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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 14th March 2011, 19:19   #31
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

Quote:
Originally Posted by LNK View Post
That being said, the cars 1.5 and 1.3 were targeted at different audience. Not the 1.5 Vtec and 1.5 exi, in my humble opinion.
I was comparing the 1.3(Vanilla) with the 1.5. You are right, they were positioned differently. But I quite like the idea of bringing in cars with different engine options on petrol as well as diesel. For eg. the Punto comes with the 1.2 or the 1.4 FIRE in petrol & the Indica Vista comes with Quadrajet & TDI engines (diesel).
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Old 14th March 2011, 19:27   #32
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

I have a Baleno and 4K is 140KMPH in 5th gear. Pretty much useless in daily drives. I notice that all my driving in town is mostly within 2.5 K.

Quote:
Originally Posted by LNK View Post
Alright, here's a mildly related question I have. I'd posted it elsewhere but no response.

If an engine is not revved high for a long time, say for years, does the engine lose its potential by an amount? Like, if the car's always been driven around at <3.5k rpm, will it be an issue if all of a sudden I push it and maintain it at 4.5k or higher? In short, do engines get lazy like humans?
My two bits on this!
Yes it does happen, but I think it more to do with the ECU. I give the car a blast when I notice that the car is reluctant to open up and the redlining seems to work.
Of course all this could just be in head.
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Old 14th March 2011, 19:27   #33
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

The problem which we are trying to relate is because we drive carburetted vehicles at one point of time. In the carb vehicles petrol consumption is directly proportional to the pressure drop in the venturi. So when you lug an engine it will consume the same amount of fuel at the same amount of throttle opening.
Now the MPFI engines are bit different. It uses various sensors like Lambda sensor, MAP, crank sensor, Trottle sensor. When you start the engine it will run the engine in open loop till lambda sensor provides signal to the ecu or the temp sensor provides the data whether optimum coolant temparature has been reached. Thats the reason Short trip drives often gives less milage because engine is running in open loop.
In the closed loop scenario when you lug an engine and knock sensor identifies a knock the ecu orders the injector to pulse little more fuel to avoid knocking. This fuel consumption may be more compared by lugging the engine rather than driving in proper gear. Also when the load sensor values are low injector will trim the fuel and increases FE.
Some drivers use coasting (ie) after certain speed they put back to neutral and coast. When the ecu identifies sudden drop in rpm it will instruct injector to push more fuel to keep the vehicle running results in less FE. You can get more FE by decelerating slowly as the fuel delivery will be cut during deceleration.
The only thing will increase FE consumption is during sudden accleration and hard deceleration.
I will narrate one incident where my friend was already getting tremendous FE (12 in city)from his 1.6 petra. He asked the mechanic and he shown him how to drive and get most FE. He quickly moved to second and third and the tacho shows barely 1500 rpm. A week later we got the city mileage to be 9.5 Kmpl. He used to change the gear in 2.5 ~3k rpm and he got 12 kmpl when he changed the driving behavior by lugging he lost his happiness and also FE.
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Old 14th March 2011, 23:22   #34
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

What a good topic, why cant we have more such discussions.

That 2-3k rpm is most suitable for gear changes is beyond debate, as most of you have pointed out. Very good FE is also achieved by this practice. My Ikon used to give 13+ in the city always by following this simple principle. Similarly in the Civic, too quick gear changes does no good to FE and robs the pleasure of driving. However gear changes at 4+k is still a rare practice for me. Trying hard to do that more often. General driving at 4+k is another story. Sometimes done to just hear the vtec sound. Otherwise maintaining 4k+ rpm in city is difficult since within seconds, some obstacle comes up.

Many times we have a mind block to find out what our cars can really do.

However I do find it hard to believe that ECU gets trained by our driving styles. Does it have adaptive logic? I dont know, I am hoping some of you can shed a light here.
Similarly whether an engine is running at 2-3k or 5-7k, coolant will make sure that engine and oil temperaure is similar. Why will deposits burn off at higher rpm?

Last edited by dot : 14th March 2011 at 23:25.
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Old 15th March 2011, 01:13   #35
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

Hi all,

IMO the RPM I'm at really depends on the situation.
I do not have FE as the most important factor at all points of time. I do like to strain the engine by shifting up too soon. I do want my car to be with me longer. Somehow, that makes more economical sense to me as well. .
In the city, in most situations, the engine does well in the 1.5 - 3.5 k range, with very far apart spurts to 4k.
On the highway, IMHO, it doesn't make sense to keep chugging at a low speed on a high gear, specially when overtaking. If need be I do down shift on the highway. But since I drive an M800, it is hardly ever required to do that, apart from where the speeds are lower than 50 kmph.
Having a good mid range seems to make more sense to me, as I do a lot of highway and semi-urban driving.

Cheers and drive safe.
Sam
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Old 15th March 2011, 03:11   #36
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

For the BSIII FIAT 1.25L Turbo Diesel, 2500 is max torque, 4000 is Max HP.
At 4000 RPM in fifth gear the car will be at an inidcated 160KMPH.

I love to drive between 3000 to 4000 RPM, if and when the roads permit.

Offtopic, you can go upto 4500 RPM, where it rides at an indicated 180KMPH.
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Old 15th March 2011, 08:46   #37
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

For the best fun to drive and best mileage is obtained in the max torque rpm range. It will give highest volumetric efficiency. Also you are always in the torque band hence over taking will be a piece of cake and you dont need to floor the pedal which decreases FE.
Yes. Ecu will note your driving style and adjust the engine behaviour as per the driving style.
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Old 15th March 2011, 10:03   #38
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

This thread was on my mind, and i tried the 3500-4500 band last night.
As i voted, I agree that its no use.
One-it takes a lot of noise to reach.
I DID learn on a non-tachoe'd car, and do switch by engine noise.
With my current ride, i see that it translated to switching at about 2.5-3.5 k.
Two-It was AWESOME!!Intoxicating!!FE be damned!
The surge, hitting the apparent sweet spot was phenomenal!
But i know that its no use in trafficked, mildly or other wise, roads.
Youre going to keep shifting to keep it there,and may even end up bashing the car..so, no thank you.
Ill keep it for UN-regular drives.

PS:its nice to know its there, though.
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Old 15th March 2011, 12:18   #39
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

Quote:
Originally Posted by Aroy View Post
Once the engine is revved up and driven for some time, the deposits normally burn up and the acids in the engine oil evaporate. That is why after a longish trip of say 100km+, or after spirited driving at 120+ for 20km the engine feels different with an aggressive growl as well as excellent throttle response.
Oh, yes! I've noticed that. So revving hard often is actually cleansing the engine more than doing it harm?

Quote:
Originally Posted by vijaycool View Post
For the best fun to drive and best mileage is obtained in the max torque rpm range.
Max torque in my car comes at around 4.6k rpm (OHC 1.5). Now I was in the opinion that for higher fuel efficiency I need t shift between 2-3k rpm. So the FUN part I agree, totally. But the efficiency?

Besides, in city traffic conditions if you maintain a high torque range you'll have to brake hard which in turn will take a toll on the car.

Quote:
Originally Posted by vijaycool View Post
Yes. Ecu will note your driving style and adjust the engine behaviour as per the driving style.
So, if one was to reset the ECU , by disconnecting the battery, what setting would it hold on reconnecting the batteries?

Quote:
Originally Posted by ssingri View Post
Yes it does happen, but I think it more to do with the ECU. I give the car a blast when I notice that the car is reluctant to open up and the redlining seems to work.
Of course all this could just be in head.
Exactly, I've noticed the same after long trips and enthusiastic driving sessions, again I wonder if its all just in the head or for real.
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Old 15th March 2011, 12:33   #40
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

Quote:
Originally Posted by mayankk View Post
This thread was on my mind, and i tried the 3500-4500 band last night.
As i voted, I agree that its no use.
One-it takes a lot of noise to reach.
I DID learn on a non-tachoe'd car, and do switch by engine noise.
With my current ride, i see that it translated to switching at about 2.5-3.5 k.
Two-It was AWESOME!!Intoxicating!!FE be damned!
The surge, hitting the apparent sweet spot was phenomenal!
But i know that its no use in trafficked, mildly or other wise, roads.
Youre going to keep shifting to keep it there,and may even end up bashing the car..so, no thank you.
Ill keep it for UN-regular drives.
PS:its nice to know its there, though.
If you are driving a Santro, I agree..I know how it feels like in a Santro. The upper rpm band is not much required. Moreover, the engine will start begging for mercy once you rev it up to 4K rpm. Its cry gets transmitted to driver's hand through the gear lever..

This is not the case with all engines though. There are very rev happy engines which will beg you to rev even more when you start revving up.

And, revving a petrol engine to 4K won't do any harm to it. Common misconception.

Last edited by clevermax : 15th March 2011 at 12:34.
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Old 15th March 2011, 12:39   #41
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Smile Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

i think it depends on the engine and make of your ride

i drive a Hyundai accent 1.5 petrol (or almost 1.5l i think) and i depend on engine braking(in city or on highways) all the time (i think fe is less important than safety) so it is ushuly some where between 2kand 3.5k rpm in city driving conditions and 3k-5k rpm on highways
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Old 15th March 2011, 12:39   #42
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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
If you are driving a Santro, I agree..I know how it feels like in a Santro. The upper rpm band is not much required. Moreover, the engine will start begging for mercy once you rev it up to 4K rpm. Its cry gets transmitted to driver's hand through the gear lever..

This is not the case with all engines though. There are very rev happy engines which will beg you to rev even more when you start revving up.

And, revving a petrol engine to 4K won't do any harm to it. Common misconception.
this is for a petrol fiesta.
Santro would hardly start blazing in that band.
Santro was the untacho'd car that i was talking about.
That had FFE, and could definitely be used as torture for hungover friends in the 2.5 to 4 k range.
(as well as a conscientoius driver....)
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Old 15th March 2011, 12:39   #43
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

In the city, there's no space to rev that much during the peak hours; may be an empty avenue at night with no traffic in sight. On the highway, better to get into overdrive as fast as possible, in interests of fuel efficiency. I favor relaxed style of driving, rather than hit the rev limiter on a regular basis.
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Old 15th March 2011, 12:42   #44
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

Quote:
Originally Posted by samarth.bhatia View Post
Hi all,

IMO the RPM I'm at really depends on the situation.
I do not have FE as the most important factor at all points of time. I do like to strain the engine by shifting up too soon. I do want my car to be with me longer. Somehow, that makes more economical sense to me as well.
If you are straining your engine by shifting up soon, you are not going to have the car with you 'longer'. Lugging the engine means lower engine life. Forget economical sense, it doesnt make any sense to me. Forgive the harsh tone, but it irritates me no end when I find people taking ages to overtake, lugging the engine etc. all in the name of FE. If you love your car, you would not do it.

It is like you have a pet dog. And you starve it, so that you can save some money in buying dog food. Always drive the car in the meat of the rpm range

@Samarth Bhatia - on other thoughts i feel you must have missed a 'don't' in your post. In that case, my post is not for you

Last edited by mallumowgli : 15th March 2011 at 12:44.
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Old 15th March 2011, 12:46   #45
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Default Re: Debate: >4k rpm band useless for regular driving and for regular joe drivers

it is quite boring to drive my car / switch gears at around 4,000RPM - i always shift at 2-2.5K rpm for fun and spirited driving.

only when i am feeling sad, i take it upto 3,000RPM in second gear, drive like that for a few seconds and dab the gas pedal further until the rpm reaches 5K and upshift and repeat the same for the third gear - i feel more sad and upshift to 4th and repeat. after that it feels scary and i slow down. it is not fun i tell you especially with windows rolled up and intake note taking care of in-car entertainment.

btw, last sunday, i filled 37litres of fuel when the trip meter was showing 260kms.

Last edited by planet_rocker : 15th March 2011 at 12:54.
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