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Old 6th December 2010, 00:07   #31
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Since the original poster's query was about the Indigo TDi, which is a small capacity diesel that doesn't have much low-end torque, it would be futile to shift before the turbo kicks in. I find that the easiest way to get good economy and still keep the turbo on the boil coincide. Just shift up at or just after the max torque rpm, which is around 2400. Shift down the moment the engine starts to 'boom'. I find that this works for the Multijet engine as well.

For higher capacity engines, they develop decent amounts of torque even before the turbo has spooled up, and upshifts can be made earlier. I think the golden rule is to listen for engine 'boom' and shift up at or after peak torque rpm.

The recommended upshift speeds for the diesel Indigo is higher than that for the petrol version, as given in the sticker on the windscreen.

Gear Diesel Petrol
1 15 10
2 25 20
3 45 30
4 60 40
5 70 50

Unsurprisingly, I found that shifting at those speeds did result in no engine 'boom' and good throttle response.
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Old 6th December 2010, 11:00   #32
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Quote:
Originally Posted by dhanushs View Post
When I test drove the Manza too, there was no Turbo, forget the lag. Also, the vehicle was yet to under go PDI.

This makes me doubt; can the turbo be deactivated/detuned for minimal turbolag(by dealers)?. Does the ECU have a role in switching on/off the turbo, with regard to engine RPM, rather than exhaust pressure only? (As the speedo on test vehicle was deactivated) .

That way, can the dealers convince the ignorant buyers about the infamous turbolag?.
Manza has a Turbocharger FYKI.

As Far as I know, Turbocharger cannot be deactivated or detuned.

Quote:
Originally Posted by mile201 View Post
This may be a little off-topic but is there a difference between the amount power produced by a turbocharged engine before the turbo kicks in and the same engine in non turbo form at the same RPM. I heard somewhere that turbo engines are tuned in such a way that they produce less power than an identical NA engine before the turbo starts producing boost...does this make sense?
I have long back TD an Indica DLS which was not fitted with Turbo.
At that time the throttle response of that Indica and our Indigo IDI (not TDi) were identical below 2000-2500rpms.
In Indigo there is Turbo. Hence the response of the engine is more than that of Indica at 2000-2500rpms.

Quote:
Originally Posted by vivekgk View Post
Since the original poster's query was about the Indigo TDi, which is a small capacity diesel that doesn't have much low-end torque, it would be futile to shift before the turbo kicks in. I find that the easiest way to get good economy and still keep the turbo on the boil coincide. Just shift up at or just after the max torque rpm, which is around 2400. Shift down the moment the engine starts to 'boom'. I find that this works for the Multijet engine as well.

For higher capacity engines, they develop decent amounts of torque even before the turbo has spooled up, and upshifts can be made earlier. I think the golden rule is to listen for engine 'boom' and shift up at or after peak torque rpm.

The recommended upshift speeds for the diesel Indigo is higher than that for the petrol version, as given in the sticker on the windscreen.

Gear Diesel Petrol
1 15 10
2 25 20
3 45 30
4 60 40
5 70 50

Unsurprisingly, I found that shifting at those speeds did result in no engine 'boom' and good throttle response.
Thanks for the clarification in Bold.


Vivek the speeds which are printed on the sticker on the windscreen are for getting Max. FE. Read the title of the sticker.
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Old 7th December 2010, 12:26   #33
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Quote:
Originally Posted by IndigoXLGrandDi View Post
Manza has a Turbocharger FYKI.
Manza has a VGT - probably this explains the reason why there is no "kick" at the back feel when you accelerate hard !
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Old 8th December 2010, 17:37   #34
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Default re: When do you shift gears?

I donot see the tacho while upshifting or downshifting. I do on basis of the engine power. You have to be bit fast in releasing the clutch offcourse smoothly when you upshift early to avoid lugging but be relaxed in releasing the clutch when you upshift at higher rpms.

Better to stick to manufacturer recommendations and do a + or - 10km speed here and there.
But if done correctly, definitely the life of the engine and turbo charger will be more.
I shift to 4th at 40km with two adults - all shifting done < 2500 rpm in my Figo TDCi.
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Old 9th December 2010, 12:37   #35
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Question re: When do you shift gears?

Sorry.
The way of asking the question was wrong.

I wanted to know whether it is necessary to use the Turbo everytime while upshifting.

If the Turbo is not used while upshifting what is the use of a Turbocharged Engine?

If I am correct, the Turbo is being fitted by Manufacturer to lower Emissions. The Turbo uses some of the Exhaust Gases and provides power to the engine thereby reducing the emissions.
So if the Exhaust Gases are not given back to the engine, how will the emissions be lowered?

Sorry for not asking the question correctly.
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Old 9th December 2010, 15:54   #36
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Default re: When do you shift gears?

Quote:
Originally Posted by IndigoXLGrandDi View Post
Sorry.
If I am correct, the Turbo is being fitted by Manufacturer to lower Emissions. The Turbo uses some of the Exhaust Gases and provides power to the engine thereby reducing the emissions.
So if the Exhaust Gases are not given back to the engine, how will the emissions be lowered?

Sorry for not asking the question correctly.
I beg to differ here..

1) The turbocharger doesnt serve any purpose in lowering emissions. It is used to increase the flow of air to the engine and therefore increase power.

2) The turbocharger runs from the exhaust gas pressure, but the air being fed to the engine is fresh air. The turbine and compressor blades are mounted on the same axis, but have totally disconnected air flow paths.

The exhaust gas , once it passes through the turbine, goes through the cat converter, muffler ( not sure about the order here ) and then to the atmosphere. The intake gas is fed to the compressor directly from the air, through the air filter.

At least this is what I understand about how it works.. Experts can add more/correct!
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Old 9th December 2010, 17:40   #37
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Default re: When do you shift gears?

I believe more air = better combustion, and hence less soot, NOx etc
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Old 12th December 2010, 15:06   #38
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Default re: When do you shift gears?

Means if a Turbocharged Engine is driven sedately, there is not considerable increase in exhaust gases as compared to when it is driven at high rpms (due to exhuast gases recirculating back to Turbo), right?

If its so, I will upshift early when driving sedately and make use of Turbo only when I need that Boost.
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Old 8th June 2011, 21:56   #39
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Exclamation How do you shift gears? Engine Noise and Vibrations : Tachometer : Instincts !

Hi BHPians,


When we learn driving, we don’t have a clue when a gear needs shifting and during that time shifting gears is just a formula i.e. X RPM + Speed = X gear. Eventually after we have driven for some time, we get the hang of it and know how to shift properly.

Now as we have learnt how to shift gears here is the question:

How do you shift gears? What makes you think that it is the right time to up shift or downshift?

Do you look at the tachometer needle to cross a certain RPM ? Or do you listen to the engine sound and then shift?

Or are you like me, for whom shifting gears comes naturally where your subconscious does the shifting without your knowledge.


And one more thing, if you don’t use the tachometer for shifting, when do you use it? Or do you use it at all?


Mods:
I searched around and couldn’t get a thread that discusses this aspect of shifting gears, If there is one please merge this with the existing one.

Can we also add a voting buttons for the same ?

Last edited by aah78 : 8th June 2011 at 22:34. Reason: Thread merged with existing.
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Old 9th June 2011, 00:16   #40
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Default Re: When do you shift gears?

As people discussed in the thread, ideal upshifting should be done at 2000-2500rpm. But I for one never look at these [though I have a RPM meter in my car]. I usually upshift / downshift based on speed of the car. There are at times I upshift at 1500 rpm as well. Since my car is a diesel with turbo, early upshift helps me reduce the lag. In the petrol ones, again I go for a speed based upshift.
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Old 9th June 2011, 00:38   #41
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Default Re: When do you shift gears?

Quote:
Originally Posted by swiftnfurious View Post
There are at times I upshift at 1500 rpm as well. Since my car is a diesel with turbo, early upshift helps me reduce the lag.
The turbo kicks in at 2k RPM. So, how does shifting up at 1.5k RPM reduce the turbo lag?
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Old 9th June 2011, 00:56   #42
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Default Re: When do you shift gears?

Quote:
Originally Posted by Klub Class View Post
The turbo kicks in at 2k RPM. So, how does shifting up at 1.5k RPM reduce the turbo lag?
The upshift at 1500 rpm was a general statement [and not in respect to the turbo lag]. I try and upshift 2 & 3 gears very early and the car doesn't feel strained / slow [the car doesn't feel running out of steam]. I am not a techie - so dont know how to explain it, but the explanation to reduce lag by upshifting early is provided in some thread - may be the same one. Will have to dig a bit deep.
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Old 9th June 2011, 00:57   #43
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Default Re: How do you shift gears? Engine Noise and Vibrations : Tachometer : Instincts !

Quote:
Originally Posted by MadTiger View Post
How do you shift gears? What makes you think that it is the right time to up shift or downshift?
===========
Do you look at the tachometer needle to cross a certain RPM ? Or do you listen to the engine sound and then shift?
Each engine has its unique power band, and hence propels the car in a different way in each gear. Use the gear which you think would most efficiently propel the car, aka, let the engine be in its power band. Once you make this a practice, there is no need to tacho, or sound or speed.
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Old 11th June 2011, 18:39   #44
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Default Re: When do you shift gears?

By my question remained unanswered.
Is it compulsory to let the Turbo spool in every gear?
Letting the Turbo spool will increase or decrease the life of engine and Turbo?
Also if the RPM is increased such as to spool the Turbo, the soot formed will be less, then will the emissions be less or not?
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Old 12th June 2011, 12:26   #45
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Default Re: When do you shift gears?

Quote:
Originally Posted by MadTiger View Post
How do you shift gears? What makes you think that it is the right time to up shift or downshift?

And one more thing, if you donít use the tachometer for shifting, when do you use it? Or do you use it at all?
Quote:
Originally Posted by dhanushs View Post
Each engine has its unique power band, and hence propels the car in a different way in each gear. Use the gear which you think would most efficiently propel the car, aka, let the engine be in its power band. Once you make this a practice, there is no need to tacho, or sound or speed.
In addition to what Dhanush said, you also need to consider the road conditions while deciding the gear shift. Eg. If you are in slow moving traffic and everyone starts moving after a halt; it wouldn't do good to upshift to 3rd just because you've gained momentum. Another pile up might get you to downshift to 2nd. Frequent gear shifts won't help either your FE or your clutch.

About the tachometer, it is to show you the rpm the engine runs at; if you're technologically advanced, there is quite a bit it could be useful for. And of course, the tachometer needle will give you some pleasure at high speeds!
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