Go Back   Team-BHP > Under the Hood > Technical Stuff


Closed Thread
 
Thread Tools Search this Thread
Old 1st May 2007, 22:49   #31
BHPian
 
austere_sly's Avatar
 
Join Date: Mar 2007
Location: New Delhi
Posts: 287
Thanked: 9 Times
Default

Just a question here. I drive Swift Diesel. It has a turbo lag and the turbo kicks in at around 2000 rpm. So does that means that before 2000 rpm turbo isn't working at all or is it not rotating hard enough.
If my the last part of my drive say the last 2 kms have been slow in traffic and the turbo didn't get a chance to come into play, then in such cases can i turn off the enfine sooner than what i normally do i.e. gap of 30 secs.

Thanks
austere_sly is offline  
Old 2nd May 2007, 11:46   #32
GTO
Team-BHP Support
 
GTO's Avatar
 
Join Date: Feb 2004
Location: Bombay
Posts: 47,715
Thanked: 88,946 Times
Default

Quote:
So does that means that before 2000 rpm turbo isn't working at all or is it not rotating hard enough.
Austure, of course it is working. But it just has not "spooled" up enough for thrust.
GTO is offline  
Old 2nd May 2007, 23:04   #33
BHPian
 
Su-47's Avatar
 
Join Date: Aug 2006
Location: Bangalore
Posts: 623
Thanked: 91 Times
Default

Quote:
Originally Posted by Steeroid View Post
I do, and it doesnt say anything. Its another matter that I always idle for a while on both start and stop, though.
I'm glad that you idle on start and stop.

The Safari-Dicor Owner's manual does recommend a 30-sec idling period on start/stop. Not sure if it is a new addition, but my car's manual has it.

Last edited by Su-47 : 2nd May 2007 at 23:05.
Su-47 is offline  
Old 2nd May 2007, 23:27   #34
Senior - BHPian
 
hvkumar's Avatar
 
Join Date: Nov 2006
Location: Mumbai
Posts: 7,369
Thanked: 3,354 Times
Default

Mahindra Scorpio comes with warning sticker and manual instructions that engine should be run in idle mode 1 minute before and after you stop or start it.
hvkumar is offline  
Old 7th May 2007, 03:35   #35
BHPian
 
Join Date: Feb 2005
Location: mumbai
Posts: 66
Thanked: 2 Times
Default add

Quote:
Originally Posted by shazikon View Post
This is not the real reason why you to idle for 30 secs before switching off. The turbo gets really hot because of high RPM at which it runs.
.
.
.
.
The engine should be running for the oil pump to work. To over come this problem, turbo timers are available which keep the engine running for specified amount of time even if you lock and leave.. the turbo timer runs the engine and switches the engine OFF after the specified time. thus keeping the turbo bearings lubricated and cool.
more so in a petrol as comp to a diesel. but principle is the same. easy on starting till warm and coast before shutdown especially if you ve been driving hard
air870 is offline  
Old 6th May 2008, 15:07   #36
Senior - BHPian
 
shankar.balan's Avatar
 
Join Date: Apr 2008
Location: BLR
Posts: 8,027
Thanked: 5,325 Times
Default

where are such turbo timers available?
can you recommend where I can buy one in Bangalore?
thanks

Quote:
Originally Posted by shazikon View Post
This is not the real reason why you to idle for 30 secs before switching off. The turbo gets really hot because of high RPM at which it runs. Because of the high RPMS ( ~200,000 RPM) the bearing which holds the turbine gets superhot and even the lubrication gets very hot. The only wat the ball bearings ( ceramic or steel) can cool down is from the oil it feeds directly from the oil sump of the crank. while the engine is running the oil is circulating through the inlet to the ball bearings fed by the oil pump. when you suddenly stop the engine after a hard run, the bearings are still super hot and not yet cooled down and the oil supply is cut off - no cooling. Prolonged abuse of the bearings will burn the bearings and cause turbo failure. This is the reason why it is advised to keep the engine running so that the turbo bearings are fed with oil from the oil pump. The engine should be running for the oil pump to work. To over come this problem, turbo timers are available which keep the engine running for specified amount of time even if you lock and leave.. the turbo timer runs the engine and switches the engine OFF after the specified time. thus keeping the turbo bearings lubricated and cool.
shankar.balan is offline  
Old 6th May 2008, 16:49   #37
Senior - BHPian
 
V-16's Avatar
 
Join Date: May 2005
Location: mumbai
Posts: 4,575
Thanked: 843 Times
Default

Quote:
Originally Posted by hvkumar View Post
Mahindra Scorpio comes with warning sticker and manual instructions that engine should be run in idle mode 1 minute before and after you stop or start it.
This warning is also in the Diesel Innova and I believe, a host of Tata cars that are turbo charged.
V-16 is offline  
Old 7th May 2008, 00:40   #38
Senior - BHPian
 
Join Date: Sep 2006
Location: zxc
Posts: 3,394
Thanked: 658 Times
Default

Quote:
Originally Posted by shankar.balan View Post
where are such turbo timers available?
can you recommend where I can buy one in Bangalore?
thanks
Turbo timers
Explanation on turbo timers
Attached Images
 
SirAlec is offline  
Old 7th May 2008, 08:15   #39
BHPian
 
Ford Rocam's Avatar
 
Join Date: Feb 2005
Location: Mumbai-India
Posts: 880
Thanked: 16 Times
Default

Quote:
Originally Posted by V-16 View Post
This warning is also in the Diesel Innova and I believe, a host of Tata cars that are turbo charged.
Do factory fitted petrol turbo vehicles like Skoda VRS has any such warning?
Ford Rocam is offline  
Old 7th May 2008, 13:00   #40
HPP
BHPian
 
Join Date: Mar 2008
Location: Minneapolis, MN/Hyderabad
Posts: 232
Thanked: 2 Times
Default

Pretty much all turbos will benefit from being idled before being shut down.
HPP is offline  
Old 19th August 2008, 13:55   #41
Senior - BHPian
 
shankar.balan's Avatar
 
Join Date: Apr 2008
Location: BLR
Posts: 8,027
Thanked: 5,325 Times
Default

when you start a turbo vehicle like your DI Bolero or the Scorpio you are supposed to idle for 30 sec and then move. While stopping, you are supposed to go a bit easy for a bit, just before coming to a dead halt, then idle for another 30 sec and then switch off.
I ve also been in doubt about this and have checked with several TBHP members who own Turbo vehicles and this is what I ve learned from them.

Quote:
Originally Posted by Rough Square View Post
But the trouble is - there is a sticker on my dash board which says idle for 1 minute before switching on and before switching off. Thats about 120 seconds.

So what do the rest of you do?
shankar.balan is offline  
Old 19th August 2008, 14:21   #42
Senior - BHPian
 
greenhorn's Avatar
 
Join Date: Apr 2007
Location: TN-14
Posts: 6,833
Thanked: 1,309 Times
Default

those of us who have a turbo know at what rpm it kicks in.
Just drive it far below that threshold , and as close to idle rpm as possible for a minute before shutting it down
greenhorn is offline  
Old 19th August 2008, 14:44   #43
Team-BHP Support
 
tsk1979's Avatar
 
Join Date: Feb 2005
Location: New Delhi
Posts: 22,953
Thanked: 15,638 Times
Default

Turbo starts spinning once you start the engine. As engine rpm rises, your turbo spins faster.

So when you do a cold start there is still a period where the turbo spins dry, but due to low speed there is no damage.
However if you start engine and then rev the engine, you are looking at turbo damage.
Sadly when you give your cars for service, none of the mechanics at any workshop(I have seen Tata Mahindra and Hyundai) idle the vehicle.
For them its full throttle from word go.
tsk1979 is offline  
Old 19th August 2008, 15:10   #44
BHPian
 
viper_711's Avatar
 
Join Date: Jan 2008
Location: Bangalore
Posts: 346
Thanked: 55 Times
Default

My understanding is like this:
On a cold engine I agree with what tsk is saying and hence religiously follow the 1 min idling before rolling off. I also follow the 30 second idling before engine shut-off when I know that the car is not going to be in use for at least one hour.

On signals, what green horn has said is what makes sense (about staying at low RPM's) and I follow the same procedure. On a warmed up engine - the engine oil is hot and at the viscosity it's supposed to be at (Hence coming into effect quicker). I see no harm in killing the engine at signals. I just ensure i start about 10 seconds before it goes green.

Last edited by viper_711 : 19th August 2008 at 15:14.
viper_711 is offline  
Old 19th August 2008, 15:17   #45
Team-BHP Support
 
tsk1979's Avatar
 
Join Date: Feb 2005
Location: New Delhi
Posts: 22,953
Thanked: 15,638 Times
Default

viper its nothing to do with viscosity.
when engine is shut off, the oil pump stops and no oil is sent to turbo.
So if you were at revs where turbo was spinning fast, when you switch off your turbo will run dry for more time.

If you idle you allow turbo to come to a slower speed. So when you shut off engine, oil supply stops and slowly turbo comes back to 0.
At full boost I am told turbo's can touch 20,000rpm
tsk1979 is offline   (1) Thanks
Closed Thread


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Turbos on Indian off-road vehicles DirtyDan 4x4 Technical 101 27th October 2015 21:44
Inconsistent idling and engine shut off problem DCEite Technical Stuff 17 18th May 2012 22:37
Warming Up / Idling Engine before starting off... 911turbo Technical Stuff 29 23rd May 2009 13:02
Fiat India : How much longer before they shut down? GTO The Indian Car Scene 378 12th February 2009 13:35
Idling the Turbo engines before switching off.. Could this be a solution? DRC Technical Stuff 14 5th April 2006 21:19


All times are GMT +5.5. The time now is 09:50.

Copyright 2000 - 2017, Team-BHP.com
Proudly powered by E2E Networks