand a need for higher speeds.
The notion that we should putter around between 40-50mph down highways and just "move or change jobs" seems pretty ignorant of the U.S. layout. That or completely inconsiderate of people's lives, I'm sure you don't want your drive times increased 25% or more, even without a two hour daily commute. In America we have to drive much further to get places on a regular basis than most if not all countries.

To me the best solution is making cars more efficient at higher speeds.

Also, the fact remains with an EPA highway test the Civic from 18 years ago managed 55 mpg at speed of 55mph, and then was corrected for at least 65mph and still maintained 50mpg. And that's a car not designed or geared to achieve maximum economy at 65mph.

We're nowhere near out of oil, other methods are coming into play, and the current level of emissions from new cars is jack diddly, so I don't see the problem with higher speed driving, aside from price gouging of fuel, which is simply advantage being taken.

 

[niky]

Estimated to make 50 mpg. Not tested to. There's a difference. Not saying that it couldn't, but since nobody has a stock, brand new one to put through the EPA test cycle (which, mind you, is not the same as actually driving on the highway), we'll never know now, will we?

That's not entirely true.

In practice, most cars will see max efficiency around 65. Past that, drag takes to much of a toll and puts a greater load on the engine. The reason for the 65MPH number really comes down to gearing and where most engines are efficient in the rev range.

50MPH may be even be more efficient if you downshifted a gear.

50 mph is not ideal for everyone... but slower is often better... especially if your car has enough torque to pull in gear at that speed.

Wanna take bets on Vettes?

http://ecomodder.com/forum/showthread.php/tested-speed-vs-mpg-2008-corvette-z06-505-a-9841.html

I love Eco-modder... some really freakish DIY projects to do there...

While Scangauges are not 100% accurate for showing car-to-car numbers, at least in steady-state cruising as in this test, it's good enough to show percentage differences. And they're big.

Now, see... if EPA stickers were a graph like this... what would you bet that more people would drive slower? "My Vette can hit almost 40 mpg as long as I don't have to accelerate!"

I've driven a lot of Eco-Runs and witnessed others. I've personally gotten cars past the magic 80 mpg mark. Sweet spot really is 45-50 mph for most cars... some smaller engined cars need to be one gear lower at 40 mph and below... and lower than 50 is illegal on some roads.

*Disclaimer... if you're driving slower than the flow of traffic, stay as far right as possible and let people through. No one likes an ass who blocks the road driving 10-20 under the limit!

Problem with some ATs, though, is that you can't lock them one gear lower so you can cruise at 50 mph unless you have a +/- mode or paddle shifters that allow you to lock in gear... though with lots of torque this isn't a big problem.

 

[homeforsummer]

The only thing I can add is that cars with slushboxes occasionally get better mileage than cars with sticks because the engine computer/transmission can be programmed to work in harmony in a way that can't be replicated with a manual (and its easier to implement things like cylinder deactivation on automatic transmission cars). How often that actually happens is a completely different matter, but that's the theory anyways.

Not to mention that slushboxes probably get better mileage than a lot of manual trans vehicles simply because some people are so awful at using a manual transmission, that even a less efficient auto will get them better MPG numbers and probably performance numbers too.

As far as cylinder activation systems go makes for an interesting point - I know that on the original Honda Insight, only the manual transmission vehicle had lean burn technology. Part of the reason for this was that in the CVT transmission where the revs rise and fall independently of road speed the system would constantly be switching on and off as revs rose and fell. The system was more stable with manual transmission.

The other reason the CVT didn't have lean burn was that lean burn produces more NOx, and offering a model without it in the USA meant the Insight gained Super-Ultra Low Emissions Vehicle status for all sorts of tax breaks etc.

That's not entirely true.

In practice, most cars will see max efficiency around 65. Past that, drag takes to much of a toll and puts a greater load on the engine. The reason for the 65MPH number really comes down to gearing and where most engines are efficient in the rev range.

Cars are at their most efficient in as high a gear and low a revs as possible without needing to change down, i.e. able to provide efficient acceleration without labouring the engine - so as you say, that's basically down to gearing.

For some cars this can be as little as 40mph, others may be as much as 70mph odd.

That aside, the two main handles on efficiency are aerodynamics and engine friction. Aero drag increases with the square of speed and for most cars this exponential increase means that aero drag really starts affecting MPG from around 40mph onwards unless you're driving something really aerodynamic.

Engine friction in any vehicle also starts increasing exponentially after about 2000-2500rpm, which means that for the majority of vehicles, cruising below this engine speed will give far greater gains in MPG than cruising above it - with the caveat that if you need to accelerate, some cars might reduce in efficiency if there isn't enough torque at these engine speeds for acceleration. For cruising on a completely flat road though at a constant speed, efficiency will always be greater below that engine speed.

*Disclaimer... if you're driving slower than the flow of traffic, stay as far right as possible and let people through. No one likes an ass who blocks the road driving 10-20 under the limit!

Quite. Eco driving is a challenging skill and can even be quite fun because of this, but I've never been keen on true hypermiling as it presents too many opportunities to cause a nuisance to everyone else on the road.

 

[CSLACR]

Estimated to make 50 mpg. Not tested to. There's a difference. Not saying that it couldn't, but since nobody has a stock, brand new one to put through the EPA test cycle (which, mind you, is not the same as actually driving on the highway), we'll never know now, will we?



50 mph is not ideal for everyone... but slower is often better... especially if your car has enough torque to pull in gear at that speed.

Wanna take bets on Vettes?

http://ecomodder.com/forum/showthread.php/tested-speed-vs-mpg-2008-corvette-z06-505-a-9841.html

I love Eco-modder... some really freakish DIY projects to do there...

While Scangauges are not 100% accurate for showing car-to-car numbers, at least in steady-state cruising as in this test, it's good enough to show percentage differences. And they're big.

Now, see... if EPA stickers were a graph like this... what would you bet that more people would drive slower? "My Vette can hit almost 40 mpg as long as I don't have to accelerate!"

I've driven a lot of Eco-Runs and witnessed others. I've personally gotten cars past the magic 80 mpg mark. Sweet spot really is 45-50 mph for most cars... some smaller engined cars need to be one gear lower at 40 mph and below... and lower than 50 is illegal on some roads.

*Disclaimer... if you're driving slower than the flow of traffic, stay as far right as possible and let people through. No one likes an ass who blocks the road driving 10-20 under the limit!

Problem with some ATs, though, is that you can't lock them one gear lower so you can cruise at 50 mph unless you have a +/- mode or paddle shifters that allow you to lock in gear... though with lots of torque this isn't a big problem.

Okay, so by your own graph 50mph is not optimal for all cars. In fact, 100mph is more effective for the Corvette than 50mph.

Estimated to make 50 mpg. Not tested to. There's a difference. Not saying that it couldn't, but since nobody has a stock, brand new one to put through the EPA test cycle (which, mind you, is not the same as actually driving on the highway), we'll never know now, will we?

Okay, so if word is good enough for different achieved real-world driving mpg rates, we can check what Civic owners report, yes?
And speculation about how "maybe it couldn't, etc" is fine, it's not realistic, and I think you know this already, so why the semantics?
On one hand you question EPA methods, and on the other, it sounds like a brand new EPA test is the only thing you'll consider accurate.

Fact is, at 55mph it already did test at 56mpg. If you want to speculate what 10mph will do to it's economy, arguing with professional calculations, you're allowed to, but it doesn't make you right.

 

[homeforsummer]

Okay, so by your own graph 50mph is not optimal for all cars. In fact, 100mph is more effective for the Corvette than 50mph.

How'd you work that one out? The numbers you're looking at are kilometres... In which case, 100km/h (60 ish mph) is quite obviously going to be more economical than 50km/h (30 ish mph) because at 30mph the Vette is well out of the usable torque band and it ends up labouring in 5th gear (fuel efficiency would more than likely improve at 30mph by dropping another gear, as BrutherSuperior suggested earlier), whilst doing half the speed it would be doing at 60mph so it's not covering as much ground for all that fuel being used either.

At 100mph you'll probably be looking at 15mpg or less, judging by the way that graph is heading. At 50mph it's getting over 30mpg, which isn't that bad. Over twice the MPG that 100mph would likely provide, in fact. Almost certainly significantly more than twice that MPG, since you'd soon start getting into the rapidly increasing spiral of engine friction, as well as exponential aero drag.