[Shome]

Originally Posted by pgsagar

BTW, the ratios are very interesting. AT's 1st gear is near MT's 2nd. AT's 4th at 0.698 is way more overdrive than MT's 5th at 0.815. This means AT should be more fuel-efficient at 4th than MT at 5th. Good for me.

But as you said limited only to the fifth. Acceleration for the MT would be faster.

Also, the gear ratio would mean that you can reach the same or even higher speeds than the manual. Am I correct?

[Mr_Bean]

Originally Posted by Shome

The expressway surprisingly gives me about 17-19 with speeds of around 140 kmph

Thanks a million for the remainder of the post. This was helpful

My colleague also get such fuel efficiency at 130+ km/hr speeds, this just beats my thought. If true then 23-24 km/hr is very much achievable with speeds of 80-90 kms/hr on an a-star.

[pgsagar]

Originally Posted by Shome

But as you said limited only to the fifth. Acceleration for the MT would be faster.

Also, the gear ratio would mean that you can reach the same or even higher speeds than the manual. Am I correct?

Hmmm.... You have a point here. Taking these ratios into account, AT should be slightly faster and more fuel-efficient. Next time I hit highways, I would note both FE and top speed.

[.anshuman]

Originally Posted by Shome

Hey again.
This is what I know of as I had the same question earlier

4 Speed Automatic Transmission

• Forward Gear Ratios: 1.875 , 1.568, 1.000 and 0.698 respectively
• Reverse Gear Ratio of 2.300

Source: Maruti A Star Automatic Price In India - Specifications Features And Color Options

5 Speed Manual Transmission

• Forward Gear Ratios: 3.454 , 1.904, 1.28, 0.966 and 0.815 respectively

Hope this helps.

Are the final drive ratios same for these versions? Final drive ratios need to included in the calculation.

The AT comes with a power sapping torque convertor, it may not return higher FE than MT even with taller ratios.

[pgsagar]

Originally Posted by .anshuman

Are the final drive ratios same for these version? Final drive ratios need to included in the calculation.

The AT comes with a power sapping torque convertor, it may not return higher FE that MT even with taller ratios.

Yes, we missed a crucial point here. Final Drive ratios need to be factored in, too. But if both have same F.D. ratio then they are on level playing field. However, as you have righly pointed out, torque convertor does indeed sap some power. So, looks like MT will be faster and more fuel-efficient, after all. However, AT's 4th which is more overdrive than MT's 5th will compensate and will put both on more or less on even keel. So, torque of A-Star engine shouldn't be all that bad to handle such a huge overdrive of 0.698.

[Shome]

Originally Posted by .anshuman

Are the final drive ratios same for these version? Final drive ratios need to included in the calculation.

The AT comes with a power sapping torque convertor, it may not return higher FE that MT even with taller ratios.

Hey Anshuman, to be honest I have no clue. I just picked it off the site mentioned in my source. I am not at all technically sound

[Guna]

Originally Posted by .anshuman

The AT comes with a power sapping torque convertor, it may not return higher FE than MT even with taller ratios.

Add to that, automatics weigh more (at least by 50 kgs)

[humveeguy]

That brings to the point of how to reduce the gross weight say 50 to 100 Kgs ? Any redundant items in this hatch ?

HG

[ash_blore]

The past few posts have spoken about torque converters and I went and found this link

HowStuffWorks "Torque Converters Benefits"

It says that one way to improve the eff of the mechanism is to have a lockup clutch (based on how well the article is written its easy to understand why it would help).

Do we know if the ATs in India (i10/A*) etc come with such lockup clutches inside the T-converter?

[blackasta]

Originally Posted by ash_blore

The past few posts have spoken about torque converters and I went and found this link

HowStuffWorks "Torque Converters Benefits"

It says that one way to improve the eff of the mechanism is to have a lockup clutch (based on how well the article is written its easy to understand why it would help).

Do we know if the ATs in India (i10/A*) etc come with such lockup clutches inside the T-converter?

In all probability - no. The Honda 5 speed AT gearbox might have that.

[Guna]

Originally Posted by blackasta

In all probability - no. The Honda 5 speed AT gearbox might have that.

I also think so but not sure. When you use 'sports mode with paddle shift', typical elastic feel of the AT is gone and it feels direct as if it has mechanical clutch. But even then the FE goes up only by 0.5 kmpl which indicates clutch lock up may not happen.

[blackasta]

Originally Posted by Guna

I also think so but not sure. When you use 'sports mode with paddle shift', typical elastic feel of the AT is gone and it feels direct as if it has mechanical clutch. But even then the FE goes up only by 0.5 kmpl which indicates clutch lock up may not happen.

The sports mode has nothing to do with the 'mechanical clutch'. AT cars with torque converters do not have a mechanical clutch per se. Its all about varying the shift points in S mode.

[Guna]

Originally Posted by blackasta

The sports mode has nothing to do with the 'mechanical clutch'. AT cars with torque converters do not have a mechanical clutch per se. Its all about varying the shift points in S mode.

What I meant was, in sports mode it seem to lock up the torque converter which gives the feel of a mechanical clutch (rigid, no winding- unwinding)

[k_nitin_r]

Originally Posted by pgsagar

Did you say 140 kph? Are you serious? Can A-Star do these speeds? Or for that matter petrol hatches of this class do these speeds?

The Maruti 800 can go at upto 130 kph and if you do have a long straight road, you just might be able to manage 140 kph. I'm sure that other hatchbacks such as the Maruti A-star can reach these speeds too.

As long as you have a 5-speed MT, it is safe to assume that your vehicle can handle speeds upto 120 kph on 5th gear without rpms high enough to damage the engine.

[ash_blore]

Originally Posted by k_nitin_r

The Maruti 800 can go at upto 130 kph and if you do have a long straight road, you just might be able to manage 140 kph. I'm sure that other hatchbacks such as the Maruti A-star can reach these speeds too.

As long as you have a 5-speed MT, it is safe to assume that your vehicle can handle speeds upto 120 kph on 5th gear without rpms high enough to damage the engine.

My assessment of A* is that its primarily a city car. Can be driven on the highway but its not built for that.
Also I would be skeptical of going above 90/100 kmph in a A*. Stability with stock tyres is a huge concern @ any speed beyond that.