How long can we leave the car running?

SubaruSVXCrazy · #1 04-09-2008, 11:10 AM

For conserving gas, did you ever hear about letting your car idle for a short time insead of turning it off? Because it takes more gas to start it up. How long is too much, it take for it to idle using more gas than a startup? Making it not worth to leave the 3.3 running.

If you can understand this. For loss of better wording.

~*~JenSVX~*~ · #2 04-09-2008, 11:18 AM

I left my car running while I was at work once for 5 hours... I don't think that saved gas though..

crazyhorse · #3 04-09-2008, 11:34 AM

My thoughts would be, that if it's less than 30 seconds or so, leaving it running, would be a fuel saver. For 30sec, or more, it's more efficent to turn the car off.

Manarius · #4 04-09-2008, 02:25 PM

Quote:

Originally Posted by SubaruSVXCrazy

For conserving gas, did you ever hear about letting your car idle for a short time insead of turning it off? Because it takes more gas to start it up. How long is too much, it take for it to idle using more gas than a startup? Making it not worth to leave the 3.3 running.

If you can understand this. For loss of better wording.

I don't see why it would take anymore gas to startup than it would to run the car. This isn't 1960. We have fuel injection now. I turn off my car if I'm sitting at a stoplight for longer than 15 seconds.

bwb3 · #5 04-09-2008, 05:21 PM

Why do truckers leave their diesel engines running whe parked? Not related to that question, I'll leave mine running for short periods because I think it's easier on the car than running through the cycle of start up. Does that make sense? 5 hours? That's stretching it. Did someone lock the keys in the car?
Gene

Subix · #6 04-09-2008, 05:23 PM

Quote:

Originally Posted by Manarius

I don't see why it would take anymore gas to startup than it would to run the car. This isn't 1960. We have fuel injection now. I turn off my car if I'm sitting at a stoplight for longer than 15 seconds.

Somehow I vision you going through starters like a pack of chewing gum....

ensteele · #7 04-09-2008, 08:27 PM

I would not turn it off unless it was going to be more than a couple of minutes - like at a long light. Your starter is going to wear out if you stop the car every couple of minutes.

Crazy_pilot · #8 04-09-2008, 08:31 PM

I never shut my car off on the road. You never know, my car's been reliable, but there's always a chance it won't start up again.

Drivers of turbo'd cars are told to let the car idle for a minute or two after a spirited drive so the coolant can pull some heat away from the turbo and prevent severe heat soak/damage/expensive badness. That's what a turbo timer is all about, it will keep the car running for a minute or so after you remove the key.

~*~JenSVX~*~ · #9 04-09-2008, 08:39 PM

Quote:

Originally Posted by bwb3

5 hours? That's stretching it. Did someone lock the keys in the car?
Gene

Nope, door was wide open... SVX idles too low. I didn't even know it was running till the end of my shift when I went to get my keys and they were missing... Then I checked the car and even after walking up to it didn't realize it was running until I opened the door....

YourConfused · #10 04-09-2008, 08:56 PM

Quote:

Originally Posted by JenSVX

Nope, door was wide open... SVX idles too low. I didn't even know it was running till the end of my shift when I went to get my keys and they were missing... Then I checked the car and even after walking up to it didn't realize it was running until I opened the door....

Are you blonde? (sorry just had to say it, I know you aren't)

~*~JenSVX~*~ · #11 04-09-2008, 09:00 PM

Quote:

Originally Posted by YourConfused

Are you blonde? (sorry just had to say it, I know you aren't)

haha no.... Definitely a blond moment though... It was a stressful day of my life... First day back to work after a 3yr relationship break up...

Now at least I can smile about it though, silly moment that nothing mechanically wrong came from...

YourConfused · #12 04-09-2008, 09:03 PM

Quote:

Originally Posted by JenSVX

haha no.... Definitely a blond moment though... It was a stressful day of my life... First day back to work after a 3yr relationship break up...

Now at least I can smile about it though, silly moment that nothing mechanically wrong came from...

cool, glad you didn't take it the wrong way

IceBlade · #13 04-09-2008, 09:17 PM

Quote:

Originally Posted by bwb3

Why do truckers leave their diesel engines running whe parked?
Gene

I know in the winter it's to keep the heat going. Other than that I haven't a clue. I'll ask my father when he gets back from wherever he is. He's a trucker.

Chris · #14 04-09-2008, 11:11 PM

There are several reasons that over the road truckers idle their vehicles while parked and or even sleeping.

Diesels are hard to start when cold. The fuel in diesel engines is fully ignited by nothing more than heat of compression. Therefore cold motor, harder to start.
Diesel motors do not have throttle butterflies. The intake system is wide open minus turbo compressor if the engine is turbo charged. This means the engine has no restriction sucking in air. A gasoline engine has throttle butterflies that act like a valve to meter the amount of air entering the engine (thusly the sucking sound you hear if you open your air box). This type of design actually chokes the engine at idle and actually reduces efficiency. To visualize this imagine two large syringe like turkey basters. Mark one as gasoline the other as diesel. On the tip of the gas one, put a reducer that will only allow about 10 percent of the air in. On the other, leave it wide open. Pull the handles to suck in air. This was the intake stroke on both engines. What engine labored less to idle? The diesel.
The lubrication system on a large diesel engine is many times more complex then a gas motor. In principal, the roles are the same, but in the larger diesel motor, the oil has to travel UP and THROUGH much more distances and from a cold start, it can take time before all the parts become pressurized with oil. Start ups are where most of the wear in all internal combustion engine take place (barring physical damage).
Due to the insane compression ratios used but diesel engines, the starters require much more torque and energy to turn over the engine for starting. This is taxing on the starter and electrical system. Diesel starters typically cost 3x or more than a standard gasoline engine starter.
Lastly, the drivers do like residual heat in their cabs while they nap

Hope this helps

cozykat · #15 04-09-2008, 11:19 PM

Quote:

Originally Posted by JenSVX

Nope, door was wide open... SVX idles too low. I didn't even know it was running till the end of my shift when I went to get my keys and they were missing... Then I checked the car and even after walking up to it didn't realize it was running until I opened the door....

If it was my svx, the doors would have automatically locked behind me... i've had friends learn that the hard way.