Start Stop System

[Ty]

Back to the Start-Stop system... Bosch has this to say:

Cars don't need to have their engines running when they're stopped at red lights. That's why a number of automakers have developed start-stop systems, which stop a car's engine when the vehicle comes to a halt, and start it again as soon as the gas pedal is pressed. Bosch, however, is taking things farther. Its new start-stop system shuts the engine off not only at stops, but also whenever the car is coasting.
Putting it simply, the "start-stop system with coasting mode" turns off the engine whenever the vehicle can maintain its present speed by rolling. In other words, if the driver's foot isn't on the gas or brake pedals, the engine is off. A simple touch of either pedal causes the engine to instantly start back up.
According to Bosch, tests carried out by the company indicate that most vehicles could coast for about one third of every trip. If the engine was shut off for those periods, it would result in fuel savings of about 10 percent. Additionally, Bosch claims that if every new car sold in Germany were equipped with the system, "the theoretical annual reduction in CO2 would amount to over 30,000 metric tons" (33,069 tons).
What's more, with the engine off, the decreased mechanical resistance should allow cars to coast for longer distances than would otherwise be possible.
The system can reportedly be added to almost any type of existing combustion engine (including hybrids), and requires the installation of relatively few additional parts. It can even be added to cars with manual transmissions, if Bosch's eClutch is also used – this disengages the clutch whenever the vehicle is in coasting mode.
There's no word on availability or pricing of the system, although it is described as "affordable."

I'd like to know their definition of "affordable"... I do a lot of starts and stops on my way to work every day...

 

[Ty]

Automobile mag says this:

Mazda invented the most ingenious automatic stop/start method we've seen so far, called Smart Idle Stop System (SISS). In full accord with the well-known acronym KISS (Keep it Simple, Stupid), SISS does not use the electric starter to crank the engine back to life after shutdown.
SISS's trick is stopping the engine with all of the pistons near the midpoint of their strokes. This is achieved by manipulating the load on the crankshaft via the alternator during shutdown. Holding the throttle wide open allows one cylinder to fill with air.
To restart the engine, fuel is sprayed into the cylinder on its compression stroke and the corresponding spark plug is fired. Combustion drives the piston down, temporarily spinning the crankshaft backward. This reverse rotation compresses the fuel and air in an adjacent cylinder. Firing the spark plug in that cylinder initiates a second combustion event that halts the reverse rotation and restores normal engine operation.


Read more: http://www.automobilemag.com/features/news/0812_smart_idle_stop_system_siss/#ixzz2yVV3Zigq

 

[MJZ]

Doing some research on this, Mazda's system uses the engine itself to assist in the restart process, this eliminates the need for a more powerful battery, more powerful starter unit or any regenerative breaking features. Personally, I think that this would be *THE* best option for the Elio as it only requires potentially an additional sensor bank and some tweaked ECU programming. So Start/Stop without larger components. Mazda reported a 10% fuel savings.

http://www.mazda.com/publicity/release/2008/200809/080909a.html

 

[MJZ]

And I see this has been discussed... *note to self, don't just post from the front page*

 

[Ty]

And I see this has been discussed... *note to self, don't just post from the front page*

LOL... No worries. We've all done that.

 

[Lil4X]

Some hypermiling techniques actually do pay off - staying off the conventional cruise control while driving on overpass-rich freeways is a big one. My first Lexus had an instantaneous and a cumulative mpg display, that provided some fascinating information. During several months of experimentation on my Sunday 20-mile drive to church and 20-mile return (no traffic, almost all on freeways), I discovered my cruise control (operated by the ECU to slavishly maintain speed at all costs) was costing me a fair amount of gas.

Normally, my RX was getting about 24mpg using the cruise control over the freeway portion of the drive, but when I shut off the cruise and simply maintained a steady throttle position, my instantaneous consumption would show an uptick in economy that was confirmed on my cumulative reading on arrival at my destination. The cumulative register would reset whenever the engine was turned off, so it was easy to see the results of each trip individually.

By maintaining a steady throttle position, I'd run the speed limit on flat sections (60 mph), but as we began going up an overpass, the speed would fall off to 55 or 56 mph at the top, then increase to about 63 or 64 on the backside of the hump. Within a couple hundred yards my speed would return to 60, while the instantaneous readout would barely move. At the end of the trip I'd reached 27-28mpg - with a trip time essentially identical to that on the cruise control.

What was happening? Well, watching the instruments, it seems that the ECU would not tolerate any variation in speed, so when I encountered an uphill section, the computer would begin to squeeze on throttle to maintain my preset speed, then more and more as the incline steepened. On the backside of the hump, it would feather it off, but not lift off completely (which would have been kind of jerky). I was consuming a great deal of fuel (about 18mpg on the instantaneous register) going uphill, and about 28 on the downhill while the cruise control maintained speed.

I believe that if Lexus, in it's multiple custom settings had allowed say a 6-7 mph variance in speed over and under the preset, or even allowed that range for as much as 10 seconds before making a correction - and then one much more gentle than the programmed setting that seemed to want to return you to the setpoint within fifty yards, the effect on overall fuel economy could have been pretty dramatic.

No, hypermiling like that shouldn't be the default position of any cruise control because people tend to use them in traffic - no matter how often they are warned. But among all of the other gadgetry cars employ today, there might be a "hypermile" setting that would allow this by offering an alternative to the conventional cruise control logic.

How much difference this would make on the lightweight Elio, I can't say - that RX had AWD and a 3.0L V6 hauling about 4200 lbs. While a middleweight compared to my Suburbans that approached three tons, it wasn't exactly an economy car by any means. On longer trips across the dead flat prairie of Northwest Texas, it would return as much as 28mpg without any hypermiling at all.

 

[Edward]

Some hypermiling techniques actually do pay off - staying off the conventional cruise control while driving on overpass-rich freeways is a big one. My first Lexus had an instantaneous and a cumulative mpg display, that provided some fascinating information. During several months of experimentation on my Sunday 20-mile drive to church and 20-mile return (no traffic, almost all on freeways), I discovered my cruise control (operated by the ECU to slavishly maintain speed at all costs) was costing me a fair amount of gas.

Normally, my RX was getting about 24mpg using the cruise control over the freeway portion of the drive, but when I shut off the cruise and simply maintained a steady throttle position, my instantaneous consumption would show an uptick in economy that was confirmed on my cumulative reading on arrival at my destination. The cumulative register would reset whenever the engine was turned off, so it was easy to see the results of each trip individually.

By maintaining a steady throttle position, I'd run the speed limit on flat sections (60 mph), but as we began going up an overpass, the speed would fall off to 55 or 56 mph at the top, then increase to about 63 or 64 on the backside of the hump. Within a couple hundred yards my speed would return to 60, while the instantaneous readout would barely move. At the end of the trip I'd reached 27-28mpg - with a trip time essentially identical to that on the cruise control.

What was happening? Well, watching the instruments, it seems that the ECU would not tolerate any variation in speed, so when I encountered an uphill section, the computer would begin to squeeze on throttle to maintain my preset speed, then more and more as the incline steepened. On the backside of the hump, it would feather it off, but not lift off completely (which would have been kind of jerky). I was consuming a great deal of fuel (about 18mpg on the instantaneous register) going uphill, and about 28 on the downhill while the cruise control maintained speed.

I believe that if Lexus, in it's multiple custom settings had allowed say a 6-7 mph variance in speed over and under the preset, or even allowed that range for as much as 10 seconds before making a correction - and then one much more gentle than the programmed setting that seemed to want to return you to the setpoint within fifty yards, the effect on overall fuel economy could have been pretty dramatic.

No, hypermiling like that shouldn't be the default position of any cruise control because people tend to use them in traffic - no matter how often they are warned. But among all of the other gadgetry cars employ today, there might be a "hypermile" setting that would allow this by offering an alternative to the conventional cruise control logic.

How much difference this would make on the lightweight Elio, I can't say - that RX had AWD and a 3.0L V6 hauling about 4200 lbs. While a middleweight compared to my Suburbans that approached three tons, it wasn't exactly an economy car by any means. On longer trips across the dead flat prairie of Northwest Texas, it would return as much as 28mpg without any hypermiling at all.

My commute is pretty hilly (this is Colorado, after all), so that's good information to remember if I ever start driving a vehicle with working cruise control again.

 

[Joshua Caldwell]

My dad squeezed 56mpg out of his '86 Toyota Celica GT.... he was in 5th gear by the time we reached 30mph and he made sure to never exceed 1500rpm.

 

[BlioKart]

Some hypermiling techniques actually do pay off - staying off the conventional cruise control while driving on overpass-rich freeways is a big one. My first Lexus had an instantaneous and a cumulative mpg display, that provided some fascinating information. During several months of experimentation on my Sunday 20-mile drive to church and 20-mile return (no traffic, almost all on freeways), I discovered my cruise control (operated by the ECU to slavishly maintain speed at all costs) was costing me a fair amount of gas.

Normally, my RX was getting about 24mpg using the cruise control over the freeway portion of the drive, but when I shut off the cruise and simply maintained a steady throttle position, my instantaneous consumption would show an uptick in economy that was confirmed on my cumulative reading on arrival at my destination. The cumulative register would reset whenever the engine was turned off, so it was easy to see the results of each trip individually.

By maintaining a steady throttle position, I'd run the speed limit on flat sections (60 mph), but as we began going up an overpass, the speed would fall off to 55 or 56 mph at the top, then increase to about 63 or 64 on the backside of the hump. Within a couple hundred yards my speed would return to 60, while the instantaneous readout would barely move. At the end of the trip I'd reached 27-28mpg - with a trip time essentially identical to that on the cruise control.

What was happening? Well, watching the instruments, it seems that the ECU would not tolerate any variation in speed, so when I encountered an uphill section, the computer would begin to squeeze on throttle to maintain my preset speed, then more and more as the incline steepened. On the backside of the hump, it would feather it off, but not lift off completely (which would have been kind of jerky). I was consuming a great deal of fuel (about 18mpg on the instantaneous register) going uphill, and about 28 on the downhill while the cruise control maintained speed.

I believe that if Lexus, in it's multiple custom settings had allowed say a 6-7 mph variance in speed over and under the preset, or even allowed that range for as much as 10 seconds before making a correction - and then one much more gentle than the programmed setting that seemed to want to return you to the setpoint within fifty yards, the effect on overall fuel economy could have been pretty dramatic.

No, hypermiling like that shouldn't be the default position of any cruise control because people tend to use them in traffic - no matter how often they are warned. But among all of the other gadgetry cars employ today, there might be a "hypermile" setting that would allow this by offering an alternative to the conventional cruise control logic.

How much difference this would make on the lightweight Elio, I can't say - that RX had AWD and a 3.0L V6 hauling about 4200 lbs. While a middleweight compared to my Suburbans that approached three tons, it wasn't exactly an economy car by any means. On longer trips across the dead flat prairie of Northwest Texas, it would return as much as 28mpg without any hypermiling at all.

I hyper mile my car while it doesn't have cc I have driven many cars with cc. I can always beat the cc on gas mileage. I only want cc for the flat areas I can do the rest. Its a nice option to have but not necessary.

 

[Edward]

My dad squeezed 56mpg out of his '86 Toyota Celica GT.... he was in 5th gear by the time we reached 30mph and he made sure to never exceed 1500rpm.

My '87 Corolla didn't have a tach, but I shifted like your dad and I routinely got 33-35mpg in that thing.