[a4anurag]

Originally Posted by KkVaidya

You said the ECU cuts off fuel !! But then how would the engine idle without the fuel cut off at injectors?

ECU cuts-off fuel supply when the car is in-gear but NO accelerator input. ONLY at this time fuel is cut off.

The engine will idle but coast when the gear is shifted to Neutral.

Anurag.

[ramzsys]

http://www.team-bhp.com/forum/techni...57000-kms.html

With respect to the above thread, (apart from manufacturing defects), what causes a premature timing belt/chain failure?

Every manufacturer will do the long term tests and suggest replacement intervals based on that; but what causes/inputs from the user end causes a timing belt/chain to fail prematurely?

...

From my basic understanding, i suggest that waiting for the engine parts to warm up- (this includes the belts and chains) and avoiding unduly harsh acceleration can help.

[Jeroen]

Originally Posted by ramzsys

http://www.team-bhp.com/forum/techni...57000-kms.html

With respect to the above thread, (apart from manufacturing defects), what causes a premature timing belt/chain failure?

Every manufacturer will do the long term tests and suggest replacement intervals based on that; but what causes/inputs from the user end causes a timing belt/chain to fail prematurely?

From my basic understanding, i suggest that waiting for the engine parts to warm up- (this includes the belts and chains) and avoiding unduly harsh acceleration can help.

On the timing belt/ chain failure: nothing really. Its unusual for it to fail unless there is some defect. Certain engines have been known to have certain problem with for instance tensioners. But otherwise there is very little that goes wrong and if you stick to the manufacturer recommendations you would be fine. Other than manufacturing defects I would say a concern could be how to actually replace them. It does take some knowledge and depending on the engine, some specials tools to replace the chain/belt. Although I don't have data as such, I would think more problems occur after chain/belt replacements as part of normal preventive maintenance then when an engine coming fresh out of the factory. Wont happen immediately, but if not installed correctly with the proper tools, proper tensioning etc, it is a disaster waiting to happen.

There is a huge misunderstanding on this forum what causes wear and tear on an engine. RPM and loading isn't really one of those. It will affect FE but not much else. As a rule of thumb city driving versus highway driving is a much more important factor. The number of cold starts or relatively short drives as well. You drive your car twice a day in the city on the commuter run for thirty minutes, in heavy dense traffic will put a lot more wear and tear on it then the guy who does four hours per day on the highways, running at 2500-3500rpm for hours on end.

Car engines are designed to work across the whole range of rpm and loading. Low revs are often a problem for piston ring cylinder lubrication. Keeping engines revs up tends to be better on engines for lubrication, heat dissipation and stress on the engine and drive train, but of course it tend to comes at the expense of FE. Most engines, diesel as well as petrol, run best from a wear and tear perspective if you run them between 75-100% max loading. That is not typically your best FE, but its best for wear and tear. I wouldn't think much of buying a car that has clocked up 100.000 km in 2/3 years. Because in Europe that means mostly highway miles, high speeds, high rpm. Engine will be barely run in. I have never ever bought a car in my life with less than 100.000 km on the clock (other than my company cars which were always new). But I have had never had any major problems because of wear and tear, or an chain/belt failure.

As long as you don't red line your engine, you will be good. My observation of two years in India is that all drivers seem to be obsessed with low revs. I don't know if that is to get the best FE or what. Even in situations where you really need to accelerate fast I see everybody upshifting very quickly rather then to use the rev band a little bit more liberally.

Ensuring your engine is properly warmed up before giving it the beans is really relevant. Don't look at your cooling water temperature for that. If you have an oil pressure gauge, that is the best indication. Once the oil pressure drops to normal values you will be fine. If you have only an cooling water temperature, wait until it registers normal temperature and add another 5-7 minutes for good measure. It will take that long for the oil and the various engine and transmission components to warm up properly.

Especially modern diesel are hugely efficient, which also means they take a long time to heat up properly. When cold, around or below zero it might take a real long time. Never start your cold engine and leave it idling for minutes to warm it up. This is a particularly bad practice that does cause real wear and tear very quickly, notably on the cylinder liners and piston rings. Its also really bad for the environment if you care for that. Start and drive away immediately but be gentle with the right foot until the engine is properly warmed up through and through.

Jeroen

Jeroen

Jeroen

[SS-Traveller]

Originally Posted by CoolCarNi

While approaching a signal or a traffic snarl, instead of downshifting gears I just bring it to neutral position, take my leg off the accelerator, slow down and then brake to come to a standstill. Am I doing right?

Originally Posted by a4anurag

Simple answer: No!
What you are doing is putting both your car and yourself in risk. What you are doing I'd called 'Coasting'
...DO NOT shift to Neutral and glide. It is ultra dangerous...

My take on this is a little different. If you want to shift to neutral and coast to a stop on the plains, I don't see any reason why not - as long as the speed remains low when you shift to neutral (perhaps 20-25 kmph). At such speeds it really does not make any difference to safety. Try driving an automatic transmission in D, and you'll soon realize that you are anyway on neutral and coasting when you take your foot off the accelerator - there is no engine braking!

Originally Posted by ramzsys

http://www.team-bhp.com/forum/techni...57000-kms.html
With respect to the above thread, (apart from manufacturing defects), what causes a premature timing belt/chain failure?

As Jeroen said, there really is no causal effect of your driving that would lead to timing belt/chain failure. However, one noticeable fault that would most likely have led to the chain failing is low engine oil level - 1.1L as you mentioned in the other thread. Whether the engine lost oil during the drive, or whether the oil was not properly filled at the previous service, would be hard to tell - I presume you did not personally check oil level before setting off. In any case, you are covered under warranty and maintained recommended service intervals, and I don't see why Fiat India would want you to pay for the engine repair. Also, the timing chain did not break, so the engine damage is certainly not related to that.

[condor]

Originally Posted by SS-Traveller

Try driving an automatic transmission in D, and you'll soon realize that you are anyway on neutral and coasting when you take your foot off the accelerator - there is no engine braking!

That is a "special case" scenario, because with AT, the car will respond automatically to either acceleration or braking - without any additional inputs. But in a MT, you are stuck in neutral if you want to accelerate and can, in situations, lose a precious second or two.

[SS-Traveller]

Originally Posted by condor

That is a "special case" scenario, because with AT, the car will respond automatically to either acceleration or braking - without any additional inputs. But in a MT, you are stuck in neutral if you want to accelerate and can, in situations, lose a precious second or two.

We are looking at a situation where the road ahead is blocked, and the option of accelerating does not exist at all - CoolCarNi was specific about the situation being 100-200 metres before a red signal or a traffic holdup.

[KkVaidya]

Originally Posted by a4anurag

ECU cuts-off fuel supply when the car is in-gear but NO accelerator input. ONLY at this time fuel is cut off.

The engine will idle but coast when the gear is shifted to Neutral.

Anurag.

I am still not clear! If the fuel supply is cut OFF, the engine cannot even idle.
Without the injector/carburetor squirting fuel, there is nothing to ignite in the cylinder and thus no force to move the pistons!!

[VSRK]

Originally Posted by CoolCarNi

Thanks Anurag,
But I do this may be for 100 or 200 m and may be a few seconds... My concern was regarding what is the difference between downshifting and neutralising, if I may say so? Also, didn't get your second point.

Good or bad depends on what speed you are shifting to neutral. If it is less than 20Km/hr, then no harm to brakepad. However if speed>40, brake pad has to work a lot to bring to zero speed. I used to shift to neutral when there B2B jam in down slope...just to avoid clutch wear and tear.

[IndigoXLGrandDi]

What is the maximum Rpm in the highest gear at which the wear and tear of Engine is minimum? How long (time and distance) can the car be run at that rpm continuously to avoid damage to engine components?
I am asking in case of Diesel Engine?

Is it <=2000, 2500, 3000, 3500, or 4000 rpm?

[condor]

Diesel's are low-revving. Your optimal rpm would be 2000 rpm - give or take a bit, depending on the engine & drive conditions.

[a4anurag]

Originally Posted by IndigoXLGrandDi

What is the maximum Rpm in the highest gear at which the wear and tear of Engine is minimum? How long (time and distance) can the car be run at that rpm continuously to avoid damage to engine components?
I am asking in case of Diesel Engine?

Is it <=2000, 2500, 3000, 3500, or 4000 rpm?

In case of DDiS, I feel it is best in between 2000 - 2500RPM @ 5th gear. Ride, FE, NVH are ideal at these RPM.

Speeds will be around 80 to 110 kmph.

[SS-Traveller]

Originally Posted by IndigoXLGrandDi

What is the maximum Rpm in the highest gear at which the wear and tear of Engine is minimum? How long (time and distance) can the car be run at that rpm continuously to avoid damage to engine components?
I am asking in case of Diesel Engine?

Is it <=2000, 2500, 3000, 3500, or 4000 rpm?

The answer is already there, irrespective of petrol or diesel engines.

Originally Posted by SS-Traveller

On a long drive (or even otherwise), avoid taking your engine to the redline for more than a few seconds. Keep it to 60-70% of its max rpm and you won't regret it. With a cold engine, keep it to less than 50% of the max revs your car can do.

At, say, 60% of an engine's rated redline RPM, you could operate most modern engines almost indefinitely - until you or the car run out of fuel.

[Jeevith]

So while driving around Bangalore traffic and over the course of many a trip to Coorg, my dad and I have always had these discussions / debate over breaking styles.

For example, either while approaching a signal at a distance or a speed breaker on the highway; my dad believes the more effective (in his words "cost effective") way of breaking or slowing down is to engage the car in neutral (or hit the clutch) and then apply the brakes till the point where you want the car to stop. Having been tough driving by him, I took engage in this style of driving.

However, most of my friends believe that the exact same scenario should be dealt with by not disengaging the gears, but instead down shifting the gears to slow down. I.e. a combination of breaks and gear box.

I still haven't been completely convinced by either my father or my friends as both make fairly sound arguments (or at least they appear so to someone like me).

Dad's arguments go that while it's true the break pads might wear out faster in the long run, the cost of the same does not outweigh the penies saved on account of better mileage (achieved by engaging the car in neutral). He also believes that the alternative way does in fact strain the gear box and engine, cause well technically its lugging.

Friends (and by friends, I mean peers, (fyi I'm 26 years old)) believe that their way of slowing involves better control of the car.

I'm inclined to side with my dad here, cause with things ABS how much of lack of control actually exits by virtue of disengaging the engine!?

Would love to hear more experienced views on this

[phamilyman]

Originally Posted by Jeevith

So while driving around Bangalore traffic and over the course of many a trip to Coorg, my dad and I have always had these discussions / debate over breaking styles.

For example, either while approaching a signal at a distance or a speed breaker on the highway; my dad believes the more effective (in his words "cost effective") way of breaking or slowing down is to engage the car in neutral (or hit the clutch) and then apply the brakes till the point where you want the car to stop. Having been tough driving by him, I took engage in this style of driving.

However, most of my friends believe that the exact same scenario should be dealt with by not disengaging the gears, but instead down shifting the gears to slow down. I.e. a combination of breaks and gear box.

I still haven't been completely convinced by either my father or my friends as both make fairly sound arguments (or at least they appear so to someone like me).

Dad's arguments go that while it's true the break pads might wear out faster in the long run, the cost of the same does not outweigh the penies saved on account of better mileage (achieved by engaging the car in neutral). He also believes that the alternative way does in fact strain the gear box and engine, cause well technically its lugging.

Friends (and by friends, I mean peers, (fyi I'm 26 years old)) believe that their way of slowing involves better control of the car.

I'm inclined to side with my dad here, cause with things ABS how much of lack of control actually exits by virtue of disengaging the engine!?

Would love to hear more experienced views on this

ROTFL. You stirred an ancient hornet's nest - now you must be given a Sisyphean punishment for all your days.

Jokes apart, its been done to death multiple times. Read onwards from:
http://www.team-bhp.com/forum/techni...ml#post2540952

My Summary - do what your heart allows. Both styles work as well if you brake in time.
Commonly recommended best practice - what your friends say.

[shashanka]

Originally Posted by IndigoXLGrandDi

What is the maximum Rpm in the highest gear at which the wear and tear of Engine is minimum? How long (time and distance) can the car be run at that rpm continuously to avoid damage to engine components?
I am asking in case of Diesel Engine?
Is it <=2000, 2500, 3000, 3500, or 4000 rpm?

As I'm sure you already know, IXLGrDi, the diesel engine, because of its inherent combustion characteristics (flame front speed, detonation characteristics, cetane rating limitations etc) runs at considerably lower revs than the comparable gasoline engine, which has revs up to 12-15 K's in the case of racing engines.
Even the current state of the art CRD engines with piezo-controlled injection have this diesel cycle limitation. The diesel engine produces its max. torque at a lower rpm and also maintains this (the so-called flat torque curve) over a - relatively - longer rev range.
So, if you drive, keeping the engine rev range within this torque flat, you are likely to get the best out of the engine, while ensuring its longevity too.