Turning engine off and on is bad?

[thescreensavers]

So I know some new cars have the "Start-stop" tech

But someone in one of my classes said that the engine turning on and off at every stop light is bad for it.


Now If you stop the engine for a brief period oil has still not drained back, also if its FSI it uses almost no fuel to turn the engine back on.

From what I believe the only thing this is bad for is the starter which could just be beefed up and it will all be good?

Am I missing something?

 

[LTC8K6]

The battery and alternator and starter will suffer.

Cars with such stop/start systems have components or systems designed for this behavior.

 

[Gibson486]

Isn't that what a hybrid does?

 

[DivideBYZero]

I have a car that has stop/start tech. It has a beefed up Starter and during cold weather it actually suspends stop/start activity.

 

[Demo24]

Well unlike a regular car the electronic systems will stay active. Thus the oil pump and fuel pump will remain on so there is no loss there. The engine won't shut off in certain situations such as high electrical load, air con needed, or if the engine is not within the correct operating temperature. It also seems to be more common on manual cars. I've driven one with this tech before and at first it was disturbing as the car simply shut down but everything else stayed the same. Push in the clutch, boom up it goes again and best of all no electrical cut so it's quite seamless. It won't stay off forever if your sitting in traffic not going anywhere it will cut in and out as needed. The starter has been really beefed up so the engines crank very quickly, by the time I was managing to put the transmission in first the engine was already good to go.

I want to say the engines also try to stop in a certain firing order so as to ease and quicken restart, but I can't be certain this is correct information.

 

[Doppel]

So I know some new cars have the "Start-stop" tech

But someone in one of my classes said that the engine turning on and off at every stop light is bad for it.


Now If you stop the engine for a brief period oil has still not drained back, also if its FSI it uses almost no fuel to turn the engine back on.

From what I believe the only thing this is bad for is the starter which could just be beefed up and it will all be good?

Am I missing something?

It depends on the motor. There are considerations and changes necessary but turning off an old engine and on regularly is not the same as a newer motor with this engineered into it. The Prius starts/stops way, way more than the average car and is just fine. There are tweaks other manufacturers make as well when integrating these approaches, such as Ford with its idle-stop.

I want to say the engines also try to stop in a certain firing order so as to ease and quicken restart, but I can't be certain this is correct information.

Mazda has explored this. I don't know if they have it or will have it in production, though.

 

[Howard]

It depends on the motor. There are considerations and changes necessary but turning off an old engine and on regularly is not the same as a newer motor with this engineered into it. The Prius starts/stops way, way more than the average car and is just fine. There are tweaks other manufacturers make as well when integrating these approaches, such as Ford with its idle-stop.Mazda has explored this. I don't know if they have it or will have it in production, though.

They do.

 

[jhu]

I do it at long stop lights if I'm unable to adequately catch the green light.

 

[thescreensavers]

Well unlike a regular car the electronic systems will stay active. Thus the oil pump and fuel pump will remain on so there is no loss there. The engine won't shut off in certain situations such as high electrical load, air con needed, or if the engine is not within the correct operating temperature. It also seems to be more common on manual cars. I've driven one with this tech before and at first it was disturbing as the car simply shut down but everything else stayed the same. Push in the clutch, boom up it goes again and best of all no electrical cut so it's quite seamless. It won't stay off forever if your sitting in traffic not going anywhere it will cut in and out as needed. The starter has been really beefed up so the engines crank very quickly, by the time I was managing to put the transmission in first the engine was already good to go.

I want to say the engines also try to stop in a certain firing order so as to ease and quicken restart, but I can't be certain this is correct information.

isnt the oil pump belt/chain driven?

Anyhow yea so if I car is engineered to do so, battery/alternator and starter made for the application its not bad.

 

[Zenmervolt]

Well unlike a regular car the electronic systems will stay active. Thus the oil pump and fuel pump will remain on so there is no loss there.

Oil pumps are still gear-driven except in very high-end exotics or race engine builds. Even with the electrical system active, they aren't going to keep running if the engine isn't spinning. Also, EFI fuel systems have check valves to maintain pressure at the fuel rail even while the fuel pump is off, so fuel pressure won't bleed to zero for quite a while after shutting the engine off.

ZV

 

[bruceb]

I would prefer it stay running at traffic lights. What happens if someone comes speeding up behind you and you need to get out of the way, assuming you have enough room to do so and you can't move quick enough since motor is not yet running ? ? Now you have an accident that you might have been able to avoid. No thanks.

 

[Doppel]

I would prefer it stay running at traffic lights. What happens if someone comes speeding up behind you and you need to get out of the way, assuming you have enough room to do so and you can't move quick enough since motor is not yet running ? ? Now you have an accident that you might have been able to avoid. No thanks.

Ford I think has their restart down to .3 seconds. I am not sure how others perform. Although what you say is feasible I've never in my life experienced nor heard of anybody ever tell me experiencing such a situation in which a quick get away like this saved them from anything. It's so fringe as to be irrelevant in the scheme of things.

 

[DivideBYZero]

I would prefer it stay running at traffic lights. What happens if someone comes speeding up behind you and you need to get out of the way, assuming you have enough room to do so and you can't move quick enough since motor is not yet running ? ? Now you have an accident that you might have been able to avoid. No thanks.

By the time you have the clutch depressed the engine is already running. No difference.

 

[Demo24]

Oil pumps are still gear-driven except in very high-end exotics or race engine builds. Even with the electrical system active, they aren't going to keep running if the engine isn't spinning. Also, EFI fuel systems have check valves to maintain pressure at the fuel rail even while the fuel pump is off, so fuel pressure won't bleed to zero for quite a while after shutting the engine off.

ZV

My mistake, didn't know that.

 

[exdeath]

Ford I think has their restart down to .3 seconds. I am not sure how others perform. Although what you say is feasible I've never in my life experienced nor heard of anybody ever tell me experiencing such a situation in which a quick get away like this saved them from anything. It's so fringe as to be irrelevant in the scheme of things.

I've avoided two rear endings by pulling into the left or right turn lane. .3 seconds hardly matters. I had time to see the car coming too fast, see the expression on the persons face in my mirror, put it in gear and turn the wheel, and hear the skidding for a good second or two and judge their stopping distance while I made a final decision to move. Time slows down and you have all day to respond in those circumstances. Helps that I'm a very alert and observant person and that I pay more attention to my rear view than I do to what's in front of me, because I can trust myself, I can't trust other drivers.