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Old 1st February 2009, 22:01   #46
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Originally Posted by Ravveendrra View Post

CRDi, CRDe, DICOR, etc. etc. are all the self-same CDI introduced by Mercedes Benz and Bosch. The only new advance in Diesel engines is the 'MultiJet' introduced by Fiat, the Maruti-Swift engine is manufactured by Fiat.

])

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Wait for the folks with intimate knowledge about Fiat to wake up with clarifications
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Old 2nd February 2009, 01:05   #47
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Quote:
Originally Posted by Ravveendrra View Post
CRDi, CRDe, DICOR, etc. etc. are all the self-same CDI introduced by Mercedes Benz and Bosch. The only new advance in Diesel engines is the 'MultiJet' introduced by Fiat, the Maruti-Swift engine is manufactured by Fiat.
Is DDiS / Multijet / Quadrajet technology any different from CDi, CRDi etc? Please elaborate.
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Old 2nd February 2009, 13:34   #48
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Quote:
Originally Posted by SS-Traveller View Post
Is DDiS / Multijet / Quadrajet technology any different from CDi, CRDi etc? Please elaborate.
Quote:
The only new advance in Diesel engines is the 'MultiJet' introduced by Fiat, the Maruti-Swift engine is manufactured by Fiat.
Don't let the names confuse you. In principle, multijet is the same as common-rails. It's only manufacturers who call the technology differently (Hyundai - CRDi, Merc - CDI, Tata - Quadrajet, Fiat - Multijet etc. etc.).
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Old 2nd February 2009, 15:19   #49
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Originally Posted by GTO View Post
Don't let the names confuse you. In principle, multijet is the same as common-rails. It's only manufacturers who call the technology differently (Hyundai - CRDi, Merc - CDI, Tata - Quadrajet, Fiat - Multijet etc. etc.).
That's what I thought too, but got the impression that it is otherwise. Thanks GTO.
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Old 2nd February 2009, 22:47   #50
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Default CDI is the genus, Multijet is the species

Yes GTO and SS-traveller, you are right in a way. The MultiJet is a CDI engine but, with a twist in the tail.

The difference between other CDI units and the Multijet (which is owned by Fiat & GM) is that the Multijet electronically controls the injectors to spray the fuel in short bursts (5 bursts if I remeber correctly) in each cycle, whereas the others inject the fuel in one shot. Fiat & GM claim that this means quieter combustion, minimised vibration, reduced emissions, better performance and improved FE.

Fiat and GM call the Multijet engines as JTD, Tata calls it Quadrajet and Suzuki calls it DDIS.

As far as I could make out, the differnce between CDI (CRDI, CRDE etc.) and Multijet is in the number of times the fuel is injected in each cycle of the piston.

Material on this is difficult to come by on the net, so I will be grateful if someone would elucidate.

Cheers,
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Old 3rd February 2009, 12:13   #51
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Default Please report injector failure experience in common-rail diesels

Quote:
Originally Posted by Ravveendrra View Post
Multijet electronically controls the injectors to spray the fuel in short bursts (5 bursts if I remeber correctly) in each cycle, whereas the others inject the fuel in one shot.
If that be so, it would seem the injectors are operating 5 times in each cycle, instead of once as in CDi. The wear and tear on the injectors should in that case be much higher than in CDi, with a shorter life span. They're expensive (Accent CRDi injectors cost over Rs.30,000 each), and they might fail sooner than anticipated in a CDi/CRDi/DICOR/CRDe engine.

Can members please comment on their experience with injector failure if any, while driving any common-rail / JTD engine? and the costs involved in different makes of cars?

Last edited by SS-Traveller : 3rd February 2009 at 12:15. Reason: Grammar correction
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Old 3rd February 2009, 18:04   #52
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Well all common rails at present are controlled electronically, solonoid or piezo electric for small engines and electro-hydraulically in large engines. The number of injections are varied depending on the way people want the engine to behave. All engines have multiple injections - the number and rate of injection can vary.

It is just a different name given by makers to have unique identity.
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Old 3rd February 2009, 23:40   #53
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Quote:
Originally Posted by Ravveendrra View Post
Yes GTO and SS-traveller, you are right in a way. The MultiJet is a CDI engine but, with a twist in the tail.

The difference between other CDI units and the Multijet (which is owned by Fiat & GM) is that the Multijet electronically controls the injectors to spray the fuel in short bursts (5 bursts if I remeber correctly) in each cycle, whereas the others inject the fuel in one shot. Fiat & GM claim that this means quieter combustion, minimised vibration, reduced emissions, better performance and improved FE.

Fiat and GM call the Multijet engines as JTD, Tata calls it Quadrajet and Suzuki calls it DDIS.

As far as I could make out, the differnce between CDI (CRDI, CRDE etc.) and Multijet is in the number of times the fuel is injected in each cycle of the piston.

Material on this is difficult to come by on the net, so I will be grateful if someone would elucidate.

Cheers,
Yes you are absolutely right Ravveendrra . Guys, What GM or FIAT claims is true. Multijet is nothing but the amount of fuel that needs to be injected per power stroke is split into 4 or 5 split injections. the split is made like this: pre-TDC, TDC and post-TDC. now the pre and post TDC can be further split. the only injection that contributes to the power production is the injection made at TDC. then why do you need pre and post? the common rail engines are always DI and not IDI. how to achieve the IDI behaviour in a DI? the injection which is made before TDC gives you the advantages of prechamber of an IDI. results in noise reduction to greater extent. then why do you need to inject after TDC? have you guys noticed any black smoke coming out of crdi engine? no. its because of the particulte filter used in the exhaust. since this filter gets cogged with the carbon particles which eventually blocks the exhaust, there needs a mechanism to burn the unburnt carbon particles on the filter hence cleaning up the filter. this is done through the injections made after TDC.
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Old 4th February 2009, 10:52   #54
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Quote:
Originally Posted by SS-Traveller View Post
If that be so, it would seem the injectors are operating 5 times in each cycle, instead of once as in CDi.?
Quote:
Originally Posted by star_aqua View Post
What GM or FIAT claims is true. Multijet is nothing but the amount of fuel that needs to be injected per power stroke is split into 4 or 5 split injections.
@ Star_aqua: Thanks for the explanation, it's an eye-opener. You ARE the specialist in this area. Which leads us to my previous question quoted above - what about the increased wear and tear of these injectors? And what is the average life (and cost) of these injectors as per Bosch, both in Multijet and CRDi?
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Old 4th February 2009, 12:11   #55
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Must say this discussion has been very enlightening and interesting as well. At least now some of us know some bits and functions of the engine components that drive us day in and day out, technologies which have become common jargon (in my case used without knowing what it actually is).

This jargon can now be used with a little more confidence.
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Old 4th February 2009, 23:16   #56
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Quote:
Originally Posted by SS-Traveller View Post
@ Star_aqua: Thanks for the explanation, it's an eye-opener. You ARE the specialist in this area. Which leads us to my previous question quoted above - what about the increased wear and tear of these injectors? And what is the average life (and cost) of these injectors as per Bosch, both in Multijet and CRDi?
The injector is the most precision component among any other component in the common rail engine. for an instance, the nozzle has holes of <0.6mm. and the injectors are self lubricated with fuel. there are no much wear and tear involved. it is designed to last longer than the fuel pump. and with the piezzo injector the mechanical movements involved inside the injector is almost NIL compared to the solenoid injectors.
and am not aware of the cost, but definately they are very costly due to the precession involved in it. but not 30k per injector as told by some member here.

Please note CRDi also has multiple injections and does not differ with MultiJet.
Also when there is a need to change the injector, please make sure that A.S.S guy codes the ECU with the New Injector code after replacing. Every injector comes with a code which specifies its tolerence and the energising values which are different for each injector. just simply one cannot change the injector without re programing the codes in the ECU.
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Old 14th May 2009, 14:26   #57
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Default TDI Versus CRDI

Hi Friends

VolkSwagen car still comes with TDI diesel engines.
Except that group, most OEM's producing diesel cars are extensively using CRDI engines.
Can someone throw some light on the underlying technical aspects.
Which one is superior in terms of power, fuel economy, drive behavior and other factors.
Now a days VW car have also started using CRD technology.
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Old 14th May 2009, 17:25   #58
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I believe the TDI engines use Pumpe-Duse tech

which has been discussed in the following thread
http://www.team-bhp.com/forum/techni...nown-crdi.html (Pumpe-Duse diesel technology as against better known CRDi)
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Old 14th May 2009, 17:41   #59
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TDI - Turbocharged Direct Injection
CRDI - Common Rail Direct Injection

I belive it is not necessary for a CRDI to have a Turbo.
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Old 14th May 2009, 17:50   #60
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Quote:
Originally Posted by Mpower View Post
Guys PD(or unit injector) has been in use for many years in heavy European/US trucks. Back in the day before Common rail was invented PD was the only system able to produce super high pressures. Back then there were either IDIs or VW's TDI. Then VW adapted PD with electronics for light duty car diesels with pilot injection, whereas the others went the common rail route. (dont ask why... VW simply likes eccentric engineering) The advantage was that PD was still producing higher pressure at the cost of refinement.

Well PD stagnated and by the time 2nd gen common rail was introduced, they had caught up with injection pressures. Time to bury the PD for high refinement cars but trucks still swear by them.
The PD design was a reaction to the development of common rail fuel injection by competitors - an attempt by Volkswagen Group to create an in-house technology of comparable performance that would not require any royalties to be paid. While Pumpe-Düse engines had a significantly higher injection pressure than older engines, they are not a match with the very latest common rail and weren't able to control injection timing as precisely (a major factor in improving emissions). In Europe new engines appearing in 2009 model year Volkswagens are using the common-rail technique with piezoelectric injectors. I am not sure about engines in VW Indian cars. But they might be going with their PD in India to reduce cost.

Source: Turbocharged Direct Injection - Wikipedia, the free encyclopedia
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