[AYP]

So, Mahindra has launched a few petrols in the last few years which have peaked my interest-

1. XUV 7OO- 2.0 mStallion

Power and Torque figures- 200PS/380NM.

Power to torque ratio= 1.9

2. XUV 5OO- 2.2 petrol

Power and Torque figures- 140PS/320NM

Power to torque ratio= 2.29

I remember being absolutely baffled by the torque figure of the XUV 5OO petrol when it was launched back in 2018. And the launch of the XUV 7OO reminded me of the same.



Just for reference, this is what the power to torque ratio looks like for some other turbo petrols-

1. Jeep Compass 1.4 MultiAir-

Power and Torque figures- 163PS/250NM

Power to torque ratio= 1.53

2. VW T-ROC 1.5 TSI-

Power and Torque figures- 150PS/250NM

Power to torque ratio= 1.67

3. Skoda Octavia 2.0 TSI-

Power and Torque figures- 190PS/320NM

Power to torque ratio= 1.69

4. BMW M340i-

Power and Torque figures- 387PS/500NM

Power to torque ratio= 1.29


In fact as we keep approaching the supercar territory, this ration starts tending to 1.

5. Ferrari F8 Spider-

Power and Torque figures- 720PS/770NM

Power to torque ratio= 1.07



Let us know have a look at the power to torque ratio looks like for some turbo diesels-

1. VW Jetta(MK VI) 2.0 TDI-

Power and Torque figures- 140PS/320NM

Power to torque ratio= 2.29

2. Jeep Compass 2.0-

Power and Torque figures- 170PS/350NM

Power to torque ratio= 2.06

3. Hyundai Tucson 2.0-

Power and Torque figures- 185PS/400NM

Power to torque ratio= 2.16

4. Mahindra XUV 5OO 2.2 mHawk(2015)-

Power and Torque figures- 140PS/330NM

Power to torque ratio= 2.36

5. Mahindra XUV 7OO 2.2 mHawk MT-

Power and Torque figures- 185PS/420NM

Power to torque ratio= 2.27


There may be various reasons why this ratio starts to decrease as we approach high performance cars but for the consideration of this thread, let us consider the smaller turbo petrol engines varying from 1.4L to 2.2L displacement. As we all can see, Mahindra's turbo petrols have a power to torque ratio much closer to that of the turbo diesels than the turbo petrols. The torque generated by Mahindra's petrol is very diesel like.

My queries are-

1. Why is this the case? What are the technical and the commercial reasons which may have caused Mahindra to develop engines with such characteristic?

2. Why aren't the other manufacturers offering a similar high power to torque ratios in their offerings? And vice versa, why is Mahindra offering their engines with diesel like power to torque ratios?

3. What are the pros and cons of Mahindra's approach? Has Mahindra discovered an elixir which is enabling them to come up with such engines? Is there a catch?

4. Are there any other such examples of a company developing turbo petrol engines with diesel like torque?

You may have figured out that in spite of me stating my query by the means of 4 different questions, what I basically want to know is- 'Why? How? Others why not?'

[fhdowntheline]

Is it the case that the figures are specified "on crank" vs at the wheel and may result in different "real world" behavior?

[AYP]

My thoughts-

Since Mahindra is mainly a diesel engine oriented company, they have used the heavier blocks of their diesel engines to come up with a petrol, thus limiting their revving range but resulting in more torque.

Though again, the above is just a speculation from my end and I have nothing to back it up. Also, the other points like the pros and cons of this approach and why aren't the others doing it still eludes me.

[AMG Power]

Torque is a function of the power extracted from the engine. The higher the power output the lower the maximum torque (as a multiple) that you can extract from the engine. If you look at the swept volume to power output Mahindra’s ratio is very low, so the torque would be higher.

Skoda Kushaq - 1.5 ltr - 150 bhp

BMW 340i - 3.0 ltr- 387 bhp

Octavia - 2.0 ltr - 190 bhp

Jeep Compass - 1.4 ltr - 163 bhp

Mahindra - 2.2 ltr - 140 bhp

Mahindra have only extracted 140 bhp from a 2.2 litre engine. With the lower power output, they can extract more torque as a multiple of power output. If the same engine had a higher power output, the torque would be lower as a multiple of the power output - everything else remaining the same.

[anb]

Originally Posted by AMG Power

Torque is a function of the power extracted from the engine. The higher the power output the lower the maximum torque (as a multiple) that you can extract from the engine. If you look at the swept volume to power output Mahindra’s ratio is very low, so the torque would be higher. With the lower power output, they can extract more torque as a multiple of power output. If the same engine had a higher power output, the torque would be lower as a multiple of the power output - everything else remaining the same.

As per my basic understanding, Power, P = 2πNT/60. That is Power is equal to some constant multiplied by RPM and torque. So at constant RPM, power is directly proportional to torque. More the torque, more will be the power

[aargee]

Weight plays THE most important role; ideally measuring P2W gives a real world picture than anything else.

From my 2017 records when I was hunting for a car, sharing some stats below.



So, if you look at the chart, even though you look at some cars like Kodiaq, Fortuner & Crysta that has super high BHP or even Scorp & even XUV 500, they look good on paper, on road, it's entirely a different game (Scorp had 62.83 Bhp/tonne & XUV 500 had 78.43 Bhp/tonne). And for the other side, if you see cars like Aspire, they're below 100 Bhp, but they can easily give a run for money with SCross

[anb]

Originally Posted by AYP

So, Mahindra has launched a few petrols in the last few years which have peaked my interest-


2. XUV 5OO- 2.2 petrol

Power and Torque figures- 140PS/320NM

Power to torque ratio= 2.29

You may have figured out that in spite of me stating my query by the means of 4 different questions, what I basically want to know is- 'Why? How? Others why not?'

For XUV 5OO, the maximum RPM is only 4500 since it is based on long stroke heavy diesel engine block. The power is torque multiplied by RPM. Since the RPM is less, the power will be less for a high torque output.

For higher torque outputs of the m stallion engines, the explanation given by R Veluswamy, senior vice president of Mahindra is given below.

“Our diesel engines (mHawk) that power our SUVs are the best. We brought the same principle to petrol. But the way it works is different as diesel works with heavy torque and petrol works with high speed. We bought in TGDI technology to get the efficiency and torque to the Thar. When you have a turbocharged engine, there is no need for much engine speed as there is high torque and the gear ratios come down.”

“You can manage at 4,000rpm and you have to increase the stroke for efficiency and decrease the bore. This is where many petrol engine makers were caught out. We took a solid bet on the turbocharged engine, where our strokes (88mm) will be much longer than bores (76mm). We had a similar approach to the CRDE engine, where AVL is the partner for both,”

https://www.autocarindia.com/car-new...ol-suvs-420475

[GTO]

Mod Note: Thread moved to Tech Stuff. Thanks for sharing!

[nareshtrao]

Originally Posted by AYP

So, Mahindra has launched a few petrols in the last few years which have peaked my interest-

My queries are-

1. Why is this the case? What are the technical and the commercial reasons which may have caused Mahindra to develop engines with such characteristic?

2. Why aren't the other manufacturers offering a similar high power to torque ratios in their offerings? And vice versa, why is Mahindra offering their engines with diesel like power to torque ratios?

3. What are the pros and cons of Mahindra's approach? Has Mahindra discovered an elixir which is enabling them to come up with such engines? Is there a catch?

4. Are there any other such examples of a company developing turbo petrol engines with diesel like torque?

You may have figured out that in spite of me stating my query by the means of 4 different questions, what I basically want to know is- 'Why? How? Others why not?'

So while doing my research as a part of the buying process of comparing Thar Petrol vs. Diesel, I came across this thread. Also came across another article in Autocar from early 2020 which perhaps explains the answer to your question very well. Especially the choice of stroke and bore size and overall architecture to keep it more in behaviour like a diesel meant for SUVs and heavy vehicles.

Hence sharing.

This is a different article from the one shared earlier in the thread.

https://www.autocarindia.com/car-new...evealed-415926

[shankar.balan]

You may find some more info in this youtube video featuring Hormazd from Auto Car, talking about the Mahindra petrol engine.

https://youtu.be/UgLclu8OjOo

[starlord]

Originally Posted by AYP

My queries are-

1. Why is this the case? What are the technical and the commercial reasons which may have caused Mahindra to develop engines with such characteristic?

2. Why aren't the other manufacturers offering a similar high power to torque ratios in their offerings? And vice versa, why is Mahindra offering their engines with diesel like power to torque ratios?

3. What are the pros and cons of Mahindra's approach? Has Mahindra discovered an elixir which is enabling them to come up with such engines? Is there a catch?

1. Most likely due to taller cylinders which translate to higher torque and lower revving nature. This is more definitive.
Now my assumptions for why they did it are more guesswork. Mahindra did it probably out of experience, Indian road conditions do not warrant high rpm, high speed engine performance. Usually offroading demands are in the hills where higher torque is required at lower rpm to get out of sticky situations.

2. Other manufacturers are mostly japanese, they have a solid pedigree of flatter cylinders with high revving free flowing engines. They continue that legacy.

3. Pros - better low end grunt. Cons - Dunno.