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Old 26th February 2009, 08:10   #91
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For guys who believe in lugging in 5th gear and accelerating smoothly to achieve fuel economy, here is a myth buster. In 5th gear the acceleration will be very less compared to say, 2nd gear. In a lower gear you can achieve the desired cruising speed faster which means you reach your destination faster. This is illustrated in the figure below.

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In the figure above, the area under each curve gives the distance covered in a particular time. The area under the red curve is more which means you can cover a greater distance within the same time, and without increasing the cruising speed.
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Old 26th February 2009, 08:22   #92
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Now that we're done talking about lugging - maybe we should talk about how high RPMS actually dont really do any damage... lol

I had a car with 140k miles on it. I drove the piss out of that thing and the engine was clean as a whistle with absolutely no engine problems.

High rpms (up to redline) will no cause any problems if the motor is build to spec.
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Old 26th February 2009, 09:00   #93
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Quote:
Originally Posted by rippergeo
I'm still not sure if I have been lugging. can someone answer that please? The car does never did shudder/lag or vibrate when it was driven in 3rd gear at idle. I have been going by feel rather than using the tacho, till I saw this thread.
If you did not get any signals from the engine (shudder, vibrations etc), I would think no lugging is involved in your previous style of driving. Regarding the FE, I would think it better to make an assesment after atleast 2-3 more tankfuls with this new driving style. A 1kmpl increase is significant, but before we attribute it to the changed driving style, it would be good to check if it was just a one-off thing or consistent.

Quote:
Originally Posted by Eddy
Unsuitably low or high, both should be avoided.
Yep, this would be what needs to be kept in mind rather than remembering some specific rpm at which to change gear. Extremes on either side can be bad. It is not rocket science to make sense of the feedback the engine gives you and this can be done even without a tacho.

Quote:
Originally Posted by watashi75
For guys who believe in lugging in 5th gear and accelerating smoothly to achieve fuel economy, here is a myth buster. In 5th gear the acceleration will be very less compared to say, 2nd gear. In a lower gear you can achieve the desired cruising speed faster which means you reach your destination faster.
You start off with acceleration, then go to economy and finally end up at 'reaching home faster'. Those who actually lug their engines or others who drive at the optimum speed for each gear are not really bothered about reaching home faster. Mostly the idea is better FE or avoiding gear changes.

And again in a city, you could be driving a Ferrari and redline all the gears, but since we have the big leveller called the traffic light, at the next light you would be staring into the face of the guy on his M800.

Quote:
Originally Posted by Atlblkz06
I had a car with 140k miles on it. I drove the piss out of that thing and the engine was clean as a whistle with absolutely no engine problems.
This is again like what GTO mentioned earlier about someone he knew who did not do oil changes for 25K kms and yet the car was running. Does not prove anything. I have seen a fully empty oil reservoir on a CT100 bike. And still running. Does that mean we can all forget the oil change every 3K kms on our bikes ?

Quote:
Originally Posted by Atlblkz06
High rpms (up to redline) will no cause any problems if the motor is build to spec.
The same thing can be said about those who actually 'lug' their engines. I do not believe that an engine will fail just because someone lugged it. I do know that it is not a good practice and personally don't do it, but if it is someone's choice to lug an engine, irrespective of all 'thermal loading' and stuff mentioned here, I can bet that it won't fail.
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Old 26th February 2009, 11:28   #94
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Quote:
Originally Posted by Atlblkz06 View Post
Now that we're done talking about lugging - maybe we should talk about how high RPMS actually dont really do any damage... lol

I had a car with 140k miles on it. I drove the piss out of that thing and the engine was clean as a whistle with absolutely no engine problems.

High rpms (up to redline) will no cause any problems if the motor is build to spec.
As long as one takes due precautions - like allowing the engine to warm up, change engine oil/filter, high rpms regularly would not harm the engine much. Continuously - maybe. The biggest problems are peoples old habits - as soon as the engine is started, most drivers/owners start to rev the hell out of it in neutral - they think they are charging the battery. This is the surest way to ensure your engine will last only 60k km.

Lugging is quite bad for the engine too - especially when new.

In this context, possibly an AT would prolong the life of the engine?
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Old 26th February 2009, 11:53   #95
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My personal experience:
Lugging decreases the fuel consumption whoppingly, but it also makes the car a laggard.

In my experience - the traffic in Pune compells me to drive in 2nd and 3rd gear most of the time (with comfy revs). getting me around 9-10 kmpl on OHC VTEC.

On highways my experience is total different - getting 18-20 kmpl.
The reason - driving in 5th gear as much as possible.

Driving in 5th gear allows you car to move more per liter of fuel consumed by the engine.
Its a simple fact, and no one can deny that if your engine is running (i.e. it doesn't die out, and is generating sufficient torque to keep it rolling without jerks), driving on highest possible gear will make the car run more distance for the same RPM engine is maintaining.

Last edited by alpha1 : 26th February 2009 at 11:55.
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Old 26th February 2009, 12:20   #96
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18-20kmpl on highways is way to good dude. is it with the ac on? and howmany people in the car??

i just got 14kmpl with 5 people and 100% ac.

Quote:
Originally Posted by alpha1 View Post
My personal experience:
Lugging decreases the fuel consumption whoppingly, but it also makes the car a laggard.

In my experience - the traffic in Pune compells me to drive in 2nd and 3rd gear most of the time (with comfy revs). getting me around 9-10 kmpl on OHC VTEC.

On highways my experience is total different - getting 18-20 kmpl.
The reason - driving in 5th gear as much as possible.

Driving in 5th gear allows you car to move more per liter of fuel consumed by the engine.
Its a simple fact, and no one can deny that if your engine is running (i.e. it doesn't die out, and is generating sufficient torque to keep it rolling without jerks), driving on highest possible gear will make the car run more distance for the same RPM engine is maintaining.
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Old 26th February 2009, 12:21   #97
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What do you exactly call the opposite of Lugging ?? Redlining. ?
I'm mostly not in that lugging zone thanks to the mad car

BTW here's another query !!

For those who don't know, i drive a Getz CRDi : 130bhp @ 4000rpm and 275Nm @ 1900rpm. My daily drive involves 50kms of expressway where i'm mostly cruising at around 150 kph range. I change to 5th gear @ 100kph and from there on i do speeds anywhere in the range of 100-200kph in the same gear where the rpm goes from 2000 - 4500rpm. The redline is at 4500rpm.

So, does going till the redline in the top gear also mean redlining ?
My perception of redlining is revving to redline in each gear or Am i wrong?

Last edited by kpzen : 26th February 2009 at 12:30.
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Old 26th February 2009, 12:26   #98
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@alpha1, let us leave the 5th gear & highway combination out of this discsussion. That would qualify as OT to the subject of this thread.
Quote:
rippergeo : My last few tankfuls have given me 16.5 to 16.7 in the city with the AC on.
This while "lugging"(idle in 3rd gear)
@Ripper, your points can make sense if you can specify which car you are refering to. Nobody is going to dig out details of your ride to understand what you are saying.

Quote:
Shan2nu : My cousin's Indigo Diesel which has never been revved hard, failed at very low rpm.

I asked him how it happened and he told me that he was in 5th gear and the moment he used full throttle to overtake, the engine made some sound and died out.

The bill has come to around 25K and they have filed a case against TATA.
I would say bad handling / driving. And I dont see much hope in this case - you will need to prove that it was mechanical failure due to manufacturing defects. And even then, Tata may at the most need to repair it under wty.

He was in 5th gear - at very low rpm (see first two points of your post here). Essentially, lugging. The engine was not at a point where it could have pulled up itself fast enough. Something gave in that day. Possibly because of doing that over a long period of time - top gear, low rpm.

Last edited by condor : 26th February 2009 at 12:41. Reason: Responding to 2 more posts.
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Old 26th February 2009, 13:07   #99
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@condor, I think rippergeo is talking about his DDiS.

Hey kpzen, drive safe man. The mere thought of driving at 200kmph on Indian highways makes me ****-scared.

Quote:
Originally Posted by kpzen
My perception of redlining is revving to redline in each gear or Am i wrong?
You are right and that is how almost all of us would mean it when we use the term redlining.

In most modern cars, as per my understanding, we cannot technically redline the car (as in achieving the rpm in the red band area, which I guess lead to the coining of the term redlining) because after the set allowed limit, there is a limiter that is hit. So, while we use the term 'redline' frequently, we are not actually hitting the redline area (which in my Baleno is above 6500rpm). I can go till max 6500rpm and thats about it.

But if someone somehow (I am sure there are ways for it) removes the limiter and you go beyond the permitted max of 4500 in your Getz, you are actually 'redlining' in the true sense of the word. And this could be dangerous for the car. In your case, I don't think hitting 4500rpm is anything bad (not counting the low FE) because it is anyway permitted by the manufacturer.

Last edited by supremeBaleno : 26th February 2009 at 13:09.
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Old 26th February 2009, 13:14   #100
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Quote:
He was in 5th gear - at very low rpm (see first two points of your post here). Essentially, lugging. The engine was not at a point where it could have pulled up itself fast enough. Something gave in that day. Possibly because of doing that over a long period of time - top gear, low rpm.
Yup, and thats another mistake people make during the run in peroid. They just make sure that the rpm doesn't rise above a certain figure while going full throttle in higher gears. This isn't helping at all.

This car has been driven like this from day one.

Shan2nu
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Old 26th February 2009, 13:15   #101
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Quote:
Originally Posted by supremeBaleno View Post
I don't think hitting 4500rpm is anything bad (not counting the low FE) because it is anyway permitted by the manufacturer.
Guys, no engine that I have driven felt 'happy' at redline! Screaming. Is that the word?
Surely this leads to accelerated wear of components?
It may be the maximum allowed by the maker, but there is a difference between the maximum allowed and the ideal recommended.
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Old 26th February 2009, 13:32   #102
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Quote:
Originally Posted by condor View Post
@Ripper, your points can make sense if you can specify which car you are refering to. Nobody is going to dig out details of your ride to understand what you are saying.
It was the Swift DDiS with the tuning box, and I had said so earlier in the thread. Shall start putting up that info in my signature from now on.

Question
Thermal overload takes place irrespective of whether the car is jerking/shuddering/lagging when it is driven in high gears at near idle rpms
Is that true or not?

That would tell me for sure if I should change my driving style or not.

@anupmathur- ever tried the OHC VTEC? it sounds plenty happy near the redline, and even happier bouncing off the rev limiter. There is accelerated wear and tear, yes, but some engines are built to take that kind of wear and tear better than the damage caused by lugging.

Last edited by rippergeo : 26th February 2009 at 13:36.
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Old 26th February 2009, 13:55   #103
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Quote:
Originally Posted by rippergeo View Post
@anupmathur- ever tried the OHC VTEC? it sounds plenty happy near the redline, and even happier bouncing off the rev limiter. There is accelerated wear and tear, yes, but some engines are built to take that kind of wear and tear better than the damage caused by lugging.
Ripper, I agree more or less with what you are saying, but when you try just the OHC alone, I'd say there is a very willing and free revving engine. However, even that one does not sound as happy as it does at 3000-4500!
Heck, at these rpms it is almost 'absent', in that you can barely know it is there, LOL!
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Old 26th February 2009, 14:00   #104
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Talking about Redlining and wear on parts - Bentley use gearboxes made by ZF, recently on testing one of their cars the engineers at Bently were a bit worried by the fact that one of their engine simulations disinigrated into pieces after running flat out for about 40mins. But in the real world - a) The fuel tank would would last 20mins, whilst flat out and b) the cars have Rev limiters on them.

This just goes to show that the engines are over engineered to make sure nothing goes wrong in everyday use - But that does'nt mean theres no accelerated wear if you thrashing it all the time.

My Gypsy loves being around the limiter and so does the Subaru.

Last edited by Samir Taheer : 26th February 2009 at 14:18.
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Old 26th February 2009, 14:26   #105
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Quote:
Originally Posted by KSM-Vtec View Post
18-20kmpl on highways is way to good dude. is it with the ac on? and howmany people in the car??

i just got 14kmpl with 5 people and 100% ac.
No AC.
Two ppl only, and keeping the speed below 80 all the times.
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