Relationship between CC and BHP

shuvc · 27th January 2006, 11:14

This is something that intrigues and confuses me, maybe 'coz

Some engines produce loads of BHP with smaller CC, whereas others don't with larger displacement. And I am not talking of turbo'ed cars.

Say OHC 1.3 produces 90bhp, Indica 1.4 produces 70 BHP (Xeta), Baleno 1.6 --> 94 ... Corolla 1.8 --> 125, but cedia 2.0 --> 115 ...

Example:
Why does Mitsu need to launch a 2.0 engine to just produce 115 BHP ? Couldn't they have done it with a 1.8 (they already do with the Invex).

What is the advantage of having a higher BHP from lower CC and vice versa ?
Does higher BHP from low CC translate to better performance at low cost ?
Does lower BHP from high CC translate to better FE ?

tifosikrishna · 27th January 2006, 11:34

From my little understanding, lower bhp from higher cc means, better FE, and the engine is not stretched (detuned), so better engine life and inturn, running at lower rpm means better NVH and comfort.

sbasak · 27th January 2006, 14:49

CC is related with torque directly. Higher CC means more torque. And faster the engine revs, more BHP is rated for it. Since diesel engines have lower RPM, their BHP rating is low, yet because of high CC, their torque is usually higher.

See the How to increase torque in engine? section in this post
http://www.team-bhp.com/forum/techni...-movement.html

goldie_malhotra · 27th January 2006, 15:00

Not too much of technical insight, but from a lay-mans perspective ---

Performance and FE are not only determined by BHP and CC, but by other factors like

1. weight of the car - lighter the car, lesser torque required to propel it forward
2. transmission efficiency - how much power produced by the engine is actually being delivered to the wheels
3. gearing - how is the power getting translated.
4. traction control - are the wheels able to gain enough traction to use the torque delivered.
5. engine technology - variable iginition, valve, cylinder, timing etc... how efficiently is the fuel burnt, is it burnt when required ...
6. aerodynamics - is the wind cutting down on the momentum.

It seems like a very complex equation based upon above (& other) factors. Car designers have to grapple with all of the above to come up with the right amount of CC and BHP depending on the needs of the car.

BUSA · 27th January 2006, 18:34

Quote:

Say OHC 1.3 produces 90bhp, Indica 1.4 produces 70 BHP (Xeta), Baleno 1.6 --> 94 ... Corolla 1.8 --> 125, but cedia 2.0 --> 115 ...

All this depends on the tuning of the car, gear ratios. Some Manufacturers(or rather most of them) detune cars for FE and Fuel quality. More CC engine More BHP( to a certain limit) More BHP (Better Pick up) More CC less FE and vice versa

tifosikrishna · 27th January 2006, 18:39

Quote:

Originally Posted by BUSA

All this depends on the tuning of the car, gear ratios.

Can gear ratio affect the BHP of the engine? i really dont know, could you please throw some light.

Deeps · 27th January 2006, 21:41

No, because the engine produces the same bhp at a given rpm at any gear. But the ratios do affect the torque.

shuvc · 30th January 2006, 13:16

Quote:

Originally Posted by Deeps

No, because the engine produces the same bhp at a given rpm at any gear.

FE should depend on rpm, right ? If so, will I get the same FE, if I say drive the same Xkms stretch at 1500rpm only in 1st gear or only in 2nd gear or 3rd etc .. ?

jat · 30th January 2006, 15:42

Higher gear and lower rpm (but not the lowest) gives you better fuel economy. More than that the constant speed gives a better fuel economy.

RK

Deeps · 30th January 2006, 15:58

Quote:

Originally Posted by jat

Higher gear and lower rpm (but not the lowest) gives you better fuel economy. More than that the constant speed gives a better fuel economy.

RK

To elaborate on that a little bit, you'd be doing higher speeds ina higher gear at 1500 rpm. So the best thing to do would be to use 5th at 1500 rpm. you'd also get to your destination faster.

shuvc · 30th January 2006, 20:06

Then again, even from the same manufacturer ..
Honda produced 90 bhp from 1.3L and only 10 more horses from the 1.5 L engine ? Beats me ....

SRK · 30th January 2006, 20:17

I think cc is directly related to mass of vehicle.
i.e more the more mass ,more cc is required ,to produce more bhp.
Eg:- in bigger engines like the ones in truck ,they are big cc but produce less bhp.
Less cc in bikes but more bhp.
These bhp and cc thing is inter-related and only a true expert can explain it.
I just gave my opinion, I dont have any technical knowledge,I may be wrong!

jat · 31st January 2006, 01:20

To understand the relation between CC and BHP, we have to keep other factors constant.

CC and BHP is directly related, that is increase in CC increases the BHP. For example you have an engine with two cylinders with certain BHP. If you add two more cylinders then BHP is doubled.

Your confusion comes from other factors. Because BHP can be increased without increasing the CC by many other factors.

1. Letting the engine breath more freely by having more valve, increasing lift etc. It allows more air and hence more power. (VTEC, VVTi etc)
2. Turbocharging or supercharging - again supplying more air and hence more power. CC does not change again.
3. Increasing the rpm. As power is product of torque and rpm, you can make the engine high revving and hance more power (prime example - OHC VTEC)
etc. etc. etc

Therfore just comparing CC and BHP is not directly possible.

Just see the link and where the engine produces just above 4 bhp/litre compared to around 65~70 bhp/lt for car engines.

http://www.team-bhp.com/forum/techni...ghlight=diesel

RK

Beeman · 31st January 2006, 16:50

As far as i know CC or cubic capacity is the difference between the maximum and minimum movement of the piston in a cylinder. The greater the cylinders in a car the more the CC, also depending on the size of each cylinder also affect the CC. More the cc greater the bhp as well.
Basically the capacity in the cyclinder's is measured in terms of Litre's as well. That is why we could call a car having a 2.0 Litre engine or 2000cc engine (they both mean the same thing)
There are many other factors like some mentioned above which is the power-weight ratio which also have an impact on the car.

sumitsingh · 29th March 2006, 16:41

Can the experts please correlate the following assuming other things are kept constant.

a) cubic capacity
b) BHP
c) Torque

I am asking this question because as a person evaluating certain options, I seem to be asking this question to myself. The Ford Fiesta 1.4 produces a torque of about 12.9 Kgm with 82 horses with a DOHC engine. The Chevrolet Aveo 1.4 produces a torque of about 12.7 Kgm with 94 horses with a DOHC engine.

What would be the impact of this in the real world driving.

Thanks
-Sumit

27th January 2006, 11:14	#1
shuvc Senior - BHPian Join Date: May 2005 Location: Kolkata Posts: 2,913 Thanked: 352 Times View My Garage	Relationship between CC and BHP This is something that intrigues and confuses me, maybe 'coz Some engines produce loads of BHP with smaller CC, whereas others don't with larger displacement. And I am not talking of turbo'ed cars. Say OHC 1.3 produces 90bhp, Indica 1.4 produces 70 BHP (Xeta), Baleno 1.6 --> 94 ... Corolla 1.8 --> 125, but cedia 2.0 --> 115 ... Example: Why does Mitsu need to launch a 2.0 engine to just produce 115 BHP ? Couldn't they have done it with a 1.8 (they already do with the Invex). What is the advantage of having a higher BHP from lower CC and vice versa ? Does higher BHP from low CC translate to better performance at low cost ? Does lower BHP from high CC translate to better FE ?
	() Thanks

27th January 2006, 11:34	#2
tifosikrishna BHPian Join Date: Oct 2005 Location: chennai Posts: 827 Thanked: 383 Times View My Garage	From my little understanding, lower bhp from higher cc means, better FE, and the engine is not stretched (detuned), so better engine life and inturn, running at lower rpm means better NVH and comfort.
	() Thanks

27th January 2006, 14:49	#3
sbasak BHPian Join Date: Nov 2005 Location: CCU-LTN Posts: 608 Thanked: 14 Times	CC is related with torque directly. Higher CC means more torque. And faster the engine revs, more BHP is rated for it. Since diesel engines have lower RPM, their BHP rating is low, yet because of high CC, their torque is usually higher. See the How to increase torque in engine? section in this post http://www.team-bhp.com/forum/techni...-movement.html Last edited by sbasak : 27th January 2006 at 14:50.
	() Thanks

27th January 2006, 15:00	#4
goldie_malhotra BHPian Join Date: Nov 2005 Location: New Delhi Posts: 757 Thanked: 12 Times	Not too much of technical insight, but from a lay-mans perspective --- Performance and FE are not only determined by BHP and CC, but by other factors like 1. weight of the car - lighter the car, lesser torque required to propel it forward 2. transmission efficiency - how much power produced by the engine is actually being delivered to the wheels 3. gearing - how is the power getting translated. 4. traction control - are the wheels able to gain enough traction to use the torque delivered. 5. engine technology - variable iginition, valve, cylinder, timing etc... how efficiently is the fuel burnt, is it burnt when required ... 6. aerodynamics - is the wind cutting down on the momentum. It seems like a very complex equation based upon above (& other) factors. Car designers have to grapple with all of the above to come up with the right amount of CC and BHP depending on the needs of the car.
	() Thanks

27th January 2006, 21:41	#7
Deeps Senior - BHPian Join Date: May 2004 Location: Delhi/Noida Posts: 1,116 Thanked: 170 Times	No, because the engine produces the same bhp at a given rpm at any gear. But the ratios do affect the torque.
	() Thanks

30th January 2006, 15:42	#9
jat BHPian Join Date: Dec 2005 Location: SINGAPORE Posts: 265 Thanked: 7 Times	Higher gear and lower rpm (but not the lowest) gives you better fuel economy. More than that the constant speed gives a better fuel economy. RK
	() Thanks

30th January 2006, 20:06	#11
shuvc Senior - BHPian Join Date: May 2005 Location: Kolkata Posts: 2,913 Thanked: 352 Times View My Garage	Then again, even from the same manufacturer .. Honda produced 90 bhp from 1.3L and only 10 more horses from the 1.5 L engine ? Beats me ....
	() Thanks

30th January 2006, 20:17	#12
SRK Senior - BHPian Join Date: Sep 2005 Location: Mumbai Posts: 1,201 Thanked: 524 Times	I think cc is directly related to mass of vehicle. i.e more the more mass ,more cc is required ,to produce more bhp. Eg:- in bigger engines like the ones in truck ,they are big cc but produce less bhp. Less cc in bikes but more bhp. These bhp and cc thing is inter-related and only a true expert can explain it. I just gave my opinion, I dont have any technical knowledge,I may be wrong!
	() Thanks

31st January 2006, 01:20	#13
jat BHPian Join Date: Dec 2005 Location: SINGAPORE Posts: 265 Thanked: 7 Times	To understand the relation between CC and BHP, we have to keep other factors constant. CC and BHP is directly related, that is increase in CC increases the BHP. For example you have an engine with two cylinders with certain BHP. If you add two more cylinders then BHP is doubled. Your confusion comes from other factors. Because BHP can be increased without increasing the CC by many other factors. 1. Letting the engine breath more freely by having more valve, increasing lift etc. It allows more air and hence more power. (VTEC, VVTi etc) 2. Turbocharging or supercharging - again supplying more air and hence more power. CC does not change again. 3. Increasing the rpm. As power is product of torque and rpm, you can make the engine high revving and hance more power (prime example - OHC VTEC) etc. etc. etc Therfore just comparing CC and BHP is not directly possible. Just see the link and where the engine produces just above 4 bhp/litre compared to around 65~70 bhp/lt for car engines. http://www.team-bhp.com/forum/techni...ghlight=diesel RK Last edited by jat : 31st January 2006 at 01:25.
	(1) Thanks

31st January 2006, 16:50	#14
Beeman BHPian Join Date: Dec 2005 Location: Treasure island Posts: 335 Thanked: 2 Times	As far as i know CC or cubic capacity is the difference between the maximum and minimum movement of the piston in a cylinder. The greater the cylinders in a car the more the CC, also depending on the size of each cylinder also affect the CC. More the cc greater the bhp as well. Basically the capacity in the cyclinder's is measured in terms of Litre's as well. That is why we could call a car having a 2.0 Litre engine or 2000cc engine (they both mean the same thing) There are many other factors like some mentioned above which is the power-weight ratio which also have an impact on the car.
	() Thanks

29th March 2006, 16:41	#15
sumitsingh BHPian Join Date: Sep 2005 Location: Noida Posts: 128 Thanked: 0 Times View My Garage	Can the experts please correlate the following assuming other things are kept constant. a) cubic capacity b) BHP c) Torque I am asking this question because as a person evaluating certain options, I seem to be asking this question to myself. The Ford Fiesta 1.4 produces a torque of about 12.9 Kgm with 82 horses with a DOHC engine. The Chevrolet Aveo 1.4 produces a torque of about 12.7 Kgm with 94 horses with a DOHC engine. What would be the impact of this in the real world driving. Thanks -Sumit
	() Thanks