The Technical Truth? :Petrol vs Diesel

[rippergeo]

Originally Posted by reignofchaos

Well the basic flaw in your reasoning is that you are comparing petrols with lame engines to the verna and swift-D. Try driving something that actually has some power.

any suggestions? in similar price ranges and cubic capacities, what cars would you suggest I try?
and I do not think the stock zen or the stock petrol swift have lame engines for city driving.

[BUSA]

ROC - The reason for choosing a Diesel even when cost of fuel is same.

1. Diesel will still give better average. Swift Petrol gives 11, wheras petrol gives 16

2. Diesel Swift is much much more FTD then the Petrol counterpart & so are almost are diesel cars compared to their petrol counter parts(exception being the vRS)

In daily day to day driving, you are using peak torque of the car, wheras how many times do you revv to 4000RPM in regular driving. Petrol cars are said to produce peak torque over 4000RPM Dont get me wrong, i was a total petrol head, till i drove the Verna/Swift If you read my older posts i was highly against diesel vehicles.

I will go for diesel if they keep on producing engines as Hyundai guys have set the trend.

Hyundai makes some fabulous diesel engines. Case in point is the Verna engine, it is a nuke

Well the basic flaw in your reasoning is that you are comparing petrols with lame engines to the verna and swift-D. Try driving something that actually has some power.

There is no point in comaparing a high powered petrol to a diesel which looks underpowered in the comaparission. If the car petrol car is high powered, then it will cost more. Yes, you cant compare the 325i to the 320D but the 325i costs a whopping 4Lacs more. A real comparission will be between a 320i and 320D

The stock Swift petrol engine is fantastic, only thing the diesel overshawdows it.

@ ROC - I would suggest you need to drive a diesel car for long and drive it like a diesel and then you will get the point. Dont revv her, drive in the torque curve.

In that case i would always opt for a super smooth petrol engine.
BUSA Please think beyond TORQUE also...

I agree i am just becoming too muc Torque minded but with the new gen diesels its like having your cake and eating it too, it gives the best of both worlds, and who said diesels dont have good high end, it cant compare to petrol i agree, but its not that bad either.

The turbolag in my terms is not lag but silence before the strom And all Turbo cars will have it whether petrol diesel.

NOTE FROM MODERATOR: Kindly avoid using more than 2 smilies.

[reignofchaos]

Originally Posted by BUSA

2. Diesel Swift is much much more FTD then the Petrol counterpart & so are almost are diesel cars compared to their petrol counter parts(exception being the vRS)

Busa if the diesels were such fun to drive, why is it that still all high performance cars are petrols? The only manufacturer whose diesel engines are superior to petrols in terms of power is Hyundai. Thats because their petrol engines are all just rubbish. Just compare the mercs in terms of power or the BMW 5 series cars.

In daily day to day driving, you are using peak torque of the car, wheras how many times do you revv to 4000RPM in regular driving. Petrol cars are said to produce peak torque over 4000RPM Dont get me wrong, i was a total petrol head, till i drove the Verna/Swift If you read my older posts i was highly against diesel vehicles.

Well in most decent petrol engines, 85-90% of peak torque is available at as low as 2000-2500 rpm. So its not like petrols are torque starved. The diesels on the other hand definitely *ARE* torque and power starved until they turbo kicks in. If you take the turbo off the diesel car, it'll be as slow as a horse carriage. Also diesels typically build revs slower than petrols which only exacerbates the issue.

There is no point in comaparing a high powered petrol to a diesel which looks underpowered in the comaparission. If the car petrol car is high powered, then it will cost more. Yes, you cant compare the 325i to the 320D but the 325i costs a whopping 4Lacs more. A real comparission will be between a 320i and 320D

The stock Swift petrol engine is fantastic, only thing the diesel overshawdows it.

Well the 320d costs 2.5 lacs or so more than the 320i. By your logic, then that isn't a fair comparison either.

The stock swift engine is ancient. Its been doing duty in the esteem for more than 10 years. Frankly to me it feels dreadful to drive as there's no response whatsoever. On the other hand the MJD engine is newer tech and obviously it should perform better. FYI the folks at top gear consider the same diesel engine which also does duty in the Fiat 500 as *absolute rubbish* when they reviewed the Fiat 500. [either S10E8 or E9]

Still still still.... a stock swift petrol is faster than a stock swift diesel . Why you ask me? Just because of the turbo lag.

@ ROC - I would suggest you need to drive a diesel car for long and drive it like a diesel and then you will get the point. Dont revv her, drive in the torque curve.

Trouble is that I find them way too slow when not in the power band if I don't rev them quickly into the power band. Once you are in the powerband, obviously there's no reason to rev the engine.

The turbolag in my terms is not lag but silence before the strom And all Turbo cars will have it whether petrol diesel.

The difference between turbo'ed petrol and diesel cars is that the petrols are still pretty nimble when not in the power band... that is unless you do stupid things like 6th gear at 30mph.

@rippergeo: Drive a palio 1.6 once. Its in the same price bracket as your swift diesel. Once you drive it, you'll know what a real petrol engine is like. Or drive any of the higher end sedans... corolla/civic/cedia/octy tpi. One thing to note is none of them other than the octy petrol will give you a huge boost like the diesels. However without realizing, you'd be doing much faster than what you did in your verna or swift.

[BUSA]

Roc - I agree with you that some petrol engines are fantastic as far as FRD is concerned but in India, almost 90% cars having both versions, the diesel seems a better bet. Maybe since companies dont bring high end petrol versions avoid pricing it on par with the diesel.

The Palio 1.6 is such a fantastic machine, the engine is a gem butttttttt it drinks like no other, on high revving and spirited driving it gives not more then 7kmpl AFAIK.

P.S The car which one the Le Mans was a Audi R10 with a TDi engine.

P.S 2 It was the 9th episode of this series TG. They also admitted that diesel cars have gone quite ahead when they tested the BMW Diesel in a 24 hours endurance race.

[Jeep]

1. Petrol. I love the NVH characteristics of petrol cars. The slightly more efficient diesel engine is not going to change my mind. Added bonus is that Petrol engines are cheaper to maintain and more reliable than diesels any day

2. Petrol again. It will be easier to maintain a petrol car (or are you asking me 'what if diesels were equally easy on maintenance'?)

Originally Posted by BUSA

1. Lets say the cost of one liter of petrol and diesel is the same. Would you still pay the premium on diesel engine cars? Or would you opt for the petrol vesion? Its not the cost of fuel its the fact the diesel cars have better driveability.

2. The price of Petrol and diesel per litre is the same, and the cost of the car is also the same. Then what would be the choice? Diesel, diesel, diesel....... and so on and so forth.

[enzo10]

It is on steep inclines as is the case on ghats or hilly Kerala, were you will admire the petrol engine, it takes ages to climb a steep incline in a diesel engine.

even though the VGT has solved this issue to some extent, a 3 pot alto will glide the ghat when compared to a 4 pot diesel

[reignofchaos]

Originally Posted by BUSA

Roc - I agree with you that some petrol engines are fantastic as far as FRD is concerned but in India, almost 90% cars having both versions, the diesel seems a better bet. Maybe since companies dont bring high end petrol versions avoid pricing it on par with the diesel.

The Palio 1.6 is such a fantastic machine, the engine is a gem butttttttt it drinks like no other, on high revving and spirited driving it gives not more then 7kmpl AFAIK.

Completely agree that good performance petrol engines guzzle. Petrols will never come close to diesels in fuel economy. However IMHO in everything else, they are just way way better.

P.S The car which one the Le Mans was a Audi R10 with a TDi engine.

P.S 2 It was the 9th episode of this series TG. They also admitted that diesel cars have gone quite ahead when they tested the BMW Diesel in a 24 hours endurance race.

If you remember, JC mentioned why the Audi R10 won Le Mans... its cos it made one third the number of fuel stops as compared to the gas engines, not because of the power or anything.

[rippergeo]

Originally Posted by reignofchaos

@rippergeo: Drive a palio 1.6 once. Its in the same price bracket as your swift diesel. Once you drive it, you'll know what a real petrol engine is like. Or drive any of the higher end sedans... corolla/civic/cedia/octy tpi. One thing to note is none of them other than the octy petrol will give you a huge boost like the diesels. However without realizing, you'd be doing much faster than what you did in your verna or swift.

the palio 1.6 has a full 300cc more than the little swift d
I suppose the real comparison would be with a 1.3 litre petrol at that price bracket. even then it is only 3 secs quicker than the swift D

ofcourse in a drag race, the petrols would win, but in the roll on acceleration timings, the diesels would win.

and its not all about revving and top speed. its about flexibility that the diesel power delivery offers.

if you tried to lug a petrol from idle like a diesel, you'd get a same lag kind of feeling

if you floor a diesel while its at idle while you are running at a speed of 10-20kmph nothing is going to happen unless you are in the right gear. same as with petrol.
but the diesel will be pulling well in the 3rd gear while the petrol will have to downshift to the 2nd

[rippergeo]

Originally Posted by enzo10

It is on steep inclines as is the case on ghats or hilly Kerala, were you will admire the petrol engine, it takes ages to climb a steep incline in a diesel engine.

even though the VGT has solved this issue to some extent, a 3 pot alto will glide the ghat when compared to a 4 pot diesel

enzo- i dont get it. you're going down the wrong road, any decent ghat driver will pick a torquier diesel engine like the mahindra or a tata to climb inclines and descend them. torque is essential in the hills. that too, low down torque, which petrols find difficult to make.

in a hilly section,a petrol would have to slip the clutch during standing starts and rely heavily on the brakes during descents to prevent the engine from over revving

any other arguments against the diesel can be understood to some extent. but never the argument that diesels are worse off in the hills(I drive these steep hills of kerala too)

PS- we're talking new gen diesels not the ambys.
even the older gen diesels in mahindras are brilliant on the hills, better than little hatches with rev happy engines.

[DirtyDan]

Originally Posted by rippergeo

enzo- i dont get it. you're going down the wrong road, any decent ghat driver will pick a torquier diesel engine like the mahindra or a tata to climb inclines and descend them. torque is essential in the hills. that too, low down torque, which petrols find difficult to make.

in a hilly section,a petrol would have to slip the clutch during standing starts and rely heavily on the brakes during descents to prevent the engine from over revving

any other arguments against the diesel can be understood to some extent. but never the argument that diesels are worse off in the hills(I drive these steep hills of kerala too)

PS- we're talking new gen diesels not the ambys.


even the older gen diesels in mahindras are brilliant on the hills, better than little hatches with rev happy engines.

We are comparing apples and oranges here. How do you decide what set up in a petrol versus diesel constitutes relative equality and then, having decided that, how do you decide they are not equal and that one is better?

[Magma]

wow
man, i definetely bit off more than i can chew! (thanks busa,jat,ripper ,reignofchaos and all)
this is a full blown crash course on diesel vs petrol!
well now you can understand my confusion about considering a diesl engine though i dont drive much! ( just 50kms weekly only in the city!!)
what do you guys think ? do you guys see Any problem(expensive maintenence etc etc ) for me buying a diesl engine car though i have lower running in the city?

[aravindwarrier]

My replies in bold:

Originally Posted by rippergeo

the palio 1.6 has a full 300cc more than the little swift d
I suppose the real comparison would be with a 1.3 litre petrol at that price bracket.

Is that so? Seems you forgot to count the turbo? The volumetric efficiency of an engine is enhanced by turbo,hence a turbocharged engine can be desingned to be of smaller CC Vis-a- Vis a comparable output NA unit.

and its not all about revving and top speed. its about flexibility that the diesel power delivery offers.

Well priorities do vary, but flexibility is more of a priority in a UV, which will be overloaded more often than not, compared to a performance car, for which the load is more or less pre-defined.

For me, or for that matter most of the people who enjoys driving, will prefer the convenience,power, NVH and easy upkeep of a petrol provided cost is not an issue.

if you tried to lug a petrol from idle like a diesel, you'd get a same lag kind of feeling

The steady diet of economiser petrols which we have seen over the years definitely are underpowered.But A turbodiesel (less pronounced but still noticeable even in the VGT Verna) do have a pronounced lag, before the turbo kicks in.
Underpowered they may be but i am yet to see a NA petrol with a lag and a TD without a lag.

Originally Posted by rippergeo

enzo- i dont get it. you're going down the wrong road, any decent ghat driver will pick a torquier diesel engine like the mahindra or a tata to climb inclines and descend them. torque is essential in the hills. that too, low down torque, which petrols find difficult to make.

in a hilly section,a petrol would have to slip the clutch during standing starts and rely heavily on the brakes during descents to prevent the engine from over revving

any other arguments against the diesel can be understood to some extent. but never the argument that diesels are worse off in the hills(I drive these steep hills of kerala too)

PS- we're talking new gen diesels not the ambys.
even the older gen diesels in mahindras are brilliant on the hills, better than little hatches with rev happy engines.

Well you are correct here, but hey,in the same vein, I feel that While we are talking new gen diesels, we are much much far away from the new gen petrols, obviously because of our fixation on FE. The Toyota/Honda petrol engines (IDSI,VVT), or even for that matter the VTVT verna engine is much smoother than diesels, IMHO.

[kpzen]

Guys.
The thread is about Petrol v/s Diesel and not Swift D v/s others.!!!!

[hrman]

ON the diesel vs Petrol saga, I used to have a Indica DLS..-Non Turbo. I think I realised where all the arguments against diesel came from. It always felt underpowered on slopes and when starting from scratch. When the speed was constant or it had picked up steam, it was good to drive.
I just stumbled upon a petrol Wagon R and Boy oh boy, i loved the feel of the engine splurge when you touched the accelerator.
Then I drove the NHC and loved it and bought it immy.That was 3 months ago. My impression on diesels was till now shattered with the Indica Non-turbo machine. It was more suited for its fuel economy and space. No driving pleasure whatsoever.
I recently stumbled upon the Getz D and the Swift D.. Man, this is what a diesel engine should be like.. It just zoomed over 2 k RPM. You get a great recoil, like hitting your head on the headrest when you accelerate them. Now thats true diesel power and refinement. And great average, much better than the petrol model. If you compare a petrol version of any car with their diesel counterpart, please also look at the Turbo refinement and the Combined rail technology in the diesel sibling. This certainly gives it a hands down victory over the petrol variant in most cases..
Long term maintenance costs of diesel engines may be only marginally higher than the petrol engines. And this is more because of the complexity of the diesel engines than anything else.
I have'nt yet driven the Optra Magnum diesel, but would love to try it. Am sure Ill fall in love with it..

[DirtyDan]

Originally Posted by hrman

Long term maintenance costs of diesel engines may be only marginally higher than the petrol engines. And this is more because of the complexity of the diesel engines than anything else.

Long term costs of diesel maintenance is considerably LOWER than a petrol engine. No tune ups. And, the life of a diesel is often nearly twice that of petrol engines. You will find also that manufactureres generally give a longer warranty for their diesels because of this fact.
Yes, it depends how they are treated and maintained, of course. I am not sure I would buy a second hand Getz, knowing how somebody is likely to have driven the cr*p out of it.

Mr. Jat, I enjoyed reading your posts here. Good stuff.