Torque vs BHP?

sbasak · 16th August 2006, 14:34

Calculating torque/power by interpolation may not be accurate always.

Only the actual power-torque-curve can show the true torque/power at any RPM. The relationship is often not linear.

anToNIcHeN · 16th August 2006, 18:55

Quote:

Originally Posted by anToNIcHeN

Hi all,
I know this is a very old thread... But just to get my doubts clarified....

I heard a friend of mine saying that putting Petes performance kit on the car would increase its torque... how far is this true?...
how would Petes kit help in increasing the torque?....

Also how would you measure the torque? (what methodolgy is used?)

My friend also said that higher torque means... you can shift gears at lower speeds? is it true?

regards,
ant.

http://www.team-bhp.com/forum/164091-post39.html
This link says that, more fuel is burned to get more power... does it mean that torque is also increased?....
can i conclude that, when more fuel is burned within the given time, torque is also increased?...

Also, can you guys answer this query also?
1. how would you measure the torque? (what methodolgy is used?)
2. can you shift gears in lower RPMs when the torque is increased?

regards,
ant.

Shan2nu · 16th August 2006, 19:13

Quote:

This link says that, more fuel is burned to get more power... does it mean that torque is also increased?....
can i conclude that, when more fuel is burned within the given time, torque is also increased?...

Yes thats true. For that reason, all torque/power curves are calculated at full throttle (at any given rpm).

TC, SC and NOS work on the same principle. More air in the cylinder = more air fuel mixture = bigger explosion = more torque and power.

Shan2nu

Shan2nu · 16th August 2006, 19:19

Quote:

1. how would you measure the torque? (what methodolgy is used?)

For cars, they use dynos to calculate the torque curve and from this, the power curve is derived.

Quote:

2. can you shift gears in lower RPMs when the torque is increased?

As long as the vehicle speed allows for that gear to revv the engine at above the idling speed, it'l work. But this maynot be good for the engine. Always check the car manual for recomended shift points.

Shan2nu

SLK · 22nd August 2006, 04:35

Well, I've got nothing more to explain .... but I had made an excel file with graphs to depict torque and power curves of various cars ... but in the absence of detailed information its just a play-around thing. BUT it surely helps you understand how things work between power and torque.

I have a few cars input there.... plz don't ask me how I filled in the data as I can't explain it. Study the sheet hard enough you will know.

Cars input: Santro erlx, zen, wagonR, City ZX, City ZX Vtec, Baleno

if you see the pic below you can download the sheet else you can't..

PS: the data might just be far from even an estimate.

alexrabbi · 22nd August 2006, 18:10

Hi anToNIcHeN

Torque is measured this way

Torque = (Horse power * 5252) / RPM

and Horse power is measured this way

Horse Power = (Torque X RPM) / 5252

Bye
Alex

jat · 23rd August 2006, 21:42

Check this link on the team-bhp

devsus · 1st October 2006, 20:02

hello bhpian's,
one technical question :-> suppose there are two vehicle's A & B , both having similar specification ( engine ( V4-4valve), layout, wheelbase.., engine capacity etc..etc..) but different BHP@RPM..........."A" having 250 BHP @ 7000 RPM while "B" having 250 BHP @ 10,500 RPM...........now u have to tell from both of the vehicles which one is better and why?

nitrous · 1st October 2006, 20:09

Well, when it comes to road use, its better to have the peak power earlier.
And when it comes to racing, its better to have the peak power later.

ess_a · 1st October 2006, 20:37

Quote:

Originally Posted by nitrous

Well, when it comes to road use, its better to have the peak power earlier.
And when it comes to racing, its better to have the peak power later.

Why should the peak power come later?

danlalan · 1st October 2006, 20:47

well for top speed or for high end power...10,500 is good....

devsus · 1st October 2006, 21:01

Quote:

Originally Posted by danlalan

well for top speed or for high end power...10,500 is good....

well, u r very right that's why in formula 1/motogp...... RPM level goes to 20,000RPM/16,000RPM..............

GTO · 1st October 2006, 22:10

Quote:

A" having 250 BHP @ 7000 RPM while "B" having 250 BHP @ 10,500 RPM...........

Generally and with all things being equal...the 2nd engine will be smaller in size than the 1st engine. Thats how it is able to meet 250BHP at 10,500 rpm while the 1st makes the same amount of power at a much lesser RPM.

Weight is an important consideration in racing, and there are several rule restrictions. Thats why we see high-revving 3000cc (now 2400cc) Formula 1 engines producing 800 bhp but at 17000 - 18000 rpm. Compare that to an Accords 3000cc engine which makes about 30% of the power. But then, Formula1 engines are not built to last 2,00,000 kms and meet emission requirements.

Some stock engines converted to race use have their revv limit increased only to avoid unsettling the car in a corner. The last thing you want in a challenging corner is to upshift and upset the balance.

It all depends on the application and is difficult to say which of the two will be better. Buttttttttttttttttttttttt more RPM does not necessarily mean more power. Yet it certainly means more wear and tear.

ess_a · 1st October 2006, 22:45

Quote:

Originally Posted by nitrous

Well, when it comes to road use, its better to have the peak power earlier.
And when it comes to racing, its better to have the peak power later.

Why should the peak power come later?

But my question remains... why is it better for the peak power to come late? If the same power can be obtained at lower rpms, wont the car accelerate faster?
One thing can be the size of the engine (as GTO pointed out that weight is a factor) and smaller engines ( those used for racing) need muuuch higher rpms to deliver the same out put..
But then nitrous is pointing out to something different....
Please someone clarify...

Pankaj401 · 1st October 2006, 23:15

If you get the peak power later in the rev band you can achieve greater top speed becuase that's where the greater power is needed to counter the aerodynamic drag force.

16th August 2006, 14:34	#46
sbasak BHPian Join Date: Nov 2005 Location: CCU-LTN Posts: 608 Thanked: 14 Times	Calculating torque/power by interpolation may not be accurate always. Only the actual power-torque-curve can show the true torque/power at any RPM. The relationship is often not linear.
	(1) Thanks

22nd August 2006, 04:35	#50
SLK Senior - BHPian Join Date: Feb 2004 Location: DL XX XX XXXX Posts: 1,634 Thanked: 1,011 Times	Well, I've got nothing more to explain .... but I had made an excel file with graphs to depict torque and power curves of various cars ... but in the absence of detailed information its just a play-around thing. BUT it surely helps you understand how things work between power and torque. I have a few cars input there.... plz don't ask me how I filled in the data as I can't explain it. Study the sheet hard enough you will know. Cars input: Santro erlx, zen, wagonR, City ZX, City ZX Vtec, Baleno if you see the pic below you can download the sheet else you can't.. PS: the data might just be far from even an estimate.
	() Thanks

22nd August 2006, 18:10	#51
alexrabbi BANNED Join Date: May 2006 Location: Bangalore Posts: 131 Thanked: 21 Times	Hi anToNIcHeN Torque is measured this way Torque = (Horse power * 5252) / RPM and Horse power is measured this way Horse Power = (Torque X RPM) / 5252 Bye Alex
	() Thanks

23rd August 2006, 21:42	#52
jat BHPian Join Date: Dec 2005 Location: SINGAPORE Posts: 265 Thanked: 7 Times	Check this link on the team-bhp
	() Thanks

1st October 2006, 20:02	#53
devsus BHPian Join Date: Apr 2006 Location: ajmer Posts: 70 Thanked: 0 Times	BHP@RPM Mystery hello bhpian's, one technical question :-> suppose there are two vehicle's A & B , both having similar specification ( engine ( V4-4valve), layout, wheelbase.., engine capacity etc..etc..) but different BHP@RPM..........."A" having 250 BHP @ 7000 RPM while "B" having 250 BHP @ 10,500 RPM...........now u have to tell from both of the vehicles which one is better and why?
	() Thanks

1st October 2006, 20:09	#54
nitrous Senior - BHPian Join Date: May 2004 Location: UAE/Lon/Madras Posts: 6,965 Thanked: 325 Times View My Garage	Well, when it comes to road use, its better to have the peak power earlier. And when it comes to racing, its better to have the peak power later.
	(1) Thanks

1st October 2006, 20:47	#56
danlalan Senior - BHPian Join Date: Nov 2005 Location: mumbai,JUHU Posts: 1,636 Thanked: 263 Times View My Garage	well for top speed or for high end power...10,500 is good....
	() Thanks

1st October 2006, 23:15	#60
Pankaj401 BHPian Join Date: Mar 2006 Location: Bangalore, India Posts: 215 Thanked: 6 Times	If you get the peak power later in the rev band you can achieve greater top speed becuase that's where the greater power is needed to counter the aerodynamic drag force.
	() Thanks