Guide: How To Drive and Maintain a Diesel Car?

[tdcarlover]

In bumper to bumper traffic i stay in 1st gear and the torque of the diesel pull along with no accelerator needed Also, i avoid clutch riding and get better clutch life this way.
After 1800-2000 rpm while the turbo spools up your mileage also drops. I try "turbo power" mostly to get to speed on highways and then on 5th gear stay ~1800 RPM-decent speed and decent mileage

 

[Figoian]

After 1800-2000 rpm while the turbo spools up your mileage also drops.

I couldn't understand this point. Why would the mileage drop with turbo spooling in?

 

[incarnation]

i mean when you have a turbo vehicle the turbo has to be spooled right may be unnecessary revving beyond 3k might result in mileage drop but not because of turbo spooling in at 2k rpm that's for sure

 

[Figoian]

i mean when you have a turbo vehicle the turbo has to be spooled right may be unnecessary revving beyond 3k might result in mileage drop but not because of turbo spooling in at 2k rpm that's for sure

I think, you don't necessarily have to revv it till 3K, rather can control your throttle.

In diesels, being on the power band, i.e. turbo zone gives you the best performance and efficiency.

 

[incarnation]

@ figoin the inference of saying that was until and unless your rpm is under 3k thers no chance of mileage drop

 

[tdcarlover]

Recently a thread on the Limca record for mileage was on a Manza Q-jet in TAI. The RPM to achieve was around 1500. Well that also translates ~50k speed.
I agree turbo make a small engine more powerful and efficient. At what rpm is this most efficient and when does it consume more? Reviews on the net say it depends on many things!
I feel 1800 is when i get the max mileage with reasonable speed as well

 

[Figoian]

I agree turbo make a small engine more powerful and efficient. At what rpm is this most efficient and when does it consume more? Reviews on the net say it depends on many things!
I feel 1800 is when i get the max mileage with reasonable speed as well

IMO, it's where the peak torque is produced.

Recently a thread on the Limca record for mileage was on a Manza Q-jet in TAI. The RPM to achieve was around 1500. Well that also translates ~50k speed.

Yes, it's Mr. Narayanan Menon. However, I doubt how RPM of 1500 can achieve best mileage Fiat's Q-Jet spins the turbo only after 2K RPM.

 

[Swapnil]

Yes, it's Mr. Narayanan Menon. However, I doubt how RPM of 1500 can achieve best mileage Fiat's Q-Jet spins the turbo only after 2K RPM.

You mean it fully spools up only after 2000 RPM.
As far as fuel economy is concerned, yes, driving on highways at RPMs as low as 1500-1700 can give you very good figures.

 

[Figoian]

You mean it fully spools up only after 2000 RPM.

Yes. AFAIK, turbo kicks in only after 2K RPM in Fiat Multijet.

As far as fuel economy is concerned, yes, driving on highways at RPMs as low as 1500-1700 can give you very good figures.

So, isn't that the Turbo isn't utilized at all? Then how can the engine perform to optimum level?

 

[Swapnil]

So, isn't that the Turbo isn't utilized at all? Then how can the engine perform to optimum level?

It is utilized, but not fully. The full spool comes at the 2000 RPM mark.

 

[incarnation]

@ swapnil even i have the same question like figoian and even i think that the turbo comes into action only after 2k rpm please throw some light on this would like to know more

 

[tdcarlover]

Says Narayan Menon in an interview "rpm b/w 1300 – 1600, I maintained somewhere b/w 1440-1500" is how he got that mileage.
If you combine that fact with the manza's turbo figures- " torque comes in at 1,750 rpm, (turbo seems to really start spooling only after 1,800)" it would appear that the less the turbo the better the mileage.
This however seems to turn the logic of having a turbo diesel to increase efficiency (mileage) on its head-i am confused

 

[Swapnil]

When you turn on the engine, the turbo starts rotating. However it does not put 'considerable' amount of air into the engine, as there is not enough exhaust gas pressure built up yet (you're at those lowly 1400-1600 RPMs).
When enough exhaust gas pressure is built (RPM > 2000), it starts putting 'considerable' (read as full spool, turbo kick) amounts of air, and that is when you get high on power.
Whenever I drive on highways in that 1500-1600 band, I too get very good F.E.

 

[incarnation]

in such a scenario Wat would be the difference between a vehicle which has turbo and which doesn't have turbo. I think both would be high on mileage then why waste extra money on turbo for better FE. Some info Reqd if im wrong

 

[TSIVipul]

I couldn't understand this point. Why would the mileage drop with turbo spooling in?

AFR(Air-Fuel ratio) is the answer to your query.

Turbocharging means higher density of air in cylinder and hence a higher amount of fuel is required to maintain the right AFR.