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Old 27th May 2016, 13:57   #106
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Default Re: What happened to low end torque of today's small cars?

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Originally Posted by antz.bin View Post
It has more to do with the stroke length and less to do with the no. of valves per cylinder.

Higher no. of valves help the engine breathe better at higher revs, boosting peak power outputs but low end remains practically unchanged either way.

As I give the following stroke length data, you will surely find a pattern given that all these engines are naturally aspirated.

Polo 1.2 MPI : 86.9mm
Tiago Petrol : 85.8mm
Suzuki K14 : 82mm
Suzuki K10 : 79.5mm
Spark 1.0 : 77.4
Grand i10 Petrol : 75.6mm
Suzuki K12: 72mm
Honda Jazz : 71.58mm
I will comment about the cars I have driven. Among the longer stroke cars, the K14 and Polo have good low end torque. The K10 features in the middle but has pathetic low end torque. Spark is right below it but has very good low end. Similarly K12 and the 1.2 Kappa have better low end than the Honda 1.2. So, I don't find any pattern here unless we also bring in gearing into the picture which might also play a role in driveability.

Last edited by ashis89 : 27th May 2016 at 14:15. Reason: Spell check
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Old 27th May 2016, 13:58   #107
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I am driving Grande Punto 1.4 77 ps FIRE petrol engine in Germany. My daily drive is 25 kms with apprx 6 km inside city and the rest in country roads.

I normally shift at 2000 rpm and won't exceed 2500 rpm during the entire trip. My avg FE is 12.5 kmpl.

If I drive in Autobahn at an avg speed of 130 kph ( apprx @ 4500 rpm) then my avg FE is 14 kmpl.

But my assumption was other way around that driving with less rpm and higher gear will give maximum FE.

Is it due to the reason that I am driving in lower torque band and hence my FE is low?
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Old 27th May 2016, 14:28   #108
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Default Re: What happened to low end torque of today's small cars?

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Is it due to the reason that I am driving in lower torque band and hence my FE is low?
It seems that 2.5k-3.5k RPM is the optimal band for your Punto. Within this band, your car develops enough torque and HP to keep you and your pocket happy.

Moreover, the number of gearshifts required in city is much more than on the highways.

Last edited by Divya Sharan : 27th May 2016 at 14:29.
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Old 27th May 2016, 15:11   #109
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Default Re: What happened to low end torque of today's small cars?

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If i try to move to gear 2 with less RPM of gear 1, then comes this low end torque issue and the car behaves as if the engine is dead and it is very frustrating.
Absolutely. I drive Brio and have the same problem. Below 1k rpm and in 2nd gear, engine has no response even if you stand on the accelerator. And to make it worse, i cant slot in 1st gear until the car comes to halt. It is really a pain to drive it in slow moving traffic. Can anything be done? like remapping ECU ?

But as some one mentioned in the above post, reverse gear is peppy. Why cant the same be done to the 1st gear? OR is it the gear ratios? Some one please enlighten.

Best Regards!
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Old 27th May 2016, 15:19   #110
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Default Re: What happened to low end torque of today's small cars?

If you want low end torque these days, buy a turbo petrol car. I'm convinced the future is bright at least in the medium term for direct injection turbo petrol engines - until electrics pick up steam. These modern turbo petrols (fiat and tata turbo petrols are not in that list) offer a ruler flat, linear torque curve from 1500 rpm almost all the way to red line which makes them really easy to drive in traffic.

Having had a Brio for a while now, I am terribly bugged by the lack of low end grunt in the car. You have to rev the nuts off the car to get any sort of momentum - especially when there are other people onboard. On top of that, the notchy gearbox doesn't help. Am selling it for a turbo petrol.
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Old 27th May 2016, 15:27   #111
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Default Re: What happened to low end torque of today's small cars?

I am glad I found the thread. Since Sept 2015 I have a i10 Grand. I simply was confused and disenchanted about the low end torque in the car. I came back to a hatch back after nearly 15 years and was terribly frustrated about this. The problem compounds when you prefer it for its size and nimbleness in today's city traffic conditions, but are always left disappointed with the low end torque. The thing that takes the cake is both my father and wife who share the car between them when they drive personally ended up complaining the lack of 'Power' in the car !

I miss the low end torque in an otherwise decent product.
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Old 27th May 2016, 15:42   #112
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Default Re: What happened to low end torque of today's small cars?

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Absolutely. I drive Brio and have the same problem. Below 1k rpm and in 2nd gear, engine has no response even if you stand on the accelerator. And to make it worse, i cant slot in 1st gear until the car comes to halt. It is really a pain to drive it in slow moving traffic. Can anything be done? like remapping ECU ? !
Yes Nithi.
But, I am not a master of talking about remapping ECU.
Infact I am getting habituated in revving the engine more in first gear before moving to second and it is fun to the ear in revving this i-vtech.

Can anyone suggest us regarding the ECU remapping ?
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Old 27th May 2016, 16:38   #113
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Default Re: What happened to low end torque of today's small cars?

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Originally Posted by ashis89 View Post
I will comment about the cars I have driven. Among the longer stroke cars, the K14 and Polo have good low end torque. The K10 features in the middle but has pathetic low end torque. Spark is right below it but has very good low end. Similarly K12 and the 1.2 Kappa have better low end than the Honda 1.2. So, I don't find any pattern here unless we also bring in gearing into the picture which might also play a role in driveability.
As per your own experience, the K10, is the only one which doesn't confirm to the trend. This particular exception could be attributed to the gearing. Rest of the group stay true to the given order of stroke lengths.
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Old 27th May 2016, 16:50   #114
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Default Re: What happened to low end torque of today's small cars?

Doesn't variable valve technology play a significant role in low torque as well?
Best example is the first 1.3 Swifts and the 1.2k series engines on the present Swifts.
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Old 27th May 2016, 20:28   #115
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Default Re: What happened to low end torque of today's small cars?

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Doesn't variable valve technology play a significant role in low torque as well?
Best example is the first 1.3 Swifts and the 1.2k series engines on the present Swifts.
Weren't the 1.2 K-series also available without VVT for a while? Current Marutis with the 1.2 VVT engine are noticeably less peppier than their previous avatars.

No argument the G13 series engines were one of the best small block NA petrol motors. Aren't they still doing duty on the Gypsy?

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Old 27th May 2016, 20:44   #116
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Default Re: What happened to low end torque of today's small cars?

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Originally Posted by Chetan_Rao View Post
Weren't the 1.2 K-series also available without VVT for a while? Current Marutis with the 1.2 VVT engine are noticeably less peppier than their previous avatars.
Yes, the gen-I Ritz is peppier in lower gears than the current gen Swift.

Quote:
Originally Posted by Chetan_Rao View Post
No argument the G13 series engines were one of the best small block NA petrol motors. Aren't they still doing duty on the Gypsy?
Yes, they are used in Gypsy, and its 1.2L version is doing duty in Eeco. further more, the Eeco engine is very much peppier than the 1.3L gen-I Swift (not sure it is because of the light weight of Eeco).
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Old 27th May 2016, 21:02   #117
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I always have been a fan of cars with a good low end performance. And I feel the following hatchbacks available today offer the desired performance-

1. Cars with k12. It may not be rev happy or mod friendly like the g13bb but it does offer terrific low end performance.

2. 1.2L kappa engine. I find it best in the i10/grand i10.

3. 1.2L i-vtec in the brio. Probably the only Honda petrol with decent low end. The Jazz disappoints me in this regard.

4. GT TSi- 1.2L TSi enough said

5. K14- I am not a big of this engine but have to agree that it does offer decent low end performance.

I personally feel variable valve timing makes a lot of difference. Turbo-petrols (excluding tjet and revotron) are the way to go.


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Old 27th May 2016, 21:37   #118
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Default Re: What happened to low end torque of today's small cars?

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Originally Posted by Doylthippo View Post
Infact I am getting habituated in revving the engine more in first gear before moving to second and it is fun to the ear in revving this i-vtech
Thanks for the suggestion Doylthippo. You can do this when you start from stand still. But imagine when you are crossing a speed breaker, you cannot slot into 1st gear and 2nd gear is dead. And all the taxies will zoom past, giving a stare, thinking I am blocking the way.

And I am not used to revving the car while releasing the clutch. I completely release the clutch and then only press the accelerator, which will make it even more sluggish.

Best Regards!
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Old 28th May 2016, 08:22   #119
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Default Re: What happened to low end torque of today's small cars?

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Originally Posted by Chetan_Rao View Post
Weren't the 1.2 K-series also available without VVT for a while? Current Marutis with the 1.2 VVT engine are noticeably less peppier than their previous avatars.

No argument the G13 series engines were one of the best small block NA petrol motors. Aren't they still doing duty on the Gypsy?
I thought the K-Series always had the vtec on the intake side. I haven't driven the intital K-Series, so not sure. Do the new Swifts have vtec on both sides?

My father has a car from the first batch of Swifts and it is still so much fun after 11 years!

Another example is the previous gen Figo Petrol engine and the one on the new ones which has vtec.
The older ones were not all that great on the power front, but did have enough low end grunt which is missing on the new ones.


..........................................

Regarding the number of valves per cylinder discussion, here is an informative video;


Last edited by tharian : 28th May 2016 at 08:27.
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Old 29th May 2016, 10:15   #120
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Default Re: What happened to low end torque of today's small cars?

From what I read long ago, for a given engine the total area under torque curve is more or less constant for various tunes. Broadly there are three types of tuning

1. Normal tune of a street car is a compromise between power and FE. There is a decent torque at cruising speed which results in a good FE. This gives the car an average acceleration but decent FE.

2. flatten the torque curve - reducing peak torque but increasing it at both ends so that there is a substantial low end torque. This gives better FE, as well as better drivability at low RPM. Due to flattened torque curve lesser gears are required.

3. Peak the torque curve - increase the torque to upto twice the normal torque, but at the expense of reduced torque at the low end. This gives more power at the higher end at the expense of low end drivability. Mostly used for increasing high speed performance.

1 is what we get in an average car.
2 is rarely done today, except for special vehicles for off-road use, where low end torque is necessary. In the earlier days this was a popular tune for large saloons, to the extent that one manufacturer of a vehicle with a straight eight engine claimed that you could start at, and reach the top speed in the top gear!
3 is the most populat tune to increase the (high speed)performance

The newer petrol engines in small cars are being tuned for higher torque at higher RPM for
. More power at high speeds. As power(approx) = Torque x RPM, more torque at higher RPM = more HP to be bandied around by the manufacturer.
. Higher revving results in better AC performance as well as more power from alternator
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