Motortrend smart roadtrip LA to Detroit reports

[jonnysan]

Originally Posted by Willy

I'm not sure I understand... can someone enlighten me as to what this start/stop feature is???

Thanks

When the car comes to a stop such as at a traffic light or stop sign (there must be a short delay on the speedo sensor that tells the ECU it's time to turn off the engine) the engine turns off to conserve fuel and the vehicle's energy needs are supplied by the battery(s). As soon as you start to move again, the speed sensor (or brake light sensor) tells the starter-generator on the serpentine belt plane to restart the engine and it does so. I would think that those starts and stops would be rough on the belt and the battery (s) and use more energy than it saves. How this scheme evolves will tell the story to its entirety.
This is my understanding of how it works. I will read up more on it soon.
But first....I'd like to get a call from my dealer that my car is ready!!

[Gortok]

They say it starts when you take your foot off the brake and is ready to go as soon as you hit the gas...Sounds good as long as it works.
I've started shutting mine off if I know I'll be sitting still for more than 10 seconds. When the lights at the intersection turn to yellow for the other lane, I crank it back up.
I coast downhill in neutral and keep up enough speed (to avoid downshifting out of top gear) going up the next hill.

[Willy]

Originally Posted by jonnysan

When the car comes to a stop such as at a traffic light or stop sign (there must be a short delay on the speedo sensor that tells the ECU it's time to turn off the engine) the engine turns off to conserve fuel and the vehicle's energy needs are supplied by the battery(s). As soon as you start to move again, the speed sensor (or brake light sensor) tells the starter-generator on the serpentine belt plane to restart the engine and it does so. I would think that those starts and stops would be rough on the belt and the battery (s) and use more energy than it saves. How this scheme evolves will tell the story to its entirety.
This is my understanding of how it works. I will read up more on it soon.
But first....I'd like to get a call from my dealer that my car is ready!!

Thanks for the reply...

Is this something that will be an option on the cars, or is it going to be standard equipment. (Or does anyone really know at this point?)

[spdickey]

Originally Posted by Willy

Is this something that will be an option on the cars, or is it going to be standard equipment.

Its an option on Euro smarts, not yet available in the USA.

[Carnut]

The "Green" editions being sold by Saturn already use this technology. It just requires the proper software and a larger Alternator/starter. Really simple, but is at its most efficient in stop and go city driving, or in some cases stop and go freeway driving.

[mdfortwoguy]

The Greenline editions by Saturn do have battery assist, as well.

Does the mhd have battery assist, or is it purely start/stop?

[Carnut]

Originally Posted by mdfortwoguy

The Greenline editions by Saturn do have battery assist, as well.

Does the mhd have battery assist, or is it purely start/stop?

The MT blogger says it only runs on battery at red lights, which probably keeps accessories going. I believe that when you take your foot off of the brake pedal the engine restarts?

[Old smart]

There is another stop-start technology out there that will pre-fire a cylinder to re-start the engine. That would have to presume that there was a known cylinder available somewhere early in the power stroke with the valves closed. I don't know how they do that. A four cylinder engine will always have one cylinder on a power stroke, but it may be nearly at BDC; better chance of a high piston with a 6 or 8. With a 3-cylinder 4-stroke like the smart, it probably can't be done.

[Gortok]

hmmm
Fire all at once?
Computer looks at crank rpm and for TDC/cam position sensor. pick up fuel and spark once it has a signal...??
I just don't know what would happen if the engine didn't spin at all...trigger starter?

That could be a problem...

[Carnut]

http://blogs.motortrend.com/6225330/...rid/index.html