Guide: How To Drive and Maintain a Diesel Car?

[TSIVipul]

Re: How To Drive and Maintain a Diesel Car?

Turbocharger is running at all rpms. A turbocharger is a high precision piece of engineering. And it starts rolling at slightest gust of exhaust gases. But the pressure developed by it is significant enough only at around 1800 rpm (or above this rpm).

Thanks for correcting buddy,I'll be remembering this from now onwards.

You are right Vipul. "Cranking" means turning the crankshaft of the engine with external aid (by starter motor). Sometimes its done by pushing the car. Cold start is just a condition. You still have to crank it to bring it to life.

In other words when we push start the vehicle,the gearbox works as the 'external aid' that time.Right?

Not true for all diesels. Yes, in my Punto, the low end is terrible. But in mHawk, TDi, D-4D, etc... even the low end is great. Just that, you wont get the kick of the turbo, but it wont be lethargic.

Yeah it is better than the Honda i-vtec and Maruti Suzuki 'K' series engines in low end.Other petrol engines are still having better low end pull.

To overcome turbo lag, all you have to do is be in the right gear at the right time. Its not a big deal as it sounds!

+100,turbo lag is really nothing,you just need to know how to work the gearbox.

For example, Innova & Punto. You have driven both. Punto needs more gearshifts than Innova.

This depends on the powerband.Punto's engine is good at higher middle range while Innova takes the beating there.And any car which is having powerful top end but less powerful lower end always needs a lot of gearshifts.Especially while moving below 60 kph or in city.

There is nothing wrong in what you are doing buddy. Only thing is, you turbo must be in hibernating mode now, since you have rarely used it!

Once in a while, you do need to rev it. Dont unnecessarily keep revving it for long durations. Dont even rev it till 4000 rpm. Short bursts till 3000 rpm once in a while will also do. You have a turbo diesel, use the turbo !!!

+100,I was also trying to explain the same to him..

 

[raj_5004]

I beg to differ Raj. As you said cranking was done earlier to start the engine, using a handle. That lever has been replaced by starter motor. I feel it has to do with starter motor, or any device or means which is used to turn a engine for starting purpose.

Thanks

I was actually telling him the meaning of the word 'cranking' and its origin and not what it's related to.

@ depress clutch means we have to press clutch when starting the car?

Yes, depress clutch means press the clutch pedal which in turn means engaging the clutch which in turn detaches the gearbox from the crankshaft.

Sorry for confusing you! Do ask if you have more queries.

Nice work Raj!

Thank you buddy.

 

[Superbad]

Turbocharger is running at all rpms. A turbocharger is a high precision piece of engineering. And it starts rolling at slightest gust of exhaust gases. But the pressure developed by it is significant enough only at around 1800 rpm (or above this rpm).

so what is the difference between variable geometry turbo VGT and FGT fixed geometry turbo.
I believe the scorpio,XUV500,sx4 diesel and punto,linea 90hp has VGT whereas the 75hp Mjd are FGT.

 

[TSIVipul]

so what is the difference between variable geometry turbo VGT and FGT fixed geometry turbo?
I believe the scorpio,XUV500,sx4 diesel and punto,linea 90hp has VGT whereas the 75hp Mjd are FGT.

I have been asking same question for a long time and in fact many people answered it..but I am yet to understand the difference..

Scorpio has got a FGT while the XUV has got a VGT as much I know.

 

[jayadev]

for my car i never faced issue of turbo lag .



I always drive it below the turbo threshold.

I havent understood yet why they need to have a turbine in all the diesal cars.

___________________________________________________________________

we have two ford rangers. both 2.4 litre one is tdci and one is NA.

the one without turbo is nice and smooth to drive and very much fuel efficient than the tdci.
one with tdci is silent and refined and shoots like a rocket after 2k rpm.

Tdci was proved very dear to maintain,turbine failed twice and other engine ,ecu problems.

both hav run 1lakh+ km

Tdci :10-11 kmpl

Na :13-15kmpl

 

[Superbad]

Scorpio has got a FGT while the XUV has got a VGT as much I know.

i am not sure but from whatever i have read from the reviews it states that from the 2009 refresh models have the VGT

 

[Sam Dinkar]

for my car i never faced issue of turbo lag .



I always drive it below the turbo threshold.

I havent understood yet why they need to have a turbine in all the diesal cars.

___________________________________________________________________

we have two ford rangers. both 2.4 litre one is tdci and one is NA.

the one without turbo is nice and smooth to drive and very much fuel efficient than the tdci.
one with tdci is silent and refined and shoots like a rocket after 2k rpm.

Tdci was proved very dear to maintain,turbine failed twice and other engine ,ecu problems.

both hav run 1lakh+ km

Tdci :10-11 kmpl

Na :13-15kmpl

Not getting too technical here, just understand that the combustion characteristics of diesel are much different from those of petrol and therefore (and also due to certain other factors) a diesel engine of, say 1000cc shall always develop lesser Bhp than a petrol 1000cc engine while the torque of the 1000cc diesel engine shall indeed be higher. To overcome this inherent lacunae, the easiest way to significantly increase the power of a diesel engine (or of a petrol engine) without increasing it's cubic capacity (more cc = more weight = more space in the engine bay = more excise duty = more fuel consumption = less sales ) is to install a tubrocharger (which is a device to recirculate the hot exhaust gases into the combustion chamber, thereby improving combustion characteristics and giving more power).

 

[jayadev]

(more cc = more weight = more space in the engine bay = more excise duty = more fuel consumption = less sales ) it to install a tubrocharger (which is a device to recirculate the hot exhaust gases into the combustion chamber, thereby improving combustion characteristics and giving more power).

I get it.
equivalent power from a comparatively smaller motor.
hmm.

 

[nozzlering]

Vipul, I will try to explain you the difference between FGT and VGT.
Basic principle of a turbocharger in layman's term. A turbine is directly coupled to a compressor(blower). Exhaust gases make the turbine rotate, which in turn rotates the blower. This blower compresses the intake air and supplies air in excess to combustion chamber. The exhaust gases are introduced to the turbine blades via a set of nozzles. The angle of these nozzles determine the gas pressure. More pressure, faster the turbine will rotate and vice versa.
When the angle of nozzles is fixed it is FGT. In FGT max power and efficiency range is limited.
But latest technology is that the angle of nozzles can be varied on the basis of external factors. In this case, max power and efficiency range is more widespread.

 

[Superbad]

I was explained in laymans term that turbo Chargers introduce nitrogen (NO) in the combustion chamber. Is it right or incorrect?

 

[nozzlering]

INCORRECT. Turbochargers utilise waste exhaust gases to optimise combustion, hence improve efficiency and power output. NO has nothing to do here.

 

[Raja]

Ok guys first extremely sorry if iam talking something silly or making silly comparisons so far what I have understood about turbo lag in cars is
Lets take example of Scorpio and safari , people say scorpio is easy to drive in city does it mean that if you are at 40kmh on 3 gear and you brake and the speed comes to 20 you can still continue driving without shuddering the Scorpio and then slowly build the speed to 50 and then shift to 4th gear ?

But if the same example happens with safari you have to downshift on 2 gear then again build the speed to 40 upshift to 3 then 50 and 4th because if you don't the safari will shudder and may stall ? Can some 1 answer this please
.
Raj thanx for creating this thread this will be of immense help for the members and you vipul and others are doing great job and will be great if you guys can give some real world examples like the one raj and vipul gave about turbo lag and other topics which will pop in it gives a better understanding and more easy to grasp alongbwith technical words.

 

[jihu123]

Nice Thread. Anyone can give me info on the petrol & diesel engine maintenance costs? Why do people always say that diesel is only good if you drive daily for about 50kms?

You are right. In many modern diesel cars, you cant start the car unless you completely depress the clutch. My Manza has this feature.

The Micra is just the opposite. If you need to start the engine by using the start/stop button, then you gotta completely press the clutch!

Ok guys first extremely sorry if iam talking something silly or making silly comparisons so far what I have understood about turbo lag in cars is
Lets take example of Scorpio and safari , people say scorpio is easy to drive in city does it mean that if you are at 40kmh on 3 gear and you brake and the speed comes to 20 you can still continue driving without shuddering the Scorpio and then slowly build the speed to 50 and then shift to 4th gear ?

Yeah. That's what they meant. Scorpio has a good low end torque & even the Innova goes smooth at 40km/h on 4th gear!

But if the same example happens with safari you have to downshift on 2 gear then again build the speed to 40 upshift to 3 then 50 and 4th because if you don't the safari will shudder and may stall ? Can some 1 answer this please

This might be mainly due to the less low end torque of safari or maybe something else. Waiting for the experts to answer!

 

[Markiv]

Thank you very much raj for sharing this knowledge of yours. It is very informative. Thanks also to vipul, nozzle ring and others for putting their pie in. Jayadev 's query is more or less mine and hence I have got my reply. Jihu, pressing and depressing are the same..just that pros speak in a different lingo and we amateurs in another lingo.

 

[raj_5004]

so what is the difference between variable geometry turbo VGT and FGT fixed geometry turbo.
I believe the scorpio,XUV500,sx4 diesel and punto,linea 90hp has VGT whereas the 75hp Mjd are FGT.

See buddy, the word itself is self explanatory.

In fixed geometry turbo, the geometry of the turbo is fixed. In technical terms, it is called aspect ratio. So what happens is, if the aspect ratio is too large (big turbochargers), the turbo will be useless at lower rpm whereas if the aspect ratio is too small (small turbochargers), the turbo will be useless at higher rpm.

To solve this problem, VGT was used. It has these movable vanes which can direct exhaust flow onto the turbine blades. These vanes are electronically controlled via an actuator. So when the engines are running at lower rpm, these vanes leave very little gap for the exhaust gases to flow. This pressure accelerates the gases thereby rotating the turbine faster. At higher rpm, these vanes open fully. So, VGT is always on the spool, at lower rpm & even at higher rpm, unlike FGT.

This is the technical difference. Real world difference would be that you will not encounter any noticeable turbo lag in engines with VGTs.

I hope I was clear. Please tell me if you want me to go more easy on the words.

Scorpio has got a FGT while the XUV has got a VGT as much I know.

No buddy... all mHawks have VGTs, even Scorpio.

i am not sure but from whatever i have read from the reviews it states that from the 2009 refresh models have the VGT

Even pre refresh Scorpios had VGTs.

Lets take example of Scorpio and safari , people say scorpio is easy to drive in city does it mean that if you are at 40kmh on 3 gear and you brake and the speed comes to 20 you can still continue driving without shuddering the Scorpio and then slowly build the speed to 50 and then shift to 4th gear ?

But if the same example happens with safari you have to downshift on 2 gear then again build the speed to 40 upshift to 3 then 50 and 4th because if you don't the safari will shudder and may stall ? Can some 1 answer this please
.

Correct. That is because Safari has more turbo lag than Scorpio.

Nice Thread. Anyone can give me info on the petrol & diesel engine maintenance costs? Why do people always say that diesel is only good if you drive daily for about 50kms?

Diesels are not too expensive to maintain either.

Why people say the "50 kms" thing is because a typical diesel car would cost atleast a Lac more than its petrol counterpart. So, to breakeven this additional one Lac that you have spent, you have to drive atleast 40-50 kms a day. By the end of 2-3 years, you would have utilized that additional money.

The Micra is just the opposite. If you need to start the engine by using the start/stop button, then you gotta completely press the clutch!

Depressing the clutch means pressing the clutch.