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Old 26th August 2011, 15:44   #91
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Default Re: Does Revving the Engine consistently damage the engine on a longer run ?

IMO occasionally revving ANY engine, irrespective of petrol or diesel, to the redline for a few seconds is not in any way detrimental to the life of the engine. In fact, revving up occasionally in a diesel clears up the soot from the exhaust system, which otherwise builds up during low-rev driving. That said, running ANY engine continuously at the redline is certainly going to reduce its service life.
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Old 26th August 2011, 16:20   #92
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Default Re: Does Revving the Engine consistently damage the engine on a longer run ?

I beg to disagree with anyone here who says you can get the best acceleration by revving a diesel engine to 4 k + rpm's. If you rev till 4 k in 2nd gear, 3rd gear and 4th gear after the engine is out of the peak torque in case of the I20 must be around 3200 to 3400 you are just hitting a wall and slowing a progress without achieving much out of it.

For best acceleration its imperative to shift near the end of the torque band so that when you shift to a higher gear you are again in the meat of the torque band to make the most of the 21 kgm that the I20 produces.

For example if I revved my Swift diesel till 4 k in every gear, sure i ll be doing around 70 in 2nd and 100+ in 3rd but i ll be slower than what I could have achieved if I had shifted from 2nd to 3rd at around 55 and 3rd to 4th at around 85 and so on.
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Old 26th August 2011, 16:36   #93
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Default Re: Does Revving the Engine consistently damage the engine on a longer run ?

My average shift rpm is between 2.8 - 3k rpm. I do go upto 3.5 and 4k many times though (Like when i want to get away faster of the line from a signal or while overtaking on a highway). But its still pretty high compared to what other people shift at.

Quote:
Originally Posted by sagarpadaki View Post
THUMB RULE- Never redline a diesel engine.Its harmful to it in long run.
Morover there is not point in revving i20 diesel upto 3.5K or 4K.Because the max torque is between 1750-2800 RPM.So anything above that will just strain the engine and you wont get any more power out of it since its already out of the power band.
Yeah. I am out of the Torque band. But i still feel the car pulling faster than what it would if i would have shifted it to a lower gear.

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Originally Posted by download2live View Post
You should have taken Ford Fiesta Petrol 1.6.
As others have said. Do not redline the diesel engine if you want to make it last real long.
How i wish My running demanded a diesel and this is the best diesel engine that i could find this side of 9 lakhs.

Quote:
Originally Posted by akshay1234 View Post
There should not be any issues if you continue driving the way you do. All I can recommend is that you maintain the car well and keep the service intervals regular. if you do drive like this all the time, then shifting to synthetic oil is a good idea, try Mobil 1 Delvac 1, and change it about every 8 months. If you continue to use mineral oil then change every 4.5-5k kms. As long as you maintain the engine well high revving it will not cause any issues.
I will surely switch to Synthetic oil when i go for next service then. 8 months, but how many km's do i have to change the Synthetic oil at ? (or is it 8 months / unlimited kilometers)

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Originally Posted by .anshuman View Post
Petrol or Diesel revving an engine hard constantly does increase the rate of wear and tear, except this there is no harm i see in revving an engine. i20's CRDi loves to be revved enjoy it, however the sweet spot for most Diesels is between 2-3k RPM where they make most torque.
I am worried about the wear and tear part. If it can last me 1 lakh km's with this kind of driving, that should suffice. And is the wear and tear you are talking about replaceable/ repairable even if it happens after a lot of running ?

Quote:
Originally Posted by ghostrider View Post
Sorry, wrong. You're confusing torque and BHP. The OP clearly gets his jollies from going as fast as he can do, and shifting at 3.5k or 4k is going to provide MUCH more acceleration than shifting at the revs you've mentioned. Just because an engine provides it's maximum torque within a particular rev-band, that doesnt mean there isn't more power to be had above that band.
Yeah. You are right. It does keep on accelerating even beyond 2750 rpm (The upper limit for the torque band).
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Old 26th August 2011, 16:40   #94
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Default Re: Does Revving the Engine consistently damage the engine on a longer run ?

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Originally Posted by dhanushs View Post
Well, in the OP's case, there is no harm. But, if you consider wear and tear at similar redline for a diesel and a similar capacity petrol, IMO, the diesel will have more wear and tear. Reasons being: Heavier crankshaft, pistons and rods. Infact, I guess these are which prevent the diesel to revv high in the 1st place.
I agree. Since there is a lot of compression needed the parts are heavy and so at higher rpms the torque losses are also higher. Also a longer stroke (than gasoline engine) prevents the diesel engine being more rev happy. Long stroke mean more distance between TDC and BDC and so there is a certain distance to be covered for every stroke. As revs increases diesel engine just cannot cope because time is just not there for all the stroked. Even the fuel pump has limitation if I am not wrong.

Oh and the torque losses at higher revs. I think this adds to the wear and tear at these rpms.
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Old 26th August 2011, 16:41   #95
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Default Re: Does Revving the Engine consistently damage the engine on a longer run ?

Quote:
Originally Posted by Kimified View Post



I will surely switch to Synthetic oil when i go for next service then. 8 months, but how many km's do i have to change the Synthetic oil at ? (or is it 8 months / unlimited kilometers)
Generally a good number to replace synthetic would be 10k kms, but since you say you redline a lot I think 8-8.5k kms would be good. That is if your driving style is such a way that you redline it at least once or twice every time you drive (I do that). If its not then once a year or 10k kms is good.
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Old 26th August 2011, 16:54   #96
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Default Re: Does Revving the Engine consistently damage the engine on a longer run ?

Quote:
Originally Posted by akshay1234 View Post
Generally a good number to replace synthetic would be 10k kms, but since you say you redline a lot I think 8-8.5k kms would be good. That is if your driving style is such a way that you redline it at least once or twice every time you drive (I do that). If its not then once a year or 10k kms is good.
IF the best time to change synthetic oil is every 10K why is it that the manufacturers like Fiat ask us to come back in 15k kms only ?

Also, Does redlining damage the viscous properties of the engine oil ?
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Old 26th August 2011, 17:01   #97
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Default Re: Does Revving the Engine consistently damage the engine on a longer run ?

Quote:
Originally Posted by figo_mba View Post
...at higher rpms the torque losses are also higher. Also a longer stroke (than gasoline engine) prevents the diesel engine being more rev happy. Long stroke mean more distance between TDC and BDC and so there is a certain distance to be covered for every stroke. As revs increases diesel engine just cannot cope because time is just not there for all the stroked. Even the fuel pump has limitation if I am not wrong.

Oh and the torque losses at higher revs... adds to the wear and tear at these rpms.
Could you (or anyone else) explain all the above more lucidly ???

Do all diesel engines have a longer stroke than all petrol engines?

Torque losses at higher revs add to wear and tear?

What time isn't there for the stroked? Who stroked what? How long?

What limitations for the fuel pump? If the FP does have limitations, how does the engine rev to a certain rpm at all in the first place?
Quote:
Originally Posted by akshay1234 View Post
Generally a good number to replace synthetic would be 10k kms, but since you say you redline a lot I think 8-8.5k kms would be good. That is if your driving style is such a way that you redline it at least once or twice every time you drive (I do that). If its not then once a year or 10k kms is good.
Adding a little bit to the synthetic vs. mineral oil debate: The difference between synthetic and mineral motor oil.
Quote:
One of the biggest misconceptions in the synthetic vs. mineral debate is that synthetic oil lasts longer.
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Old 26th August 2011, 17:04   #98
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Default Re: Does Revving the Engine consistently damage the engine on a longer run ?

Quote:
Originally Posted by Kimified View Post
I have a i20 Diesel which i have been using from the past 9 months. I absolutely love the engine. Being a diesel, Its still quite Rev happy.
My advise would be to revv, taking into consideration the following things:

1.)Engine must not be cold (Drive sedately for 5-10 mins)
2.)You shouldn't stay in the red zone for too long (for eg. not shifting to 2nd & maintaining a steady 30 kmph)
3.) Touch the redline but don't let the car rev limiter 'hiccup' you back to reality.
4.) Clutch into a higher gear a bit slowly than you normally do. You don't need the engine jerking near the redline.
5.) Allow cooldown time for the last km (or two) of your journey, Drive sedately.

Consequences I've observed when frequently high revving are:

1.)Engine heats up after a spirited session(needle 1mm above half mark)
2.)Alternator belt squeaks & requires early replacement
3.)Smell of petrol (Engine running rich), very very rarely.
4.)ECU learns the lavish way & refuses to give me FE unless I reset it or drive with a feather light foot for a day.
5.) I haven't practically experienced this, but I was told by an SA at TASS that the clutch also wears faster when engaging at high RPMs

Last edited by JustCause : 26th August 2011 at 17:11.
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Old 26th August 2011, 17:25   #99
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Default Re: Does Revving the Engine consistently damage the engine on a longer run ?

I think if you are using the engine oil as per the manufacturer specification and are following the manufacturer specified oil change interval and are watching the other signs such as engine temperature religiously, there won't be any adverse impact on a high-revving engine.

If the manufacturer specifies using an engine oil of 5w30, changing the oil every 10,000 kms and the engine rpms from idle to redline are 800-4500, and I have been following the specifications, there's no reason why running the engine at 4000rpms every day should cause a problem. Yes, as some of the earlier posts have mentioned, constantly redlining the engine or high-revving it before it has warmed up sufficiently may cause premature wear and tear, but barring such conditions why should there be a problem?
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Old 26th August 2011, 17:25   #100
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Default Re: Does Revving the Engine consistently damage the engine on a longer run ?

To add to kimified's query, why is it that it is advised not to rev hard in first gear in a diesel? Also I have noticed, when the engine is revved above 2-2.5k in first gear, it kinda slots hard into 2nd. What is the reason for this?
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Old 26th August 2011, 17:32   #101
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Default Re: Does Revving the Engine consistently damage the engine on a longer run ?

Quote:
Originally Posted by SS-Traveller View Post
Do all diesel engines have a longer stroke than all petrol engines?

Torque losses at higher revs add to wear and tear?

What time isn't there for the stroked? Who stroked what? How long?

What limitations for the fuel pump? If the FP does have limitations, how does the engine rev to a certain rpm at all in the first place?
Do all diesel engines have a longer stroke than all petrol engines?
No not all but generally comparable capacity diesel v/s petrol, the diesel engines have longer strokes.

Strain on the engine components at higher revs are higher.

stroked ?? sorry spelling mistake Strokes.

Sorry my mistake about the fuel pump. I meant to say the injectors and then the spraying. they also limit the highest rpm to which the diesel engines rev.

Guys please pitch in to give more details.
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Old 26th August 2011, 18:07   #102
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Default Re: Does Revving the Engine consistently damage the engine on a longer run ?

Quote:
Originally Posted by figo_mba View Post
IF the best time to change synthetic oil is every 10K why is it that the manufacturers like Fiat ask us to come back in 15k kms only ?

Also, Does redlining damage the viscous properties of the engine oil ?
To be honest, if my Punto was driven the way I drive my Accord then I would change it at 10k kms. While the service intervals are good for normal usage, if your usage does involve stressing the engine then it would be a good practice to do things like change the oil a bit before the recommended time period. Also I think the amount of time between changing oil depends on the oil used and also the engine. I said 10k kms or 1 year as that is what I have generally seen is a safe interval.
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Old 26th August 2011, 21:16   #103
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Default Re: Does Revving the Engine consistently damage the engine on a longer run ?

In a properly engineered engine (bad pun), occasional redlining should do no harm whatsoever.

In diesels the way these are usually setup, there is normally no advantage in redlining.

On a matter of principle (actually rationalising what I enjoy) I fairly consistently redline my regular rides, petrol or diesel.

I don't abuse a car (I hope) but neither do I baby it. And no harmful effects to show for it.

Rev limit(ations) of diesels:- needs another thread.

Regards
Sutripta

Last edited by Sutripta : 26th August 2011 at 21:19.
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Old 26th August 2011, 23:13   #104
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Default Re: Does Revving the Engine consistently damage the engine on a longer run ?

I have read on this forum before that (1) engines are tested at red line for weeks at a stretch before the design is moved to production. Further, (2) all production engines are detuned anyways to improve service life. So occasional redlining should not cause any harm. There was a nice thread sometime back about over-revving which causes harm.

http://www.team-bhp.com/forum/techni...over-revv.html (All you enthusiastic drivers - DONT OVER-REVV)
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Old 27th August 2011, 01:43   #105
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Default Re: Does Revving the Engine consistently damage the engine on a longer run ?

Quote:
Originally Posted by humyum View Post
I beg to disagree with anyone here who says you can get the best acceleration by revving a diesel engine to 4 k + rpm's. If you rev till 4 k in 2nd gear, 3rd gear and 4th gear after the engine is out of the peak torque in case of the I20 must be around 3200 to 3400 you are just hitting a wall and slowing a progress without achieving much out of it.

For best acceleration its imperative to shift near the end of the torque band so that when you shift to a higher gear you are again in the meat of the torque band to make the most of the 21 kgm that the I20 produces.

For example if I revved my Swift diesel till 4 k in every gear, sure i ll be doing around 70 in 2nd and 100+ in 3rd but i ll be slower than what I could have achieved if I had shifted from 2nd to 3rd at around 55 and 3rd to 4th at around 85 and so on.
But what about the torque multiplying effect of the gears? AFAIK, both the Gearbox and the differential multiply the Torque going to the wheels. I've posted about the same on the first page.

Quote:
Originally Posted by figo_mba View Post
I agree. Since there is a lot of compression needed the parts are heavy and so at higher rpms the torque losses are also higher. Also a longer stroke (than gasoline engine) prevents the diesel engine being more rev happy. Long stroke mean more distance between TDC and BDC and so there is a certain distance to be covered for every stroke. As revs increases diesel engine just cannot cope because time is just not there for all the stroked. Even the fuel pump has limitation if I am not wrong.

Oh and the torque losses at higher revs. I think this adds to the wear and tear at these rpms.
AFAIK, for two engines of the same displacement and technology, longer stroked, smaller bore engines rev a little less than a shorter stroke larger bore engine. I'm not good with the details at all but I think it had something to do with the piston speed and thermodynamic efficiency. So, if the speed of the moving parts remains the same - except that the cycle occurs more often in a short stroke engine, will this contribute to higher wear and tear? Can anyone please explain the physics behind this?

Also, what are the torque losses at higher rpms that you are referring to? And how do these losses contribute to wear and tear directly? Please correct me if I'm wrong but here's how I understand it -
1. Inertial losses in engine - These are losses occurring before the crank. But since torque is measured at the crank, these are accounted for.
2. Losses in the drivetrain - Vary widely with engine, capacity, gearbox, final drive, drive (FWD, RWD etc.). According to Rototest, these average at 7% for FWD cars and 9% for RWD cars when torque is measured at wheel hubs. Although, I'd assume that losses for most indian cars would be higher as they have a lower horsepower rating and some loss is an absolute values. These should increase with rpms but I'd think the difference would be negligible (don't have any concrete evidence for this statement though)
3. Steady-state vs Acceleration - Measurements under acceleration will give lower results than measurements under steady state. This is because under acceleration, some energy will have to be expended to overcome inertia. I would think these would increase with rpms but some evidence suggests otherwise.
White Papers - Rototest Research Institute
The graph we need is in page 2 of part 2.

In any case, I don't see any significant increase in torque losses at higher rpms. Also, I don't see any direct link between torque losses of any kind and wear and tear. I could be very wrong though. I'll be happy to be corrected. Thanks

Quote:
Originally Posted by Kimified View Post
My average shift rpm is between 2.8 - 3k rpm. I do go upto 3.5 and 4k many times though (Like when i want to get away faster of the line from a signal or while overtaking on a highway). But its still pretty high compared to what other people shift at.
I drive my Vista TDi the same way. I shift at about 4600rpm as the torque drop off is pretty steep beyond that point.

Quote:
Originally Posted by Kimified View Post
Yeah. I am out of the Torque band. But i still feel the car pulling faster than what it would if i would have shifted it to a lower gear.
I do believe you are right. This would be because a larger gear (as in 1st gear ratio > 2nd gear ratio) acts as a torque multiplier. Hence, more torque would be going to the wheels at high rpms in a lower gear when compared to the peak torque band in a lower gear. Actually, to get the best acceleration, you have to go till the redline. This is almost always true except in case two gear ratios are very close to each other.

Take a look at this picture


Notice where the lines between one gear and the next cross. That's the best place for you to shift to get the most out of your engine.

The original document is here. I made it as an experiment

https://docs.google.com/spreadsheet/...l=en_US#gid=23

Quote:
Originally Posted by Added_flavor View Post
To add to kimified's query, why is it that it is advised not to rev hard in first gear in a diesel? Also I have noticed, when the engine is revved above 2-2.5k in first gear, it kinda slots hard into 2nd. What is the reason for this?
I've never heard this before. Where did you read this advice? I'd like to know the reasoning behind this.
And, what exactly do you mean by "slots hard into 2nd". I could be wrong but one possible reason is that it takes longer for the engine revs to drop to the right rpms in 2nd
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Last edited by nukeblitz : 27th August 2011 at 02:01.
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