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Old 20th June 2009, 14:10   #1
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Default Do modern common-rails engines last like IDI/DI engines?

Hello,
Thanks for welcome note on my intro & obviously this was the question that a was posed, for me being an engine R&D engineer!

The typical answer `It depends'
The fact that these are new generation engine design-they are bestowed with better materials, better manufacturing process & control, better design evaluation etc. This gives CRDi engines better power delivery, fuel economy, exhaust emissions & reliability.

If we design a latest generation DI diesel, will it be better than the past DI diesels? Yes, it would. So the question will again be on an absolute scale is CRDI diesel better? My answer would be yes and for following reasons (addition to what i quoted above)
1) Smoother combustion : CRDi has a better control on rate of change of cylinder pressure making it smoother. While the overall pressures of latest engines are higher, they are designed to live with higher pressure! The smoothness of combustion make power train to work less harder!
Diesel fuel burns with a explosion inside the cylinder which is also uncontrolled. CRDI brings bit of control to this event
2) The fuel pressure is independant of engine speed: in ordinary diesel at low speed, fuel pressure is low while CRDI maintains higher pressure. This means even at lower speed the fuel injection is smooth & consistent making it a balanced combustion across all cylinders.
3) Since the combustion is smoother, engine mount/chassis etc see a lower level of vibrations
4) Engine can be tuned for a better spread of torque making it easier on transmission system

Now what can make CRDi poor -
a) higher injection pressure: injector & fuel line need to work at elevated pressure. If the design &/or manufacturing quality is poor on material, process & fit result is going to be bad
b) same is the case for piston/ring/liner
c) More electronics/Solenoid controls etc: while they are more reliable than mechanical system,they can be prone for damage from poor handling of electrical system (so no to roadside mechanics!)

We can go on, but I think, this gives us a direction. In nutshell a Modern CRDI is equal or better in reliability than a DI-diesel! So go on, buy that CRDi car!

Thanks to all
Gany
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Old 23rd October 2009, 01:19   #2
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[quote=Gany;1355122]Hello,

If we design a latest generation DI diesel, will it be better than the past DI diesels?

CRDI and Pump Duse are also a form of newer / latest generation DI engine.


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Originally Posted by Gany View Post
Hello,
Now what can make CRDi poor -
a) higher injection pressure: injector & fuel line need to work at elevated pressure. If the design &/or manufacturing quality is poor on material, process & fit result is going to be bad
b) same is the case for piston/ring/liner
c) More electronics/Solenoid controls etc: while they are more reliable than mechanical system,they can be prone for damage from poor handling of electrical system (so no to roadside mechanics!)

Thanks to all
Gany
Last year my friend bought a TATA Indigo DICOR. The Owner’s Manual booklet was common for both (Indigo TDI & DICOR). The compression ratio was 22:1 for TDI & same was 17:1 for DICOR.
b)Please explain why it is lower for DICOR, whereas DICOR/ CRDI engines have more pressurized fuel injection?
C)seen many vernas, taveras even scorpio and safaris with exhausting huge black smoke (probably it is because of problematic EGR valve). Defiantly road side mechanics are no no.
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Old 23rd October 2009, 08:38   #3
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They seem to be holding strong. We went in an Innova that had done 1,55,000 kms to Pondy. It was running like any new Innova would.
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Old 23rd October 2009, 11:09   #4
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Quote:
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They seem to be holding strong. We went in an Innova that had done 1,55,000 kms to Pondy. It was running like any new Innova would.
something about these toyota engines - they never seem to age. I have seen a few Qualis which have done more than 2.5 lakh kms and are still going strong!
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Old 23rd October 2009, 11:58   #5
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In the long term, you will find that due to higher pressures, injection pumps wear out faster, bearings wear out. Higher pressures and heat will see injectors fuse to the cylinder head. You need to remove these and put back now and then to avoid this.

Add longer oil change intervals and that crdi engine will be a liability and maybe the second hand petrol could be the better option
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Old 24th October 2009, 21:35   #6
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Quote:
Originally Posted by harsha.cs1 View Post
something about these toyota engines - they never seem to age. I have seen a few Qualis which have done more than 2.5 lakh kms and are still going strong!
That's nothing. There are 2 Mitsubushi Lancers which have completed 5 lakhs KM in Vizag and they still start in first crank early morning and run like new. And those are non-CRDi, non-Turbo engines mind you. Mitsu engines are most bullet proof diesel engines i have seen.
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Old 24th October 2009, 23:01   #7
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Engine life is not an issue with modern CRDi engines, they last long enough, in many cases as long as a modern petrol.
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Old 24th October 2009, 23:19   #8
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1) The present generation of engines are reliable and run for quite a distance. Over 1 lakh km is not a impossible. Specific mention of Innova engine. The engine is very very reliable and runs on and on. I have personally seen some Innova Taxi do over 2 lakh kms. and still its going strong.

2) The end results IMO depend upon manufacturer. Accent CRDi was the one in which I have seen some problems cropping up, but the Verna CRDi is not problematic. The reliability and longevity of common rail engines vary from manufacturer to manufacturer. But in general they do last long.

3) The last fact IMHO is maintenance. If something goes wrong with critical componts of CRDi motor, then its more expensive to maintain. This is a negative point of CRDi motors. Next is that they are inherently more complex than DI motors. CRDi equipped cars are best away from local mechanics unless the mechanic is very knowledgeable.


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Originally Posted by (Alok) View Post
Last year my friend bought a TATA Indigo DICOR. The Owner’s Manual booklet was common for both (Indigo TDI & DICOR). The compression ratio was 22:1 for TDI & same was 17:1 for DICOR.
b)Please explain why it is lower for DICOR, whereas DICOR/ CRDI engines have more pressurized fuel injection?
C)seen many vernas, taveras even scorpio and safaris with exhausting huge black smoke (probably it is because of problematic EGR valve). Defiantly road side mechanics are no no.
Have a look at this thread. This thread mentions most of the aspects of DICOR engines. To me, Dicor is not better in practical real life than TDi. Dicor has realibility issues, though not major, but they are not as good as TDi.
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Old 24th October 2009, 23:28   #9
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@aaggoswami - Accent CRDi has the engine with least engine life amongst the crdi s, i have seen a lot cars in my friend circle giving up after 70-80k kms. But apart from this car most common rails are very reliable, I know Elantra diesels with 2lakh+ kms, even my own car has done 125k kms and is as good as when it was new.
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Old 25th October 2009, 00:04   #10
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[quote=(Alok);1544639]
Quote:
Originally Posted by Gany View Post
Hello,

Last year my friend bought a TATA Indigo DICOR. The Owner’s Manual booklet was common for both (Indigo TDI & DICOR). The compression ratio was 22:1 for TDI & same was 17:1 for DICOR.
b)Please explain why it is lower for DICOR, whereas DICOR/ CRDI engines have more pressurized fuel injection?
I'm no expert on the Indigo engine, but having studied about the IC engine in general, I can think of the following reasons for your observation:

(a) The temperature/pressure required for ignition is a factor of the mixture strength as well as spray pattern.

(b) In a DICOR engine, since the fuel is pressurised, the spray pattern is likely to be much finer and at the same time the size of the atomized fuel particles are also likely to be much smaller. Both these factors will also enable a mixture which is closer to the design/stoichiometric value.Both these factors will ensure easier and better combustion. Hence it is possible that ignition takes place at a lesser pressure as compared to a non DICOR engine which will explain the lower compression ratio.

Probably the Gurus can shed mire light on the matter!
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Old 12th September 2010, 21:44   #11
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1) Lancer Diesel 2.0 IDI is the best engine in India when longevity is concerned. It is still selling at Rs.7.75 lakh ex-showroom Chennai.

2)Toyota diesel- definitely IDI better than DI. Qualis engine is more reliable than innova's
But the above conclusion may also have to do with fuel quality issues in India.

3)Tata: No comments, as their engines are evolving with time.

4)Ford: 1.8 IDI NA is solid reliable motor. 1.4 TDCi is safe until 1 lakh kms, i am often hearing this.

5)Fiat: the 1.7 IDI in the Uno motor had seen 3L kms. 1248cc CRDi is something i have always looked down, yet one user have reported 2L km(in swift).

6)Scorpio: 2.6 turbo long lasting than the 2.6 CRDi.

7)Proven IDIs, DIs, and then CRDis- this is the ranking order.

8)What i am trying to say is, in the past(IDI era) engine heaviness is responsible for engine reliability. Simple mechanics is always reliable than sophisticated electronics.
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Old 12th September 2010, 22:00   #12
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Interesting point, I would like to know the views. My old DI (Mahindra Bolero Camper, 2002) had done 8.5 lakh kilometres before going in for a rebore. Hypothetically speaking, can CRDI engine with same block (or with required modifications) can give such a long life?
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Old 13th September 2010, 19:50   #13
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I'm not sure if 400,000 km Innovas should be the yardstick. For one, it's a 10 lakh MUV and second, a Toyota.

Really keen to see how things pan out with the 3 - 6 lakh rupee common-rail diesels in the longer term. How does the fuel pump hold up? The turbo-chargers? If it helps, some Swifts have already crossed 1.5 lakh kms without issue. I guess we'll know in another 3 - 4 years (by which time all of the recent launches would have logged on the kms).

P.S. Remember, if you want to maximise the life of your diesel, keep those revvs low. No point hitting the 4,500 rpm redline everytime you are out on the highway. Work the torque!
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Old 13th September 2010, 20:27   #14
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Ok What i am about to post is not at all a technical view or facts but what i have ben told by the Taxi Stand operator who takes fuel from us.

His fleet consists mostly of Indigo's, Indicas, followed by Innovas and new additions are the Swift dzire diesel and a couple of Xylo's. He told me that he keeps the Tata cars for 2 years only and finances them on 2 year loan plans He utilizes them for 2 years and sells them off then, as he says that isues start cropping up by then and he never gets the engine overhauled he chooses to dispose of the car before the car requires work, On an average his cars clock 10000 Km a month so by 2 years its 2lakh kms+ on the odo, thats when he sells the Tata's

The Innova on the other hand he finances for 3 years and sells of after 3 years after they clock about 3.5 lakh Kms on the Odo, his innovas till date have never let him down in the 3 years of ownership and all thats required is Regular service which in his case happens every month . His Cars are pretty well maintained and his drivers are penalized if the car doesnt give decent mileage on highway runs so the drivers are forced to drive at 80-90kph.

He has no Mahindra product apart from the Xylo which is about 6 months old and has clocked 66000 kms last time i checked.
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Old 13th September 2010, 20:50   #15
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In my experience, the life of engine depends on its deisgn and build, materials involved etc. Though Crdi is sensitive to poor fuel and mishandling of electronics which controls it, It depends on manufacturer.

But my 1999 lancer is still running with single crank after its Odo reading 4,24,000 kms. But i dont find any serious issues with mitsu engine, but i have to admit that it is not powerful as modern diesels, but its solid. I had also owned an esteem fitted with Toyota 1N diesel, My vote for Japanese diesels.
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