What's new

Torque?

S

SX2002

Guest
Is there any way of calculating torque from the power output...even a ball park figure?
E.G. If my motor output is 175kW, can I calculate an approx. torque figure?
The stock output is 147kW and the torque is 269Nm...with exhaust and induction mods the power is now 175kW......the torque....????
 
G

gunner93

Guest
SX2002,

Thats approx 234 bhp or 328Nm ball park...
What the boost and mod on the SR?
 
P

Paddy

Guest
One is supposed to be directly linked to the other, I believe. Not sure of how its calculated though.
found it in my college notes!
Brake Power[kW] = (2(pi)(rpm)(torque[nm]))/60

Double dutch! :wack::thumbs:
 
S

SX2002

Guest
Stock147kW (motor) + 13kW induction mods (ATW) + 8Kw Exhaust (ATW)
The induction and exhaust (ATW) figures are obviously higher at the motor output. Just adding the 147 + 13 + 8 = 168KW (motor) I've added another 7kW even though it would in actual fact be higher due to the fact there is a percentage loss through the drive train.......anyone got an engine dyno in their pocket?
The turbo is stock 0.7 BAR (?)
 
P

Paddy

Guest
:confused::confused::confused::confused::confused: ah... eh...
was kinda hoping that someone wouldn't ask me that!!
lemme put my thinkin cap on :wack: and remember back to the good ol days :hurl:

torque and power are related at a given rpm, however, peak torque and max hp aren't directly related. that cos peak torque can be at 4k rpm while max power is nearer to 6k
i could prob find out what torque its making at max power output but it will actually be less than max eng torque... if i knew the rpms that is

also, how do you know what kws your mods are making?? and if they are rated at the wheel powers, they should be a good bit higher at the fly... maybe even 25-35% more...

i just don't see where the extra 7kWs you added is coming from? some other mod?


Phew :yawn:
 
S

SX2002

Guest
Hi Paddy,
The extra 7kW is a rough estimation of the 25 - 30% loss through the drive train.
Doing the sums allowing for the 20 - 30% we get....
the 13kW = 16.25kW - 16.9Kw
the 8kW = 10kW - 10.4kW
Added together we get 26.25 - 27.3kW
Add this to the 147kW....173.25 - 174.3kW
So, my estimation was really pretty spot on as it turns out.
I understand what you are saying about the torque, if my memory serves me well without delving in to my files, the max torque comes on at 4800rpm and the max power at 6400rpm, in the standard motor, so a calculation would be hard.
Oh, and the power from the induction mods were dyno proven and the exhaust was a verbal from D&T Performance Exhausts here in Australia...they had done heaps of S15s and assured me this was what previous dyno runs had shown. It also saved me $129 to do again what they had already proven.
Just out of interest, the figures my car showed on the dyno were even better than the 20% loss. It showed 120kW (18.5% loss) without the induction mods and 133kW with. This figure, 120kW, is pretty well exactly what a lot of other dyno runs I have read about show. One I have the article on shows a stock S15 with 126.7kW ATW
Cheers,
Ron.
 
Last edited:
P

Paddy

Guest
Cool, interesting to know what the transmission efficiency is. i havent really considered dynoing my car til i do some crazy engine mods eg ecu
I just could justify spending money on a dyno for each and every mod imaginable

The maths involved would be a right PITA. but it would be "fairly easy" - gonna regret saying that:wack: - to find power at max torque and torque at max power

but to really see how the mods have effected the torque, you'd need a dyno and to look at the torque curve. you can gain loads of kWs but the peak torque might be the same, you'd just be getting more NMs at different points as you rev it... net result being more kWs

Or a least thats my understanding of it
Paddy
 
Top