EcoModder.com

EcoModder.com (https://ecomodder.com/forum/)
-   The Lounge (https://ecomodder.com/forum/lounge.html)
-   -   Reality check: 3% of U.S. interviewees know what a "start/stop" system does (https://ecomodder.com/forum/showthread.php/reality-check-3-u-s-interviewees-know-what-21988.html)

MetroMPG 05-21-2012 12:16 PM

Reality check: 3% of U.S. interviewees know what a "start/stop" system does
 
Sometimes it's useful to be reminded that when it comes to things automotive, our reality is very different from the average person's.

Today's reminder:

Quote:

Consumer research by Johnson Controls [...] found there's little consumer awareness of the technology that shuts off a car's engine when the brake pedal is depressed. Only three out of 100 people interviewed during focus groups this year knew about start-stop technology
Johnson Controls battery halts idling, saves fuel - JSOnline

gone-ot 05-21-2012 12:21 PM

START & STOP - isn't that what *happens* when a rookie attempts to drive a manual transmission for the first time (wink,wink).

ecomodded 05-21-2012 12:34 PM

like me with my hydrogen car knowledge, more precisely lack of it. Bear with me as i trudge along learning as i go.
Funny though I know more about feul economy/ new technology then anyone i personally know, yet i am a beginner at it on this site..

Piwoslaw 05-21-2012 03:50 PM

I'm sure that more than 3% of US interviewees know what 'horsepower' is, or at least can tell you that "more is better". :rolleyes:

If among those who don't know what start&stop is are owners of vehicles with that function, then that means that the system works well enough to not be noticible by the user, which is what car companies are aiming for.

jamesqf 05-22-2012 12:12 AM

I wouldn't know either, if you called it that. It's autostop, at least to anyone who's owned a Honda hybrid, and I think Toyota too.

drmiller100 05-22-2012 10:26 AM

how many people think "torque" is what accelerates a car???

ecomodded 05-22-2012 11:09 AM

I'll bite, I think torque is what accelerates my car.
It would make sense also if you said horsepower is what accelerates the car but in my mind its the torque that gives it the pull.

Flakbadger 05-22-2012 11:13 AM

Quote:

Originally Posted by ecomodded (Post 308464)
I'll bite, I think torque is what accelerates my car.
It would make sense also if you said horsepower is what accelerates the car but in my mind its the torque that gives it the pull.

It's my understanding that torque is your 0-60 MPH time, and horsepower is your 60-120 MPH... IE why Semi trucks have 500 HP and 1,500 lb/ft torque. Semi trucks aren't necessarily going to win any 0-60 contests because they're not geared for it, but still.

niky 05-22-2012 11:33 PM

Torque doesn't accelerate your car. Wheel torque does. And the maximum wheel torque you can put down at any road speed is a function of gearing, torque and rpm. And what do we derive from torque and rpm? Horsepower.

The reason people say that "Horsepower sells cars, Torque wins races" is that peak horsepower is a meaningless figure... because your car is not at peak horsepower at all times.

Instead, 0-60 mph is determined by how much average horsepower you can put down in each gear going up to 60 mph. Average horsepower which must be calculated from dyno readouts, but which can be estimated by looking at peak torque and peak horsepower together.

-----

While it's true a car accelerates faster at torque peak than horsepower peak (assuming the two are separate), two cars with the same peak torque figures will not accelerate the same if one makes peak torque at a lower rpm. Why? Because the car making peak torque at a higher rpm is making more horsepower, and can use torque multiplication more effectively than the lower-revving car.

-----

I'd go further and talk about the additional torque multiplication of smaller tires, the effects of drivetrain loss and tire slip, and aerodynamics... but since tire size has a relatively minor effect compared to gears, tire slip is variable dependent on condition, drivetrain loss is a whole bunch of fudged-up estimation and the equations for aero drive me batty... I won't. :D

ksa8907 05-22-2012 11:43 PM

Torque is a more useful measure. Honestly, how often do you hit redline in your car? Most engines make peak power at redline.

niky 05-22-2012 11:52 PM

Torque by itself is meaningless.

A vehicle that has 300 ft-lbs of torque will always be quick... ish... but a vehicle that has 300 ft-lbs of torque at 2000 rpm is never going to be as quick past the first 30 km/h as one that makes 300 ft-lbs at 4000 rpm. Why? Because the car making 300 at 2000 is only making 114 hp, while the car making 300 at 4000 is making 228 hp... at 4000 rpm... and is most likely making 300 horsepower at 6000, whereas the car making 300 at 2000 is usually making 150-ish horsepower at 3500 rpm.

Torque is useful... but again, taking into account only peak torque or peak horsepower is very misleading.

gone-ot 05-23-2012 09:49 AM

Power is 'how often/fast" the torque is produced.

ecomodded 05-23-2012 12:04 PM

Torque down low in the rpm's is more useful and economical. A semi trailer truck is the perfect analogy of max torque benefit over the max hp rating.
Good info in your post niky.

tortoise 05-23-2012 01:15 PM

Quote:

Originally Posted by niky (Post 308559)
. . . a car accelerates faster at torque peak than horsepower peak

A car accelerates fastest (at any given road speed) with greatest torque at the wheels, which will be provided by putting it in a gear that puts the engine at peak horsepower. Do the math (or listen to a drag race).

Horsepower and torque are numerically equal at 5252 RPM.

niky 05-24-2012 05:35 AM

I don't disagree with you, but I didn't mean what you thought I meant. I simply meant that peak transient acceleration occurs at peak torque in the lowest gear a vehicle has, and acceleration tapers off past peak torque.

Yes, you keep it there because that gives you the best torque multiplication... except in the case of some diesels where torque tapers off greatly as they approach redline.

I have done the math. I even built a wheel torque calculator from scratch for use with video game programming. I had to brush up on my math to update it to take into account wheel sizes, since I can't tell a radian from a median. I had to do that because wheel size actually makes a sizeable difference in the results I'm publishing for an upcoming article given the low power output of the engines I was graphing.

Still working on graphing wheel torque against drivetrain drag, aero drag and rolling resistance, but the fudge factors are so big that classical equations given by the textbooks are almost useless without adding in a whole lot of correction factors... :(

markweatherill 05-24-2012 09:05 AM

I would say that I don't know about start/stop systems but I do know about stop/start ones. ie I think that is how most manufacturers describe them.

jason1973tl 05-24-2012 01:15 PM

I have also heard it said that if you want better fuel economy you build your car for torque. But anyways unless you are planning on making all cars hybrids I think autostop is just going to add more needless complications to our cars. They are already too complicated the way it is.

tortoise 05-24-2012 01:41 PM

Quote:

Originally Posted by niky (Post 308742)
I don't disagree with you, but I didn't mean what you thought I meant. I simply meant that peak transient acceleration occurs at peak torque in the lowest gear a vehicle has, and acceleration tapers off past peak torque.

We are in full agreement. You can't shift down from first gear. Excuse me for misunderestimating you. The error I thought you made is not uncommon.

Daox 05-24-2012 01:43 PM

Autostop doesn't actually add complexity to cars. Its just a little additional programming in the ECU, a beefier starter, and a beefier battery, thats it.

tortoise 05-24-2012 01:51 PM

Quote:

Originally Posted by Daox (Post 308815)
Autostop doesn't actually add complexity to cars. Its just a little additional programming in the ECU, a beefier starter, and a beefier battery, thats it.

Do some start/stop systems use a starter/alternator, actually mechanically simplifying things?

cfg83 05-24-2012 02:25 PM

Daox -

Quote:

Originally Posted by Daox (Post 308815)
Autostop doesn't actually add complexity to cars. Its just a little additional programming in the ECU, a beefier starter, and a beefier battery, thats it.

Which increases UMC (Unit Manufacturing Cost) :

Quote:

For a $295 premium, the new battery technology can deliver fuel economy saving of 3.5% to 10%, according to Ford.
Mazda has the i-stop :

MAZDA:Idling stop technology | Environmental Technology
Quote:

Idle stop systems save fuel by shutting down a vehicle's engine automatically when the car is stationary and restarting it when the driver resumes driving. Especially in urban areas, drivers often let their car's engine idle at traffic lights or when stopped in traffic jams. Switching off the engine to stop it idling in these situations enhances fuel economy by about 10% under Japan's 10-15 mode tests*1.
From what I understand Mazda *didn't* bring their autostop tech to the USA because the benefit isn't quantified in the EPA MPG test. No carrot, no incentive to increase UMC. But maybe that's changed?!?!?!?!?

Even though it's a simple idea, I wouldn't expect people to know about it. It's also got "complicated" states that could disable it, aka is the A/C on, is the battery low, blah blah blah.

CarloSW2

Daox 05-24-2012 02:33 PM

I understand it increases cost. I was just speaking to the comment about complexity. The only thing thats really anymore complex is the ECU programming which one usually doesn't ever need to mess with. You might even argue that its LESS complex due to having a beefier starter that is designed for many more starting cycles and may not ever need to be replaced.

cfg83 05-24-2012 02:33 PM

jamesqf -

Quote:

Originally Posted by jamesqf (Post 308416)
I wouldn't know either, if you called it that. It's autostop, at least to anyone who's owned a Honda hybrid, and I think Toyota too.

I agree. I also think autostop has been denigrated as being a feature of mild-hybrids.

I have a question. You have the 1st-gen manual Insight. That has autostop. Can you explain how it restarts the car? Is it based on depressing the clutch or ???

CarloSW2

gone-ot 05-24-2012 02:35 PM

...it (auto/idle stop) is now being used to help bolster each manufacturer's CAFE numbers in effort to meet the EPA's "new" higher-MPG requirements.

jamesqf 05-25-2012 12:13 AM

Quote:

Originally Posted by cfg83 (Post 308831)
I have a question. You have the 1st-gen manual Insight. That has autostop. Can you explain how it restarts the car? Is it based on depressing the clutch or ???

You know, that's kind of like asking me to explain how to ride a bicycle. It's just automatic :-)

As I think about it, it's not the clutch, or not entirely. It will autostop with the clutch pressed and the transmission in gear, and start again when I let out the clutch & step on the gas, but I'm not sure which does it. It'll also autostop if the clutch is out and the transmission is in neutral, and start again when I press clutch & shift into gear, but I don't really know if it's the shifting or the clutch that triggers it.

Edit: I forgot about the brake. You generally have to be stepping on the brake for autostop to happen, and letting off will (often/always? - as I said, I don't really think about it any more) cause the engine to restart.

niky 05-25-2012 04:02 AM

I think Mazda didn't bother because the EPA gain doesn't reflect the full potential of the system enough to warrant increasing unit costs... which makes sense when you're trying to sell cheap cars. (Don't ask me why they thought the expensive SkyActiv engines were worth it!)

I think most of us here already recognize the limitations of EPA test numbers... but the general public will see the relatively tiny EPA gain Mazda would've gotten with the system as some sort of proof of its worthlessness.

Perhaps newer systems with more powerful starter motors that also give a mild assist will make more of a difference.


All times are GMT -4. The time now is 01:11 PM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2022, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com