How To Read Engine Specifications?

[RSM]

Guys,
This might seems basic question, but till now i am not very much clear what to make out of engine specifications like -
Power (PS@rpm) 76@4000
Torque ( Nm@rpm) 197@1750
Are these specifies max. power or torque?

 

[Crazy cat]

This means that max power of 76PS is attained at 4000 RPM. The same for torque too. More torque available at lesser RPM helps in better driveability.

 

[RSM]

This means that max power of 76PS is attained at 4000 RPM. The same for torque too. More torque available at lesser RPM helps in better driveability.

So it means Torque at low RPM is more useful for city driving and more Power will be good for Highway driving? Am i correct to understand this?

 

[racerdabba]

Yes you are.
More torque at low rpms are great for city, which means lesser gear shifting, and more accelaration at the lights. More power neccesarily helps for top speed stints on highways. but overtaking needs torque on demand.
To make it simple,
Torque-Accelaration
Power- Top speed

 

[Neil.Bhujbal]

These seem to be you cars performance specifications.

1) 76 Ps @ 4000 RPM - It means all the horses(power) of your vehicle is max at 4000 RPM.
" This Power " will drop if you shift gears above 4000 RPM. So next time you go for a race make sure you shift your gears right at 4000 Rpm.

2) 197 Nm @ 1750 RPM - Torque we call it.Torque in short is the twisting force or the force that produces rotary motion or rotational force. It is max at 1750 RPM for your car.

Like CC said,"More torque available at lesser RPM helps in better driveability."

This means you don't have to constantly downshift in traffics for the car to pull because you have the max torque(the twisting force) available at 1750 RPM itself.

Where as for higher speeds the torque ain't needed much as the car is already in motion (the twisting force is not needed much).

 

[Arun]

Yes you are.
More torque at low rpms are great for city, which means lesser gear shifting, and more accelaration at the lights. More power neccesarily helps for top speed stints on highways. but overtaking needs torque on demand.
To make it simple,
Torque-Accelaration
Power- Top speed

+1

Well explained Sirjee!
Cars like the WagonR and the Estilo have a flat torque curve. They are zippy around the city. Quick to accelerate out of a deficit or a halt. The same thing will feel sluggish on a highway.

 

[RSM]

These seem to be you cars performance specifications.

1) 76 Ps @ 4000 RPM - It means all the horses(power) of your vehicle is max at 4000 RPM.
" This Power " will drop if you shift gears above 4000 RPM. So next time you go for a race make sure you shift your gears right at 4000 Rpm.

2) 197 Nm @ 1750 RPM - Torque we call it.Torque in short is the twisting force or the force that produces rotary motion or rotational force. It is max at 1750 RPM for your car.

Like CC said,"More torque available at lesser RPM helps in better driveability."

This means you don't have to constantly downshift in traffics for the car to pull because you have the max torque(the twisting force) available at 1750 RPM itself.

Where as for higher speeds the torque ain't needed much as the car is already in motion (the twisting force is not needed much).

Thanks, great information. It clears my all doubts.
Yes the specification you mentioned is for my Punto.

 

[RSM]

Normally i see diesel engines have more torque than petrol engines and power is more in Petrol than diesel, so which is better for city driving?

Cars like the WagonR and the Estilo have a flat torque curve.

What this curve all about?

 

[ilango[speed thirst]]

curves are the graphical representation for each rpm.

the one u posted will be in peak of the graph.


If diesel engine have same torque design , then it will be worse sluggish car.

Torque is designed according to the weight of the car too. so naturally for diesel you need more than a peppy petrol car.


And in your car , you'll get max power only at 4000 rpm , which you don't normally drive.

 

[Aditya]

The main reason max power defines top speed is that the major "deterrent" at high speeds is the wind resistance. As such, you need more power to "punch" a hole thru the air to travel faster.

 

[cooldhaya]

Hey guys now i want to understand and compare the torque figures of a petrol and diesel engine of some cars belonging to the same segment! Say for eg Verna CRDI vs Honda City or any other comparison like this!

I want to understand why petrol engines have superior pick-up when compared to diesels with the torque figures!

Can somebody help me out??

 

[racerdabba]

There are thousands out there to help you dhaya..
In the meantime, i'll try..
Diesels have a rev range almost half of that of petrol engines. For example, the safari dicor redlines at 4500, when even a maruti 800 does 8000....
This needs that taller gears rae used in diesels to compensate for their redlines. Their torque further helps the tall gearing, which also improves fuel efficiency.
So, to get to 100kmph on a diesel, u'll make it in just 2nd, but for the same sprint, u'll need 3rd on a petrol.
The taller gears on diesel make it a slow accelarator, but it also means high top ends, and less gear shifting.

 

[ilango[speed thirst]]

Exact .

higher gear ratios have high top end , but low acceleration .

That is the reason for 1st gear present in the car . It gives out more acceleration at low rpm / torque



impractical way - have different set of gear box to match the mood
-----------Next Post-----------
The same thing which we can experience in 2 wheelers. geared cycle

Eg in bike at rear sprocket a teeth less makes acceleration but lose top end , and vice versa.

 

[cooldhaya]

OH now i get it , thanks for the explanation Racerdabba! So diesels can outperform petrols in the highways or in a drag race ( cars belonging to the same segment only)??

 

[RSM]

I was just comparing the Figo's and Punto's engine specification.

I know(read) Figo's engine is more powerful, but i want to know how can you make out after seeing the specs?