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


Reply
 
Thread Tools Search this Thread
Old 7th May 2011, 15:54   #31
Distinguished - BHPian
 
dhanushs's Avatar
 
Join Date: Oct 2009
Location: Bathery/BLR
Posts: 3,446
Thanked: 4,055 Times
Default Re: Turbo Lag 101

Quote:
Originally Posted by vina View Post
Is there some kind of a "reverse turbo lag" too?

For past few days I have noticed something:

When I'm driving my Figo at 1300rpm it generates a lot of power. Now if I drive for some time (30 seconds) at that rpm, and then shift up, the rpm drops below 1000 but the power doesn't drop much for several seconds.

On the other hand if I'm coming from a low rpm (say roughly 700, 800) into 1000 rpm, it takes several seconds before power develops.
Vina, I believe what you are experiencing is just the effect of inertia, of the car, the rotating parts of the engine and also the turbo.

Figo is a car with very minimal turbo lag, but then below 900rpm, it is really sluggish. Vina, one small advise to you. Always try to keep the rev's above the idle rpm. Anything below it, and you will be seriously lugging the engine. It will also affect, driveability, throttle response, and even fuel efficiency adversely.

Last edited by dhanushs : 7th May 2011 at 15:56.
dhanushs is offline   Reply With Quote
Old 7th May 2011, 16:05   #32
Senior - BHPian
 
Join Date: Dec 2010
Location: Ghaziabad/Hyderabad/Mysore
Posts: 1,416
Thanked: 313 Times
Default Re: Turbo Lag 101

Quote:
Originally Posted by dhanushs View Post
Vina, I believe what you are experiencing is just the effect of inertia, of the car, the rotating parts of the engine and also the turbo.

Figo is a car with very minimal turbo lag, but then below 900rpm, it is really sluggish. Vina, one small advise to you. Always try to keep the rev's above the idle rpm. Anything below it, and you will be seriously lugging the engine. It will also affect, driveability, throttle response, and even fuel efficiency adversely.
I'm trying to follow your advice on the idle rpm - but I'm a knew driver (and learned on a petrol), it'll take a few weeks of practice.

Coming to "reverse turbo" I though it was the inertia too at first - but it is not. I'm not talking about whether the car continues to move - I'm talking about noticeable pickup that I can feel on my back when the seat rushes into it.

Also it can not be rotary inertia of the engine - the rpm did fall, and I have seen severe engine braking effects if I just downshift without pressing the accelerator.

My guess is the the turbo is compressing air into some chamber and the chamber maintains high pressure for a few seconds even though rpm has fallen. Turbo's inertia might be helping too, though if that is the case then turbo lag (measured in seconds it takes to spool, rather than rpm) would be worse - more time will be needed to spool a turbo with higher rotational inertia.
vina is offline   Reply With Quote
Old 7th May 2011, 18:12   #33
BANNED
 
Join Date: Feb 2010
Location: New Delhi
Posts: 1,316
Thanked: 233 Times
Default Re: Turbo Lag 101

Quote:
Originally Posted by vina View Post
Is there some kind of a "reverse turbo lag" too?

For past few days I have noticed something:

When I'm driving my Figo at 1300rpm it generates a lot of power. Now if I drive for some time (30 seconds) at that rpm, and then shift up, the rpm drops below 1000 but the power doesn't drop much for several seconds.

On the other hand if I'm coming from a low rpm (say roughly 700, 800) into 1000 rpm, it takes several seconds before power develops.


For the Figo TDCi, anything above 1000 RPM will produce negligible lag, However if you are at any RPM below 1000 RPM, then lag will be evident.
Mustang.101 is offline   Reply With Quote
Old 7th May 2011, 18:23   #34
Senior - BHPian
 
Join Date: Dec 2010
Location: Ghaziabad/Hyderabad/Mysore
Posts: 1,416
Thanked: 313 Times
Default Re: Turbo Lag 101

Quote:
Originally Posted by Mustang.101 View Post
For the Figo TDCi, anything above 1000 RPM will produce negligible lag, However if you are at any RPM below 1000 RPM, then lag will be evident.
Hi Mustang, you are back !

What I noticed was that on upshifting at speed, even when I fell below 100rpm (to 800-900 rpm, not lower) there was a good amount of pickup available.

On the other hand at similar rpm levels coming from the lower rpm levels (first gear) there wasn't that much power - this was experienced most in stop and go traffic.
vina is offline   Reply With Quote
Old 7th May 2011, 18:31   #35
BANNED
 
Join Date: Feb 2010
Location: New Delhi
Posts: 1,316
Thanked: 233 Times
Default Re: Turbo Lag 101

Quote:
Originally Posted by vina View Post
Hi Mustang, you are back !

What I noticed was that on upshifting at speed, even when I fell below 100rpm (to 800-900 rpm, not lower) there was a good amount of pickup available.

On the other hand at similar rpm levels coming from the lower rpm levels (first gear) there wasn't that much power - this was experienced most in stop and go traffic.
It could be one of the two things:

1. Road gradient.
2. Momentum of a fast car is more difficult to change.

Anyways it is not an issue with your car.
Mustang.101 is offline   Reply With Quote
Old 7th May 2011, 18:55   #36
Distinguished - BHPian
 
dhanushs's Avatar
 
Join Date: Oct 2009
Location: Bathery/BLR
Posts: 3,446
Thanked: 4,055 Times
Default Re: Turbo Lag 101

Quote:
Originally Posted by vina View Post
On the other hand at similar rpm levels coming from the lower rpm levels (first gear) there wasn't that much power - this was experienced most in stop and go traffic.
Ah..now I get it Vina... 2nd and 3rd gears ratios are more friendly towards roll-on torque than 1st gear in the Figo.
dhanushs is offline   Reply With Quote
Old 7th May 2011, 18:59   #37
Senior - BHPian
 
Join Date: Dec 2010
Location: Ghaziabad/Hyderabad/Mysore
Posts: 1,416
Thanked: 313 Times
Default Re: Turbo Lag 101

Quote:
Originally Posted by Mustang.101 View Post
It could be one of the two things:

1. Road gradient.
2. Momentum of a fast car is more difficult to change.

Anyways it is not an issue with your car.

Issue? I like it this is a "feature" if it is only my car.

Got an infection in the eye today, otherwise I would go out test it and tell you exact rpm numbers.

By the way, I'm very glad I bought Figo and not some other diesel (Swift, Tata ...) with pronounced power lag. I'm facing enough trouble stalling the car everywhere, in any other car I would have been in much more trouble.
vina is offline   Reply With Quote
Old 7th May 2011, 19:05   #38
Senior - BHPian
 
Join Date: Dec 2010
Location: Ghaziabad/Hyderabad/Mysore
Posts: 1,416
Thanked: 313 Times
Default Re: Turbo Lag 101

Quote:
Originally Posted by dhanushs View Post
Ah..now I get it Vina... 2nd and 3rd gears ratios are more friendly towards roll-on torque than 1st gear in the Figo.

that may be true - the first gear start growling at 1500 itself, 2nd and 3rd growl at 2000
vina is offline   Reply With Quote
Old 7th May 2011, 19:30   #39
BHPian
 
Join Date: Oct 2009
Location: RJ 14
Posts: 552
Thanked: 94 Times
Default Re: Turbo Lag 101

When turbo charger wakes up on 1500-200 RPM, why peoples say for few cars (like LINEA) almost NIL turbo lag? AFAIK zero turbo lag is impossible to achieve.
There is no use of turbo charger in initial pick up, TC improves HET (High End Torque) but if turbo awake on 1500-2000 RPM (almost in top gear 80 kmph) what is the use of turbo when vehicle is already going on good speed?
(Alok) is online now   Reply With Quote
Old 7th May 2011, 19:46   #40
BHPian
 
Skyline GT-R's Avatar
 
Join Date: Mar 2010
Location: Dubai
Posts: 594
Thanked: 202 Times
Default Re: Turbo Lag 101

I have driven my friends Swift & my new Figo recently & realized that in Swift the turbo lag & kick is pronounced, whereas in Figo only thing you do is to never allow the engine come down lower than 1500 rpm & you are fine.

In swift it is not possible to keep the turbo spooling during normal city driving.
Skyline GT-R is offline   Reply With Quote
Old 7th May 2011, 19:52   #41
Senior - BHPian
 
Join Date: Dec 2010
Location: Ghaziabad/Hyderabad/Mysore
Posts: 1,416
Thanked: 313 Times
Default Re: Turbo Lag 101

how does turbo lag effect mileage? at low rpm when the turbo is not spooling and I press the pedal completely, does the ECU force more fuel into the cylinders?
vina is offline   Reply With Quote
Old 7th May 2011, 20:00   #42
Distinguished - BHPian
 
Join Date: Mar 2011
Location: Back to Chndgrh
Posts: 2,203
Thanked: 2,956 Times
Default Re: Turbo Lag 101

Quote:
if I'm coming from a low rpm (say roughly 700, 800) into 1000 rpm, it takes several seconds before power develops.
Isn't this what is called turbo Lag ?
Turbanator is online now   Reply With Quote
Old 7th May 2011, 23:08   #43
Distinguished - BHPian
 
dhanushs's Avatar
 
Join Date: Oct 2009
Location: Bathery/BLR
Posts: 3,446
Thanked: 4,055 Times
Default Re: Turbo Lag 101

Quote:
Originally Posted by (Alok) View Post
When turbo charger wakes up on 1500-200 RPM, why peoples say for few cars (like LINEA) almost NIL turbo lag? AFAIK zero turbo lag is impossible to achieve.
I'm not sure who says 'zero' turbo lag, but then, there are some cars with negligible turbo lag.

A VGT, or Variable Geometric Turbo means, the boost pressure is avaialble at much lower rpm's and hence reducing turbo lag considerably.
Quote:
Originally Posted by (Alok) View Post
if turbo awake on 1500-2000 RPM (almost in top gear 80 kmph) what is the use of turbo when vehicle is already going on good speed?
For overtaking. Turbo charged engines have have considerably less 80-120kmph roll-on figures as compared to the Di ones.
Quote:
Originally Posted by vina View Post
how does turbo lag effect mileage? at low rpm when the turbo is not spooling and I press the pedal completely, does the ECU force more fuel into the cylinders?
Yes, vina, pedal to metal always means lesser economy. Whatever the speed/rpm. Well, if you have an OBD reader, you can see the instantaneous fuel consumption.

Last edited by dhanushs : 7th May 2011 at 23:09.
dhanushs is offline   Reply With Quote
Old 7th May 2011, 23:35   #44
Senior - BHPian
 
Join Date: Dec 2010
Location: Ghaziabad/Hyderabad/Mysore
Posts: 1,416
Thanked: 313 Times
Default Re: Turbo Lag 101

Quote:
Originally Posted by dhanushs View Post
...

Yes, vina, pedal to metal always means lesser economy. Whatever the speed/rpm. Well, if you have an OBD reader, you can see the instantaneous fuel consumption.

Hmmm I thought pedal controls the air flow while the ECU controls the fuel injection. I guess that may not be true.

Can I put OBD reader without voiding my warranty? also where do I get one for my Figo?
vina is offline   Reply With Quote
Old 8th May 2011, 00:22   #45
Distinguished - BHPian
 
dhanushs's Avatar
 
Join Date: Oct 2009
Location: Bathery/BLR
Posts: 3,446
Thanked: 4,055 Times
Default Re: Turbo Lag 101

Quote:
Originally Posted by vina View Post
Can I put OBD reader without voiding my warranty? also where do I get one for my Figo?
Yes, can get an OBD reader without voiding the warranty. The Figo's OBD port is somewhere beneath the steering. Its there to give us info, and hence will not void the warranty.

You can get cheap OBD readers tru ebay. They throw a hell lot of info, like Intake Air Temperature, Coolant temperature, throttle position, instantaneous fuel consumption, voltage across the terminals, pressure, speed, rpm and what not..

Here's a snap of heads up display on the windshield. You will need a symbian/android (preferably android) to read the values.
Turbo Lag 101-obd.jpg
dhanushs is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Turbo lag v/s Boost threshold Bookkeeper Technical Stuff 43 6th August 2015 23:39
BMW patents Electric Turbocharger - End of Turbo lag? Scorcher Technical Stuff 13 6th November 2011 19:59
Turbo lag on Vrs diven_b Technical Stuff 5 25th October 2008 00:26


All times are GMT +5.5. The time now is 23:33.

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