[ryder]

I've browsed through 4 pages of threads here and cannot find a topic that covers this and would appreciate if someone can provide a general answer to my query.

Until today I still do not know what does the maximum power output and maximum torque as indicated in specifications of vehicles tell us generally. I have read that the torque curve is more important, but there must be something about the figures of the max. power and torque that most car manufacturers publish these data. What do we normally look in these pulished datas? Which one is the more important figure, the output or the torque?

For example, a vehicle has a maximum output of 180PS/6,500rpm and maximum torque of 222Nm/4,300rpm. When comparing against another vehicle, which figure do we take? Is PS the short form of power supply, and is it the same as hp or bhp?

Any advice would be most appreciated.

[vr2turbo]

I've browsed through 4 pages of threads here and cannot find a topic that covers this and would appreciate if someone can provide a general answer to my query.

Until today I still do not know what does the maximum power output and maximum torque as indicated in specifications of vehicles tell us generally. I have read that the torque curve is more important, but there must be something about the figures of the max. power and torque that most car manufacturers publish these data. What do we normally look in these pulished datas? Which one is the more important figure, the output or the torque?

For example, a vehicle has a maximum output of 180PS/6,500rpm and maximum torque of 222Nm/4,300rpm. When comparing against another vehicle, which figure do we take? Is PS the short form of power supply, and is it the same as hp or bhp?

Any advice would be most appreciated.

PS is (German: Pferdestärke = horse strength)

Both figures are equally important. One tell you the maximum power of the engine. The other the maximum pulling/working strength.
A car with high torque has better pulling power. You will feel they are easier to drive, pulls faster, overtake better too.
Some torque max at higher rpm and some at lower rpm as in diesel engine. That is why diesel engine are use mostly for trucks, buses.

Am not good in explanation. Hope you understand the brief write up above....

rdgs,

[alldisc]

vr2turbo had explain some and allow me to add.

the more horsepower we get from a car (measured either in PS-DIN, hp, bhp or kW) or the more torque is the better lah.

the problem is

1. for en engine with a certain power output, is it good enough??
example a Proton Wira with 1.5 12V EFI engine can churned out around 90bhp, but a Vios 1.5 EFI DOHC with VVTI can produce 109bhp. the latest honda city 1.5 IVTEC pushes the ceiling even higher at 120hp.

the lesser horsepower effects on acceleration top speed.

use the figures as comparisons between different cars.

2. for torque (measured in either N/m or lb/ft) is how high the output per rpm. if peak torque reaches only during high rpm then the engine is useless in a way. the driver need to change gear often to be in the most optimum speed range.

on the other hand, it is the better if the torque curve is as flat as possible. one will need a graph showing this to understand. if the torque curve is unknown, one can always do a dyno test and then get a print out.

diesel engine produces fatter torque than petrol engines of the same capacity. and normally a long stroke engine (undersquare) often has better low end torque compare to short stroke (oversquare) engines.

same goes to SOHC (better low end torque) and DOHC (higher output and higher torque but at a higher rpm).

this may get to technical so i better stop here.

[kohf1drive]

vr2turbo had explain some and allow me to add.

the more horsepower we get from a car (measured either in PS-DIN, hp, bhp or kW) or the more torque is the better lah.

the problem is

1. for en engine with a certain power output, is it good enough??
example a Proton Wira with 1.5 12V EFI engine can churned out around 90bhp, but a Vios 1.5 EFI DOHC with VVTI can produce 109bhp. the latest honda city 1.5 IVTEC pushes the ceiling even higher at 120hp.

the lesser horsepower effects on acceleration top speed.

use the figures as comparisons between different cars.

2. for torque (measured in either N/m or lb/ft) is how high the output per rpm. if peak torque reaches only during high rpm then the engine is useless in a way. the driver need to change gear often to be in the most optimum speed range.

on the other hand, it is the better if the torque curve is as flat as possible. one will need a graph showing this to understand. if the torque curve is unknown, one can always do a dyno test and then get a print out.

diesel engine produces fatter torque than petrol engines of the same capacity. and normally a long stroke engine (undersquare) often has better low end torque compare to short stroke (oversquare) engines.

same goes to SOHC (better low end torque) and DOHC (higher output and higher torque but at a higher rpm).

this may get to technical so i better stop here.

Bro keep going, i'm very exited to know more
In term of hp/l. The higher mean more efficient n better fuel economy or to certain extent like
> 100hp/l will consume more fuel?

[alldisc]

Bro keep going, i'm very exited to know more
In term of hp/l. The higher mean more efficient n better fuel economy or to certain extent like
> 100hp/l will consume more fuel?

not necessarily.

specific power output like u mentioned is only used to set as a benchmark.

by the 80s, only 2 companies can get 100bhp per litre mark.

1. BMW, if i am not mistaken their coupe M1 (launched in 70s i think), or M3 or M5. need to ask BMW expertise.

2. the other one is Daihatsu, though with the aid of turbocharger in Charade GTti. the 1.0 12V DOHC engine produces about 100bhp from its 993cc engine.

later in 90s, McLaren managed to engineer their F1 model to produce about 620bhp from 6.1 litre engine.

and the most recent is Honda. their soft top S2000 has about 240bhp from 2000cc, normally aspirated engine.

specific power output does little to affect fuel consumption.

by physics law FC depends on engine capacity the bigger the displacement the higher the FC as well as engine speed. the higher its rpm, the more it consumes fuel.

only in this last decade that technologies came into play with FC.
EFI, turbo/supercharger, and variable valve timing all played important roles in order to produce more output but using less fuel.

[ryder]

Thanks for all responses. They were useful and most appreciated.

I have done some homework compiling all maximum power output and torque figures of most popular Japanese vehicles during the weekend when I browsed through the specification sheets on the respective webpage. I will tabulate them out within these few days.

By the way, the maximum power output indicated in the specifications is in PS. Is the correct term for this PS hp or bhp? For instance, maximum power output indicated in the specification is 180PS/6,500rpm. Is it 180hp/6,500rpm or 180bhp/6,500rpm?

[alldisc]

hp is the amount of horsepower produced by an engine and measured at the crankshaft

bhp is the amount of horsepower produced by the engine but measured at the wheels (or the brakes, hence brake horse power)

PS is a different standard of measurement.

for one same engine, the figures may not be necessarily same.

[vr2turbo]

Bro keep going, i'm very exited to know more
In term of hp/l. The higher mean more efficient n better fuel economy or to certain extent like
> 100hp/l will consume more fuel?

Power does not means it is fuel efficient. But with better torque, FC can be better.
As explained by alldisc, the flatter the torque curve the more efficient the engine, therefore you uses less gear change to reach your optimum speed, then FC could be better.

rdgs,

[bOROi]

Power does not means it is fuel efficient. But with better torque, FC can be better.
As explained by alldisc, the flatter the torque curve the more efficient the engine, therefore you uses less gear change to reach your optimum speed, then FC could be better.

rdgs,

okay sifus, with regard to torque, sometime max torque is quoted at say 240NM at 5,000rpm and the max rpm before cutoff is 6,000rpm and yet the torque at that point is lower, theres curve in the torque peaking at 5,000rpm. Now if max torque is achieved at 5,000rpm why would the manufacturer put the cutoff at 6,000rpm, wouldn't it better to just have the cutoff at 5,000rpm when the torque is at the maximum.


Regards

[vr2turbo]

okay sifus, with regard to torque, sometime max torque is quoted at say 240NM at 5,000rpm and the max rpm before cutoff is 6,000rpm and yet the torque at that point is lower, theres curve in the torque peaking at 5,000rpm. Now if max torque is achieved at 5,000rpm why would the manufacturer put the cutoff at 6,000rpm, wouldn't it better to just have the cutoff at 5,000rpm when the torque is at the maximum.


Regards

But some torque peaks at a lower RPM than that, say 4k RPM. Do you want the engine to cut at 4k RPM?
Why they cut at max power is because that is the engine max output. Even though the engine torque have been reach at a lower RPM, the higher RPM at max power still contribute to higher end speed.

Changing gear at max output will see you going faster as during gear change the rev will fall into the torque RPM range.

rdgs,