Go Back   Team-BHP > Under the Hood > Technical Stuff


Reply
 
Thread Tools Search this Thread
Old 29th October 2011, 01:16   #31
BHPian
 
Join Date: Aug 2008
Location: Pune
Posts: 59
Thanked: 8 Times
Default Re: Petrol versus diesel cars - reliability

Quote:
Originally Posted by IndigoXLGrandDi View Post
@thermalpaste..
How to get the Timing Belt adjusted Correctly from a Local Mechanic?
Local Mechanics avoid "Correct Adjustment of Timing Belt" since Incorrect Adjustment leads more revenues to them.

Is it correct that Common Rail Engines don't start if Timing Belt is not PERFECTLY fitted?

If slight variation is present, will it result in rough idle?
Common rail engines use an ECU to govern timing -- there is no injection pump, only a high pressure pump. Which car do you have?
thermalpaste is offline   Reply With Quote
Old 29th October 2011, 09:11   #32
Distinguished - BHPian
 
Sheel's Avatar
 
Join Date: Jul 2006
Location: Purnea(Bihar)
Posts: 5,210
Thanked: 4,846 Times
Default Re: Petrol versus diesel cars - reliability

Quote:
Originally Posted by blackfire_9 View Post
2. Innova -- my office cab, has done about 7.27 lacs till date on stock engine & the reason I had even asked about the mileage was because it didn't feel out of shape despite being a taxi.
A photograph of this would be real nice. I have seen miles logged in an an Accord (US) in photographs of course, 5L miles & counting.
Sheel is offline   Reply With Quote
Old 29th October 2011, 22:03   #33
Senior - BHPian
 
thoma's Avatar
 
Join Date: Oct 2011
Location: Kerala
Posts: 1,750
Thanked: 1,073 Times
Default Re: Petrol versus diesel cars - reliability

I am confused about the reliability of modern diesels for city use with quite a high number of engine start stops? Does frequent engine start stops harm the diesel engine more than a petrol engine?

Moreover, does the same amount of harm (read as - under similar operating conditions) for a petrol and diesel engine lead to higher maintenance cost for the diesel than for the petrol engine car?
thoma is offline   Reply With Quote
Old 30th October 2011, 13:19   #34
BHPian
 
Join Date: Mar 2010
Location: Land of Temples
Posts: 55
Thanked: 7 Times
Default Re: Petrol versus diesel cars - reliability

Quote:
Originally Posted by Anarchy83 View Post
This is quite an interesting thread and I have a couple of points to raise here. Keep in mind, I'm not of the belief that either engine is better or worse - the differences I point out are merely characteristics of the intended usage.

Diesel Engines:

Higher torque at lower RPMs - thus the usage in trucks, tow vehicles etc. However, this also has a negative connotation regarding power - less BHP from a diesel engine as compared to a petrol engine of the same engine capacity.
@Anarchy83: Just thought of bringing this to your attention. The diesel engine of the VW Polo (a 1198 cc, 3-cylinder unit) puts out 75 PS @ 4200 RPM whereas the Petrol motor (1198 cc & 3 cylinders) produces the same output (75 PS) at 5400 RPM. Coming to the torque settings, the Diesel has a torque output of 180 NM @ 2000 RPM and the Petrol engine has a torque of 110 NM @ 3750 RPM (Source: VW India website).
LPT2625 is offline   Reply With Quote
Old 31st October 2011, 20:04   #35
Senior - BHPian
 
IndigoXLGrandDi's Avatar
 
Join Date: Aug 2009
Location: Solapur (MH-13)
Posts: 1,029
Thanked: 160 Times
Default Re: Petrol versus diesel cars - reliability

Quote:
Originally Posted by thermalpaste
Common rail engines use an ECU to govern timing -- there is no injection pump, only a high pressure pump. Which car do you have?
Tata Indigo XL Grand Dicor which has run 1,41,000kms.
IndigoXLGrandDi is online now   Reply With Quote
Old 1st November 2011, 00:54   #36
BHPian
 
Anarchy83's Avatar
 
Join Date: Sep 2011
Location: Bangalore
Posts: 63
Thanked: 44 Times
Default Re: Petrol versus diesel cars - reliability

Quote:
Originally Posted by LPT2625 View Post
@Anarchy83: Just thought of bringing this to your attention. The diesel engine of the VW Polo (a 1198 cc, 3-cylinder unit) puts out 75 PS @ 4200 RPM whereas the Petrol motor (1198 cc & 3 cylinders) produces the same output (75 PS) at 5400 RPM. Coming to the torque settings, the Diesel has a torque output of 180 NM @ 2000 RPM and the Petrol engine has a torque of 110 NM @ 3750 RPM (Source: VW India website).
Thanks for bringing that up LPT2625. When we compare the output of an engine, I would tend to think up and down the entire range across all gears - else, for example, we might confuse characteristics like short gear ratios to mean stellar power.

Personally, I drive a diesel. Having said that, when I mentioned less BHP from a similar engine, I mean't to say that diesel engines do not tend to be very effective all the way to near red-line. Petrol engines are far more so.

Fundamental reason - diesel engines have comparatively longer compression and ignition cycles (in terms of crankshaft diameter) as compared to a petrol engine. This means in a single ignition stroke, a diesel engine can produce sustained torque but relatively far less power than a petrol engine. This is also the reason why diesel engines are expected to have more torque than petrol.

In a nutshell, torque produced by an engine works on three components - amount of pressure exerted by the ignited fuel on the piston face, the surface area of the piston face and the diameter of the crankshaft. All three would typically be larger in diesel engines (by virtue of it being a compression ignition system).

I had got an equation about the relationship between Horsepower and Torque at Power and Torque: Understanding the Relationship Between the Two, by EPI Inc. . It goes as below

"Horsepower = Torque x (RPM/5252)"

In essence, without seeing any increase in torque, we can see an increase in horsepower on the basis of increase in RPM. This is where diesel engines fall behind petrol engines - a diesel engine with equivalent torque as a petrol engine is not capable of sustained high RPM (as in the case of petrol engines), and therefore does not deliver higher horsepower across all gears.

If two engines can produce the same torque, whichever one can output that same amount of torque more times in a shorter time period would produce more horsepower. Keeping this in mind, 10 times out of 10, a petrol engine would be better than a diesel engine. I'm confident about petrol outwitting us diesel behemoths is cause of the shorter cycles across all strokes.

Of course, most of this is based on my theoretical knowledge only. I would be interested to know if the basis of this knowledge is wrong in any way.
Anarchy83 is offline   (3) Thanks Reply With Quote
Old 1st November 2011, 01:00   #37
BHPian
 
Anarchy83's Avatar
 
Join Date: Sep 2011
Location: Bangalore
Posts: 63
Thanked: 44 Times
Default Re: Petrol versus diesel cars - reliability

Quote:
Originally Posted by thoma View Post
I am confused about the reliability of modern diesels for city use with quite a high number of engine start stops? Does frequent engine start stops harm the diesel engine more than a petrol engine?

Moreover, does the same amount of harm (read as - under similar operating conditions) for a petrol and diesel engine lead to higher maintenance cost for the diesel than for the petrol engine car?
I would like to think not Thoma. Diesel, as a fuel is far less corrosive than petrol. Also consider that the efficiency of a petrol engine is approx. 35% in terms of fuel burnt. Compare this with a near 48% efficiency in most diesel variants. I think in terms of coping with frequent stop/starts, diesel would be just fine.

Again, do correct me if I'm going wrong somewhere.
Anarchy83 is offline   Reply With Quote
Old 1st November 2011, 08:15   #38
BHPian
 
Join Date: Mar 2010
Location: Land of Temples
Posts: 55
Thanked: 7 Times
Default Re: Petrol versus diesel cars - reliability

@Anarchy83: Thank you for your reply. You are definitely more knowledgeable on the subject than me. At the risk of not bombarding you with too much information, here is something I think you might find enlightening, under the section 'The Driving Force'.

Last edited by LPT2625 : 1st November 2011 at 08:17. Reason: Supplementary information
LPT2625 is offline   Reply With Quote
Old 1st November 2011, 13:07   #39
BHPian
 
Anarchy83's Avatar
 
Join Date: Sep 2011
Location: Bangalore
Posts: 63
Thanked: 44 Times
Default Re: Petrol versus diesel cars - reliability

Quote:
Originally Posted by LPT2625 View Post
@Anarchy83: Thank you for your reply. You are definitely more knowledgeable on the subject than me. At the risk of not bombarding you with too much information, here is something I think you might find enlightening, under the section 'The Driving Force'.
Leave it to Audi to create art eh? Consider that they claim there is no obstruction to the air outflow.

Noise is unused energy," stresses Dr. Wolfgang Ullrich who is delighted by the whispering murmur of the R18 TDI.

Brilliant!!! In a day and age when noise is equated to engine muscle, it is refreshing to hear the voice of reason.

On another note, we have to keep in mind that the engine used is ages ahead of the diesel engines we have in our standard-issue on-road steeds.
Anarchy83 is offline   Reply With Quote
Old 1st November 2011, 13:35   #40
Distinguished - BHPian
 
dhanushs's Avatar
 
Join Date: Oct 2009
Location: Bathery/BLR
Posts: 3,446
Thanked: 4,057 Times
Default Re: Petrol versus diesel cars - reliability

Quote:
Originally Posted by thermalpaste View Post
Common rail engines use an ECU to govern timing
Fuel Injection timing or valve timing?
dhanushs is offline   Reply With Quote
Old 1st November 2011, 15:19   #41
RGK
Senior - BHPian
 
RGK's Avatar
 
Join Date: Feb 2010
Location: DPM and CHN
Posts: 1,355
Thanked: 206 Times
Default Re: Petrol versus diesel cars - reliability

Quote:
Originally Posted by dhanushs View Post
Fuel Injection timing or valve timing?
I think ECU governs Fuel Injection & Pump timing. Valve timing is managed mechanically by Cam shafts.

Quote:
Originally Posted by Sheel View Post
A photograph of this would be real nice. I have seen miles logged in an an Accord (US) in photographs of course, 5L miles & counting.
Quote:
Originally Posted by blackfire_9 View Post
2. Innova -- my office cab, has done about 7.27 lacs till date on stock engine & the reason I had even asked about the mileage was because it didn't feel out of shape despite being a taxi.
Absolutely. Diesel engines have logged lacs of KMs. My friends Amby with fitted Izusu (D series) engine has run 6.5 lac km without any major problem and still running.
Japan diesels like Mitsubishi, Toyota have clocked 3 Lacs and more.
Coimbatore Auto Garage deploy imported (used engines) diesels for all modern cars like Accent and they clock huge kms. European diesels dont lag far behind.

For peppy driving & zero engine noise - go for petrol else diesel. In India, petrol cars are not driven for longer miles even though they are capable of.

OT: In late 80s' new Ambassador's were fitted with Matador 305 diesel engines. The new sealed engine from bajaj came around 40,000/- whereas the petrol engine inside the Ambassador was sold for meagre 1,500/- .
RGK is offline   Reply With Quote
Old 2nd November 2011, 21:19   #42
Senior - BHPian
 
Ricky_63's Avatar
 
Join Date: Dec 2006
Location: Gurgaon
Posts: 3,847
Thanked: 377 Times
Default Re: Petrol versus diesel cars - reliability

Quote:
Originally Posted by thermalpaste View Post
IMO, the Lancer diesel is the most reliable diesel. I have clocked 3,50,000 on mine and the only parts I have replaced are the water pump and the timing belt.
Quote:
Originally Posted by thermalpaste View Post
Common rail engines use an ECU to govern timing -- there is no injection pump, only a high pressure pump. Which car do you have?


W O W 3.5L on the odo is quite something, though I have sat in a deisel Lancer, it felt nice..but never knew it was capable as that Kudos to the maintainence..

Does the Lancer D not have a injection pump ? Just curious.

By that same yardstick I feel the Pajero is a workhorse like no other.




Cheers
Ricky_63 is offline   Reply With Quote
Old 18th November 2011, 17:57   #43
BHPian
 
ankurvirmani19's Avatar
 
Join Date: Sep 2011
Location: Faridabad
Posts: 249
Thanked: 76 Times
Default Re: Petrol versus diesel cars - reliability

Got an article differentiating Petrol vs Diesel Economies of Scale

Source: Zigwheels

With the prices of petrol skyrocketing, car buyers seem to be lining up to book diesel variants as they are highly economical and easy on the pocket compared to their gasoline counterparts. Well, that is only if you discount everything else and consider the running cost. We at ZigWheels take a look at the bigger picture and bring it down to simple numbers to find the cost-effective option between petrol and diesel fueled variant

The acceptance of diesel vehicles has witnessed a rapid rise in the last decade in India. With the advent of new technologies such as common rail direct injection, EGR systems and exhaust treatment systems, diesels today offer great performance, excellent mileage and on many accounts it is the cleaner fuel! The inherent ability of diesel engines to produce excellent low end torque makes for great driving; however these factors basically aided diesel engines to gain an acceptance in the passenger car market as they didn't spew black smoke like in the past. The icing on the cake however has to do with the pricing of fuel. Assuming Diesel is priced at around Rs. 50/litre and petrol is approximately Rs. 70/litre. The rates change in different parts of the country; however the ratio of difference between the two is more or less the same. It is the cumulative knowledge of all these facts that make diesel engined passenger vehicles the number one choice for many customers, however there is a kink in the diesel armour and that has to do with the pricing of the vehicle as compared to its petrol counterpart.

A deeper insight is required while trying to decipher the cost benefit between diesel and petrol vehicle variants. Elements such as the timeline of usage, cost difference between the two models, fuel price disparity, maintenance expenses and service charges, parts wear and tear and depreciation costs sum up the major list to assist in calculating the actual benefit. It is a line of thought that most customers overlook, however our cost-benefit study should shed some light on the topic and hopefully help customers make a more informed decision, rather than just going with gut instinct or following the claims of manufacturers.


Note: The study is based under the following assumptions:
• Costs of Petrol and diesel are for representational purposes only
• The difference in price of petrol and diesel remains constant throughout the five years.
• Cost of repairs and maintenance on both the variants remains nil or equal.
• Both the variants will bring in 50% of the cost at the time of resale
• Average driving is 15,000kms/year for both the variants. (in case 2)
• The car model under consideration is the new Maruti Suzuki Swift (entry level variants for both diesel and petrol). This is only indicative, and gives a good idea since the difference of cost between petrol and diesel variants of other cars also hovers around the same figure.


We did the math to compare the cost of operation for an entry level Maruti Suzuki Swift petrol with the diesel variant. The difference in the cost of the two variants is Rs. 90,000 with diesel being the more expensive of the two; add to that the interest one would gain on the excess amount at 10% p.a if the petrol variant was purchased. The diesel variant being more efficient and the cost of diesel being Rs. 20/litre lesser than that of petrol, it saves a lot of expenses on fuel (See Case 1), but the cost of regular maintenance of the diesel variant is higher than that of its petrol equivalent. Taking all these dynamics into account, the running cost of a petrol car comes to approximately Rs. 4.93/km in comparison to Rs. 9.5/km for the diesel if both the vehicles are run for 15000kms annually. Increasing the annual mileage put on the odometer, the diesel is at par with the petrol variant if and only if a person does a minimum of 45,000kms annually.
Low running? Wait for longer to recover costs

Now, it is understandable that an average Indian cannot put 45,000kms on the odometer annually considering the average run of an Indian being around 15,000kms per year. So does that totally rule out the diesel option? Well, no. Reverse calculating the amount of money saved on fuel (See: Case 2) by using a diesel car amounts to Rs. 30,500 annually after deduction of service costs for both the vehicles. Even so, after adding interest on the additional amount paid by a buyer at the time of purchase the diesel would be at par with the petrol variant mid-way through the third year. At the end of the fourth year with an annual running of 15,000kms, the money you would have saved in terms of running costs in a diesel would cover up the extra price you have paid, and you would have saved an extra Rs 9,700 as well. Only at the end of the fifth year do things begin to look rosy for diesels, with around Rs 40,000 saved in running costs over these five years.

What about depreciation?
Alright, so you finally made up the extra amount you spent in the initial invest of a diesel car, but what about depreciation? Assuming that both the variants have been reduced to half their cost after 5 years, you will still be losing more money in depreciation for the diesel, since it was a more expensive buy to start with.

The value of a Rs 4.95 lakh petrol car will be reduced by Rs 2.47 lakh at the end of five years. The value of a Rs 5.85 lakh diesel car on the other hand will be reduced by Rs 2.92 lakh – that’s Rs 45,000 lost straight in depreciation for a diesel.

This is an extreme scenario, we accept. The market dynamics for more-in-demand second hand diesel car space may result in lesser depreciation, and a better resale price. Either ways, the Rs 40,000 that a diesel user may gain after using the car for five years starts looking less rosy once you factor in depreciation as well.

Although, with the price of petrol is as high as Rs. 70/litre, the diesel may seem like a more affordable option, it may not necessarily be so. The diesel starts making economic sense for users who either have a run of 45,000kms annually or those who plan to retain the car for atleast five years or till the time they hit 50,000 kms on the odometer. And for those who have much less travelling to do in a car, the petrol still makes for a better buy.

What about the feel factor?
Although mathematics seem to be in favour of a petrol car unless you plan to retain a diesel for a prolonged period or drive seriously long distances within the first year itself, it is clear that the choice between petrols and diesels also has other angles that must be considered before making that final call.

Psychological satisfaction is of utmost importance to an Indian customer; and along with it comes the mental peace of not having to refuel a diesel car every few days unlike the petrol equal which is pretty much perpetually thirsty. But, simply the fact that the diesel needn’t be refueled very frequently doesn’t make it a more economical option. A diesel starts making sense only when you have a run of at least 15,000kms anything less than that and diesel will smartly fool you into feeling richer just because you end up filling fuel less frequently.

It is not just the thirst for fuel of petrol cars that brings diesel vehicles into the lime light. The numbers before you clearly state, that you should consider buying a diesel only if your monthly run exceeds a 1000 kilometres. In fact our thesis was endorsed by Toyota at the recent launch of the Etios and Liva diesels, where they made it very clear that for a diesel to start looking rosy; one has to run it for nearly 2000kms a month. The numbers are before you, so remember that with a diesel, you would still be paying that extra cash for the first three-four years of running for the satisfaction of driving a diesel. It still is a case of different strokes for different folks, and choice still remains in the hands of the buyer. Hope this article helps you make a more informed one.
Attached Images
     
ankurvirmani19 is offline   (1) Thanks Reply With Quote
Old 18th November 2011, 18:11   #44
BHPian
 
mempheS.D's Avatar
 
Join Date: Dec 2009
Location: Denver, CO
Posts: 536
Thanked: 209 Times
Default Re: Petrol versus diesel cars - reliability

Wonderfully explained! This is definitely some thought process every buyer must go throught before taking a final call.
mempheS.D is offline   Reply With Quote
Old 18th November 2011, 18:50   #45
BHPian
 
Join Date: Sep 2009
Location: Mumbai
Posts: 541
Thanked: 13 Times
Default Re: Petrol versus diesel cars - reliability

The resale of a diesel would be much more in this age as compared to an equivalent petrol.

The assumption stated in the article is wrong in the first place making the whole premise and conclusion not entirely accurate.
jigbarai is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Petrol versus Diesel Cars jessie007 The Indian Car Scene 432 18th December 2017 14:35
Key decision points for Audi A4 versus Mercedes C220 versus BMW 320D ashishkashyap Luxury, Imports & Niche 40 30th April 2017 19:35
Petrol Versus Diesel: Toyota Corolla Altis druberoi Sedans 26 14th December 2010 08:56
Calculated:Diesel versus Petrol. Baleno /NHC/ Accent Crdi Buffetfan Sedans 23 19th September 2005 18:20


All times are GMT +5.5. The time now is 14:44.

Copyright ©2000 - 2017, Team-BHP.com
Proudly powered by E2E Networks