[sandeepmohan]

A Animagraff on how Turbochargers and Superchargers work.

http://animagraffs.com/supercharger-vs-turbo/

[ajayclicks]

Guys, not sure if this has been covered. A quick search threw a blank. While the general consensus is that one need not idle the car for too long (from a cold start), and my user manual too does not say that I have to idle the car before driving, how do we then use a vacuum cleaner or a portable tire inflator that run on the cigarette lighter port? The inflator could be used for atleast 5 mins per tire, and the vacuum cleaner for almost 20 mins or so. Any best practices here?

[sgiitk]

One think which is bothering me. Some of the 'soft hybrids' whatever they mean, switch off the engine after a few seconds. They restart it when you press the throttle. What happens to the gentle cooling off period?

[a4anurag]

Originally Posted by sgiitk

What happens to the gentle cooling off period?

Yes sir, I have got that don't too as Scorpio, XUV, Ciaz, Ertiga get this 'intelligent' Start-Stop system.

So could there be a secondary way to cool the turbo?

[Jeroen]

Originally Posted by sgiitk

One think which is bothering me. Some of the 'soft hybrids' whatever they mean, switch off the engine after a few seconds. They restart it when you press the throttle. What happens to the gentle cooling off period?

Unless you have been giving it some real heavy stick there isn't that much cooling off that needs doing. As discussed before plenty of Turbo's out there that don't need it. If it's not mentioned in the owners manual it's not needed.
If it is I would imagine it's very simple to have a cool down period programmed based on available parameters in the ECU so the engine doesn't stop immediately but life's for whatever time period is appropriate

Jeroen

[ajayclicks]

Originally Posted by sgiitk

One think which is bothering me. Some of the 'soft hybrids' whatever they mean, switch off the engine after a few seconds. They restart it when you press the throttle. What happens to the gentle cooling off period?

Originally Posted by a4anurag

Yes sir, I have got that don't too as Scorpio, XUV, Ciaz, Ertiga get this 'intelligent' Start-Stop system.

So could there be a secondary way to cool the turbo?

Originally Posted by Jeroen

If it is I would imagine it's very simple to have a cool down period programmed based on available parameters in the ECU so the engine doesn't stop immediately but life's for whatever time period is appropriate
Jeroen

This is what my XUV500 manual says:

On idling before driving:

After idling for a few seconds, release the parking brake, depress the clutch, shift the gear shift lever to 1st g......

Avoid full throttle operation when the engine is cold and prolonged idling at low ambient temperatures. Long periods of idling may be harmful to your engine......

On idling after driving:

Your vehicle is powered by a turbo diesel engine. Before turning the engine OFF, always allow the engine to return to normal idle speed and run for few seconds. This assures proper cooling and lubrication of the turbocharger. This is particularly necessary after any hard driving.

On start-stop function:

For auto stop to happen the following conditions are to be met: (reproducing only two conditions from the list provided):

• Engine is warm (Engine coolant temperature is between 25 °C and 100 °C). This is an extra precaution to ensure safe working of the engine

• Fuel temperature is less than 60 °C

I guess this last bullet point will take care of the turbo cooling issue.

[asingh1977]

Originally Posted by ajayclicks

On idling after driving:

Your vehicle is powered by a turbo diesel engine. Before turning the engine OFF, always allow the engine to return to normal idle speed and run for few seconds. This assures proper cooling and lubrication of the turbocharger. This is particularly necessary after any hard driving.

I could be totally stupid, but asking a question about the XUV. Suppose you come in from a normal city drive, and park at your basement. How long does it take the RPM needle to fall to normal. Does it actually do this...? How does one know, that a vehicle is now idling at normal speeds. With no gear engaged.

Also @ All:
Is it all right to put on the car AC as soon as it is cold-started..? I have noticed the RPM needle move a bit up, once the AC is put on.

[ajayclicks]

Originally Posted by asingh1977

I could be totally stupid, but asking a question about the XUV. Suppose you come in from a normal city drive, and park at your basement. How long does it take the RPM needle to fall to normal. Does it actually do this...? How does one know, that a vehicle is now idling at normal speeds. With no gear engaged.

I never really bother. I have basement parking, so by the time I navigate the mad traffic outside my apartment, enter, and make my way through basement, it is 5- 10 mins in the second gear (or less). Plus I do some small stuff like switching off the a/c, picking up my phone etc. before I switch off the engine.

[Jeroen]

Originally Posted by asingh1977

Is it all right to put on the car AC as soon as it is cold-started..? I have noticed the RPM needle move a bit up, once the AC is put on.

No problem. A typical AC takes maybe 3-4 horsepower, so as you switch it on the engine gets loaded up and adjust itself, on some engines that means a slightly higher idle.

On most modern cars you can just leave the AC on when you switch the engine off and start again the next morning. The ECU will ensure no AC is running untill the engine is properly running at normal idle.
Jeroen

[amitpunjani]

Originally Posted by Jeroen

No problem. A typical AC takes maybe 3-4 horsepower, so as you switch it on the engine gets loaded up and adjust itself, on some engines that means a slightly higher idle.

On most modern cars you can just leave the AC on when you switch the engine off and start again the next morning. The ECU will ensure no AC is running untill the engine is properly running at normal idle.
Jeroen

Jeroen,

I doubt if this statement is also valid for Maruti Swift/Ertiga. As in these cars, the moment fire the engine in the morning, the driver can switch on the Aircon and it will come to life.

[Jeroen]

Originally Posted by amitpunjani

Jeroen,



I doubt if this statement is also valid for Maruti Swift/Ertiga. As in these cars, the moment fire the engine in the morning, the driver can switch on the Aircon and it will come to life.

Could be, you would have to check. But if the engine starts normal the AC can engage almost immediately.

And in all honesty, any engine with a good battery and starter is perfectly capable of starting even with the AC switched on. It just draws a slightly higher Current.

It more a precaution to switch the AC off before starting. It's like pushing the clutch in on starting. As long as you are In neutral it doesn't matter. Many people, like me would still do so. Why, because it makes the engine start slightly easier on the battery and starter.

These things only become material when it is very cold and therefor your battery is less efficient. Or if you have a very wonky starter. Any load you can shed, do so, so no AC, press the clutch.

Jeroen

[arunphilip]

Originally Posted by Jeroen

Many people, like me would still do so.

I'm also old-fashioned like that - push the clutch, put it in neutral when starting up, and turn off all accessories when shutting down.

Originally Posted by Jeroen

On most modern cars you can just leave the AC on when you switch the engine off and start again the next morning. The ECU will ensure no AC is running untill the engine is properly running at normal idle.

I get your point about the AC loading the engine. But, how about the blower motor? That starts running even before the engine is cranked - would it take away a significant amount of power from the starter/glow plugs to be a problem? I couldn't find a quick reference to the load rating of the motor, but my car's manual states the blower fuse is 40A (which is large, but is still a far cry from the 450A fuse used for the starter).

[dark.knight]

Originally Posted by arunphilip

I get your point about the AC loading the engine. But, how about the blower motor? That starts running even before the engine is cranked - would it take away a significant amount of power from the starter/glow plugs to be a problem?

Technically the car can take it, if I remember correctly, there were two occasions where I'd to re-start the car in peak traffic immediately hence had no time to switch off the stereo or aircon, the engine buzzed to life as normal. Of course I assume that most cars have the routine of killing the accessories just a fraction of a second before start and then it all comes back to life again, that's the case in my car and I've always found it useful as all the power goes to the starter upon ignition and then are re-routed to the accessories as required.

I think this has a dual purpose, one to protect the accessories from surges and 2ndly to provide full power to the starter thus guaranteeing a first time start unless the battery is very weak. Headlamps are the one exception to this rule I believe as they're wired straight to the battery and not through ignition.

Guess what we all do is more like taking the most cautious route, just like we switch the t.v off from the remote first rather than go straight for the switch, or like not opening the fridge just before plugging in, the sequence simply doesn't feel right. There are enough and more overrides being built into the ECM and BCM of cars these days but yet we want to take our own precautions as well, one day I was wiping my car while listening to music (very low level) and then an elderly neighbour who also happens to be a mech engineer came to me and lectured about battery life going down if I do so, I knew all of that perfectly well, but I guess I felt that I personally could be careless to that extent seeing that it may (or may not) reduce life by fraction percentages.

I follow the clutch+ignition+no accessories rule when starting, the clutch part I have no choice anyway since without pressing it the car won't start and I feel that's an awesome safety override.

[Jeroen]

Originally Posted by dark.knight

Headlamps are the one exception to this rule I believe as they're wired straight to the battery and not through ignition.

On just about all cars I’m familiar only parking lights are wired into the battery. Everything else needs the ignition on, to work properly.

Originally Posted by dark.knight

I follow the clutch+ignition+no accessories rule when starting, the clutch part I have no choice anyway since without pressing it the car won't start and I feel that's an awesome safety override.

Here’s my starting routine:

- Turn ignition on
- Listen for the fuel pump(s) to come on, built pressure and stop again
- On modern cars, wait for the system check annunciation on the dash goes off
- Start engine
- Check oil pressure lights goes off, or pressure up if there is a dial
- Switch on stuff like AC, radio, lights heaters etc.

There is really very little rationale behind that, other then I’m an engineer and part time pilot so I like to do things by strict routine.

Also, I love flicking switches and looking at dials!

Jeroen

[asingh1977]

Originally Posted by Jeroen

It more a precaution to switch the AC off before starting. It's like pushing the clutch in on starting. As long as you are In neutral it doesn't matter. Many people, like me would still do so. Why, because it makes the engine start slightly easier on the battery and starter.

Could you elaborate a bit more on starting the car with the clutch pressed in, and being in N. How is this easier on the battery and starter armature. My wife always starts the vehicle in this method, I do not. Is it different for petrol vs. diesel induced..?