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View Poll Results: Is above 4k rpm useless for regular driving?
Agree 76 54.68%
Disgree 22 15.83%
Depends on the situation 39 28.06%
Dont know 2 1.44%
Voters: 139. You may not vote on this poll

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Old 16th March 2011, 00:41   #61
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

There is a trick to make the engine responsive. After you start the car keep the revs to 4K for 10~15 secs then idle it for few secs and repeat once more. You have the responsive engine.
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Old 16th March 2011, 03:20   #62
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

Voted for Agree. Fully subscribe to the view that >4K RPM is uncommon especially in the city. It also probably explains the FTD factor of modern day diesels as the power and torque kick in quite early( Vento, Fiesta, Micra, Renault Diesels) and the stated one's minimal turbo lag. That does not take away the Diesel price advantage which is one of the main entry criteria.
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Old 16th March 2011, 12:48   #63
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

My 2.0 L Lancer Diesel feels pretty uncomfortable when I rev the engine above 3.5K. True. The RPM range above 3K is useless AFAIK and with respect to this Diesel engine.
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Old 16th March 2011, 13:04   #64
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

Quote:
Originally Posted by rangarx View Post
My 2.0 L Lancer Diesel feels pretty uncomfortable when I rev the engine above 3.5K. True. The RPM range above 3K is useless AFAIK and with respect to this Diesel engine.
Wouldnt this be true for all diesels?
AFAIK, torque peaks in diesel arrives much earlier in the revband.
pulling 3.5 k on a diesel peaking at 2k, wouldnt that equate to pulling a similar petrol block to , i dont know, near-redline?
I mean regarding the amount to the turtured-engine feeling.

Edit: I was trying to recall where i heard this first.Just remebered.
He's not the biggest authority on technicals, i s'pose, but the explanation was quite succinct.
It was JC when he took the Jag diesel(which one, would need to be googled) to the nurburgring, and was trying to lap it in 10(?) minutes.

Last edited by mayankk : 16th March 2011 at 13:11. Reason: addendum
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Old 16th March 2011, 17:39   #65
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

Even though I would love to do this in my OHC VTEC much often its practically not possible during regular driving. This is true for in city driving as well as highway runs.
At highway speeds of 120/140 kph engine rpm stays between 2500 - 3500 rpm in top gear.
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Old 18th March 2011, 16:05   #66
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

Quote:
Originally Posted by clevermax View Post
Gas pedal can be at different positions when engine rpm is the same in the same gear.

Example:

- You are driving on a horizontal surface in 4th gear with a light foot on gas, engine relaxing at 2500 rpm.
- You are driving up on a slight incline with heavy load in 4th gear, gas pedal pushed to the floor, engine lugging at 2500 rpm.

The second case will waste more fuel than the first. Hence, same gear, same rpm, no constant fuel consumption!
Thanx for putting this in so simple word and very lucidly

Case A): You are driving on a horizontal surface in 4th gear with a light foot on gas, engine relaxing at 2500 rpm.
Case B):You are driving up on a slight incline with heavy load in 4th gear, gas pedal pushed to the floor, engine lugging at 2500 rpm.

Quote:
Originally Posted by clevermax View Post
It can happen mostly when you are in neutral gear, but not in another gear under load. It will take some time for the rpm to climb up depending upon the load & power band of the engine.
Therefore
Neutral : No load, minimum fuel consumption for a given RPM (say 2500)
Case A): Moderate load, moderate fuel consumption for that given RPM.
Case B): Maximum load, minimum fuel consumption for that given RPM.

So, we can further analyse the pro and cons of higher RPM vs Fun to drive correlation more easily.

Cheers
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Old 18th March 2011, 16:27   #67
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

On my 1.4 Corsa, I reach 100 km/hr at just 3k rpm on the 5th gear. I'm wondering what road I can actually get the engine to 4k rpm!

Most stretches in B'lore where one CAN speed up have interceptors and speed limits range from 60-80km/hr. So, the >4k band is pretty much left unused.
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Old 18th March 2011, 17:00   #68
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

^^It's much more fun in the same car to reach 100km/h in 3rd gear@5000rpm. I've done 120 on the 3rd and 150 on the 4th. The 5th gear is too tall.

Its not how fast you go, it's how much fun you have getting there
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Old 18th March 2011, 17:50   #69
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

Quote:
Originally Posted by cranky View Post
^^It's much more fun in the same car to reach 100km/h in 3rd gear@5000rpm. I've done 120 on the 3rd and 150 on the 4th. The 5th gear is too tall.

Its not how fast you go, it's how much fun you have getting there
Agreed. But, how often have you done it during "regular" driving?

On an average routine day (on a city stretch), I doubt one would actually drive at that gear-rpm.
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Old 18th March 2011, 18:08   #70
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

Absolutely right about that, in-city driving you will probably never reach that sort of rpm or speed.

But that is the point. The 4K range is a car's 'party hat', if there were one. And a car that does not have it, is as boring as a real person who can't have a good time once in a while
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Old 18th March 2011, 18:43   #71
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

I voted for "I agree".

But then I realized that, it holds good only for my car. For bike, I am always above 4K
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Old 18th March 2011, 18:48   #72
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

Quote:
Originally Posted by cranky View Post
But that is the point. The 4K range is a car's 'party hat', if there were one. And a car that does not have it, is as boring as a real person who can't have a good time once in a while
Well said.
Even during regular driving and commutes one does get opportunities to rip and blast.

One second thoughts, this may not be applicable for Bangalore.
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Old 19th March 2011, 01:50   #73
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

There's a post somewhere on this topic that the band over 3k rpm in a diesel is useless. I disagree.

I'm making the assumption that the diesel makes max power at 4k rpm (although in a lancer diesel, i think it's 4.5k)

In any case, the important thing to consider here is the torque multiplier that a lower gear provides. So, even though the peak torque might be produced might be between 2k and 3k rpm, the torque multiplier ensures that, usually, that lower gear will provide better acceleration till well after the peak power point.

I have a few graphs and spreadsheets that i have prepared to support this. I'll put them up when i can sit in front of a computer.
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Old 19th March 2011, 09:52   #74
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

Yes very true. I hardly ever reach above 3.5k forget 4k and all my cars are petrols. I really wonder whats the need to drive road going non racing hatchbacks and sedans that majority of us own above 4k which is not really the intended purpose of these cars. Capabilities above 4k are good to have not a must have.
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Old 19th March 2011, 09:59   #75
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

Travelling > 4K rpm a top gear will give too much speed even on highways. We need to alter the driving style and limit the gear usage till 3rd gear. Good drivability will come below max torque rpm and also mileage.
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