Toyota rep at Frankfurt IAA said FT-86 weight will be 1,160kg (2,555 pounds)

[ichitaka05]

^"How you drive change MPG & not, what you drive" pretty much, right?

[serialk11r]

That's because in the past, small displacement engines were geared retardedly short. I personally don't know why Honda wanted so much specific torque out of these small engines, after a point it directly contributes to lower efficiency. That said, these 2 liter engines have much more fuel economy potential than the larger engines you described. The larger engines are geared to turn under 2000 rpm on the highway while as we said, the s2k can hit over 4000. If you compare the amount of air the engine is breathing, it's apparent the small engine has even more pumping loss because the gears are so short.

As of now, small displacement engines have an advantage that hasn't been tapped. In the future as engines get more advanced the fuel efficiency advantage will become smaller...

By the way, I'm pretty sure a Civic Si typically gets much much much better fuel economy than any 3.8L V6. I've looked online before, these big engines that have high EPA ratings usually get less mpg in the real world, and the small engines with seemingly bad ratings usually get more

Point is, it's COMPLETELY wrong to say higher displacement, less rev = more fuel economy...all else being equal, at the end of the day larger engines have more losses across the board simply by being bigger. Especially in city driving, you don't need more than a tiny fraction of all that displacement to move around, so the rest serves to waste more fuel.

[CyberFormula]

Originally Posted by old greg

Hell, even back then the story wasn't much different. Folks who drove their Hondas "enthusiastically" would get worse gas mileage than people with Mustang GT's driving at equal speeds/accelerations.

I will let Jeremy Clarkson illustrate this further.
[u2b]_JdOH7GrE6Q[/u2b]

this is stupid.

if mustang drive as slow as the prius, prius will get better gas mileage.
if prius drives as fast as mustang, mustang will get better gas mileage....COMPARED to the prius.

What does that mean?
That means mustang gets bad mileage going fast or slow. Prius only gets bad mileage when you floor it.

[tranzformer]

Originally Posted by ichitaka05

^"How you drive change MPG & not, what you drive" pretty much, right?

To a point. A Veyron cursing at 65mph on the highway won't be more economical than a Golf TDI cursing at 65.

[ichitaka05]

Originally Posted by tranzformer

To a point. A Veyron cursing at 65mph on the highway won't be more economical than a Golf TDI cursing at 65.

Touche sir

[serialk11r]

Actually I'd say, that statement is completely false. On a normal road you are not turning corners constantly, you spend most of the time going straight. You don't press the brake super hard, you can cruise to a stop.

Cruising fuel economy cannot be improved, it is something linked to the engine design and gearing. You cannot coax more efficiency out of a car with your foot. During city driving in particular a large displacement engine has more engine braking and idle consumption, there is nothing you can do to remedy that besides cruising in neutral with the engine off at all times when you aren't accelerating.

The one thing about what Jeremy Clarkson said that's true is switching a car probably costs more than what you'll save in fuel, so do what you can to improve fuel economy. Most people on the road that I see at least seem to be in a huge rush and drive pretty aggressively, using the brakes a lot because they're weaving through people too much. That can be corrected. Another thing is people who step on the gas even though there's a red light waiting for them. Or accelerating into a turn then braking at the last moment.

[tranzformer]

Originally Posted by ichitaka05

Touche sir

[Deslock]

Originally Posted by madfast

there's no reason you cant, but there's also no reason why you should have to...

THAT'S where the complaints come in. the car forces you to rev higher and the shorter gearing forces you to shift more often. can you rev all the way to redline? can you downshift to pass? of course! but in other cars you dont necessarily have to. and so the criticism is valid.

I never claimed the criticisms aren't valid, but no one is forced to drive these cars... there are plenty of options out there for people who just want to mash the pedal and go. The S2k and FT are for those of us that [1] enjoy running through the gears with a short throw and [2] prioritize the advantages of a small N/A engine over the disadvantages.

Originally Posted by madfast

it must be said again, gearing CANNOT replace engine torque.

In some applications, gearing cannot replace torque, while other times torque cannot replace gearing. In general, extra engine torque is preferable because it's convenient and provides more flexibility.

Originally Posted by SUB-FT86

A civic Si gets 29 mpg on the highway. A GC 3.8 liter gets 26 mpg on the highway. A 3.7 Mustang gets 31 mpg on the highway. I dont see a major difference in this day and age and the sad part is the coupes I mentioned weigh 550+ lbs heavier than the Si with the k20. This isnt 1998. A high revving 2.0 liter is shitty on gas too. And also those coupes use regular gas.

Both the Civic Si and Mustang V6 get 31 MPG highway. Though the Mustang deserves a lot of credit for delivering that fuel efficiency along with 300 HP, to me highway MPG is meaningless. The Mustang gets an unimpressive 19 in the urban cycle. Sport compacts are tuned for throttle response and output rather than fuel economy, so the Civic isn't that great either at 22.

Also, my experience matches up with what serialk11r wrote: cars like the Civic Si typically exceed their ratings in real world use while cars like the Mustang do not. YMMV (literally).

Originally Posted by old greg

I will let Jeremy Clarkson illustrate this further.
[u2b]_JdOH7GrE6Q[/u2b]

That episode was amusing like always. It was also misleading... all it really showed was that a flogged econobox can get poorer MPG than a performance car that's driven leisurely (as the M3 was with its grippier tires, better chassis, better suspension, and much more powerful motor).

[Dave-ROR]

Originally Posted by madfast

but at what cost? in theory world yes, but what about in $5 a gallon reality...?

and if anybody wants to pull the we enthusiasts dont give a crap about mpg you gotta pay to play BS, then what about wear and tear of high rpm? the higher cost to make the engine reliable at high rpm? etc etc etc ad nauseam. nothing is free, you will have to compromise elsewhere.

Again on three if my cars I have 218k+160+130 so around 510k on high rpm engines unopened (the 218k one is being rebuilt after 5k of wheel to wheel racing miles though still runs great and places well though).

So IMO gearing can replace torque to a point. MPG? I get mid to high 30s on the cars except for the race car which averages about 10 (8-12 depending on the track) but a mustang racing gets 4-5...

The compromise for many is the need for lightweight carsbwith low torque engines and that means limited luxury, sound deadening, etc. That's just fine with me.

[old greg]

Originally Posted by Deslock

all it really showed was that a flogged econobox can get poorer MPG than a performance car that's driven leisurely.

What it showed is that if you are going to drive enthusiastically, short shifting a larger torquier engine will get you equal performance and comparable or better fuel consumption than you'll get from winding out a small four banger. Why? because BSFC worsens significantly at high rpm on production cars. But, a larger engine can produce an equal area under the power curve (= energy = change in velocity) with lower rpm and/or less throttle, operating closer to it's best BSFC.

[Deslock]

Originally Posted by old greg

What it showed is that if you are going to drive enthusiastically, short shifting a larger torquier engine will get you equal performance and comparable or better fuel consumption than you'll get from winding out a small four banger.

The M3 was not driven enthusiastically ("It was one of the dullest drives of my life" - Clarkson). Ironically, that Top Gear clip underscores one of the points some of us have been making: Even an M3 is boring when it can't be pushed (which you can't at remotely close to legal speeds on most public roads in the USA).

Having written all that, I agree that "short shifting a larger torquier engine" *can* "get you equal performance and comparable or better fuel consumption than you'll get from winding out a small four banger".

Originally Posted by old greg

BSFC worsens significantly at high rpm on production cars. But, a larger engine can produce an equal area under the power curve (= energy = change in velocity) with lower rpm and/or less throttle, operating closer to it's best BSFC.

That's true, but if that M3 had run at WOT, it wouldn't have achieved 19 MPG (even if it was kept at low RPMs). It would've gone around the track faster than the Prius though.

[Spaceywilly]

Originally Posted by Deslock

The M3 was not driven enthusiastically ("It was one of the dullest drives of my life" - Clarkson). Ironically, that Top Gear clip underscores one of the points some of us have been making: Even an M3 is boring when it can't be pushed (which you can't at remotely close to legal speeds on most public roads in the USA).
.

Yep. I would say the Prius driver was having more fun in that video, and they still are able to get 60mpg when they aren't driving around the top gear track. The M3 on the other hand could be tons of fun on the Top Gear tack, but on regular roads you won't be pushing it unless you have a death wish and you'll still only get 19mpg. I think something like a miata or ft86 gives you the best of both worlds. You'll be driving closer to its limits on fun backroad/canyon runs without endangering anyone's life, you can still flog it at the track, and it should have decent highway mpg. The M3 and basically all high-end German cars are designed for the Autobahn where you can really use its capabilities on a regular basis, and it is designed for people who wipe their ass with hundred dollar bills so they don't really care how much gas it uses. Unfortunately I am not one of those people.

I think the BSFC argument is irrelevant because 99% of the time you aren't going to be wringing out the engine. Maybe a bigger displacement engine that you can short shift will get better fuel economy under heavy acceleration, but what percentage of time do you spend doing that? Most of the time driving for most people is spent cruising on the highway, in which case those extra cylinders are just wasting gas.

[serialk11r]

@old greg

BFSC under full throttle? I don't think people floor the gas when accelerating normally.

Also if you look closely at the scale, you'll see efficiency doesn't actually drop that much at higher rpm. Let's talk a little basic physics, I need a break from studying:

As rpm increases:
1. Friction loss from gears, piston ring/sidewall contact, is approximately constant.
2. Pumping loss increases at WOT, but this is superceded by the gains from 3.
3. "blowdown loss" (more charge in the cylinder, the more of it is wasted due to the expansion stroke not being long enough) decreases after a point because the intake system restriction becomes somewhat significant. With variable valve lift and timing this efficiency "increase" usually comes near the redline though, because the manufacturer wants to have as much max. power as possible. If you look at a typical BSFC chart, the best efficiency comes at about 75% max torque for an engine with a throttle plate. This is to say, filling the cylinder with too much air and fuel wastes more energy than directly giving up useful work to choke off some of that air supply. At higher rpm the maximum efficiency range moves up relative to max torque because of point 2.
4. Frictional loss in bearings around reciprocating parts (and other parasitic losses due to the vibration of the engine) increases as the square of engine speed. This is a somewhat big reason for decreased efficiency at higher rpm.
5. "relative ignition retardation loss" (I made up that term). I am referring to the fact that fuel burns relatively "slower" compared with piston movement as the engine speed increases. The rate that air/fuel mix burns in the cylinder doesn't increase as engine speed increases, but each stroke has less time to happen. Because of this we have to advance spark timing, but igniting the mix earlier and earlier causes the compression stroke to use more power to push against higher pressures for longer. I doubt this loss is that large because Formula 1 engines that run at ridiculous speeds still manage to run very efficiently by gasoline engine standards, although they have the advantage of higher compression, better balance and more advanced materials to reduce losses in other places. In a nutshell, thermodynamic cycle "improvements" don't see as much benefit as you'd think because energy is disappearing in larger quantities in so many other places.
5. Exhaust backpressure increases as the engine breathes air at a faster rate. Again this isn't a very big loss because compared to the other places energy is going, this is usually pretty small.

here is a chart that tells the full story: http://www.pattakon.com/tempman/Saturn_BSFC.gif
As you can see, at the rev limit we are still within about 70% of maximum efficiency at full throttle. This is extremely good, considering that typically cruising along a highway runs your engine at less than 50% efficiency. Of course you have to take into account that manufacturers like to tune higher rpms for additional power output, which can be seen by the torque "jump" in the Honda F20C power chart, which represents a more aggressive and less efficient cam profile. I'm not saying revving high is good for fuel economy, it's clearly not, it's just not nearly as bad as what people make it out to be.

[SUB-FT86]

If you push any car to its limits on the road especially a car that goes to 60 in under 8 seconds. It's not legally possible. If I jump in a miata right now and floor it everywhere I would look like a complete ass with no common sense. If that's what you guys meant then I hope you guys get your shit together and not kill innocent people with your stupid ways. The only cars that makes sense to be pushed to that limit is a city car since they go from 0-60 in 11-13 seconds and make 80-95hp in a 2200 lb body. It would be hard to surpass the speed limit in those cars.





I have revved certain cars no higher than 4500 rpms and I love it(VQ35HR). Why? Because they made actual power where it matters most.