Go Back   Team-BHP > Under the Hood > Technical Stuff


Reply
 
LinkBack Thread Tools Search this Thread
Old 27th January 2006, 11:14   #1
Senior - BHPian
 
shuvc's Avatar
 
Join Date: May 2005
Location: Kolkata
Posts: 2,834
Thanked: 240 Times
Default 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 ?
shuvc is online now   Reply With Quote

Old 27th January 2006, 11:34   #2
BHPian
 
Join Date: Oct 2005
Location: chennai
Posts: 636
Thanked: 32 Times
Default

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.
tifosikrishna is offline   Reply With Quote
Old 27th January 2006, 14:49   #3
BHPian
 
sbasak's Avatar
 
Join Date: Nov 2005
Location: CCU-LTN
Posts: 606
Thanked: 5 Times
Default

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 (Physics behind car's movement)

Last edited by sbasak : 27th January 2006 at 14:50.
sbasak is offline   Reply With Quote
Old 27th January 2006, 15:00   #4
BHPian
 
goldie_malhotra's Avatar
 
Join Date: Nov 2005
Location: New Delhi
Posts: 738
Thanked: Once
Default

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.
goldie_malhotra is offline   Reply With Quote
Old 27th January 2006, 18:34   #5
Senior - BHPian
 
BUSA's Avatar
 
Join Date: Aug 2005
Location: Bombay
Posts: 5,131
Thanked: 6 Times
Default

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
BUSA is offline   Reply With Quote
Old 27th January 2006, 18:39   #6
BHPian
 
Join Date: Oct 2005
Location: chennai
Posts: 636
Thanked: 32 Times
Default

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.
tifosikrishna is offline   Reply With Quote
Old 27th January 2006, 21:41   #7
Senior - BHPian
 
Deeps's Avatar
 
Join Date: May 2004
Location: Delhi/Noida
Posts: 1,044
Thanked: 30 Times
Default

No, because the engine produces the same bhp at a given rpm at any gear. But the ratios do affect the torque.
Deeps is offline   Reply With Quote
Old 30th January 2006, 13:16   #8
Senior - BHPian
 
shuvc's Avatar
 
Join Date: May 2005
Location: Kolkata
Posts: 2,834
Thanked: 240 Times
Default

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 .. ?
shuvc is online now   Reply With Quote
Old 30th January 2006, 15:42   #9
jat
BHPian
 
Join Date: Dec 2005
Location: SINGAPORE
Posts: 265
Thanked: 2 Times
Default

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
jat is offline   Reply With Quote
Old 30th January 2006, 15:58   #10
Senior - BHPian
 
Deeps's Avatar
 
Join Date: May 2004
Location: Delhi/Noida
Posts: 1,044
Thanked: 30 Times
Default

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.
Deeps is offline   Reply With Quote
Old 30th January 2006, 20:06   #11
Senior - BHPian
 
shuvc's Avatar
 
Join Date: May 2005
Location: Kolkata
Posts: 2,834
Thanked: 240 Times
Default

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 ....
shuvc is online now   Reply With Quote
Old 30th January 2006, 20:17   #12
SRK
Senior - BHPian
 
SRK's Avatar
 
Join Date: Sep 2005
Location: Mumbai
Posts: 1,026
Thanked: 57 Times
Default

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!
SRK is offline   Reply With Quote
Old 31st January 2006, 01:20   #13
jat
BHPian
 
Join Date: Dec 2005
Location: SINGAPORE
Posts: 265
Thanked: 2 Times
Default

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 (The Most Powerful Diesel Engine in the world)

RK

Last edited by jat : 31st January 2006 at 01:25.
jat is offline   Reply With Quote
Old 31st January 2006, 16:50   #14
BHPian
 
Beeman's Avatar
 
Join Date: Dec 2005
Location: Treasure island
Posts: 333
Thanked: 2 Times
Default

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.
Beeman is offline   Reply With Quote
Old 29th March 2006, 16:41   #15
BHPian
 
Join Date: Sep 2005
Location: Noida
Posts: 129
Thanked: 0 Times
Default

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
sumitsingh is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Maruti Swift Petrol & CNG Kit - 120,000 kms of a committed relationship! ptaneja Long-Term Ownership Reviews 6 4th February 2013 16:53
Engine Capacity (cc) or Power (bhp)?? karpusv The Indian Car Scene 57 15th September 2012 20:39
Tata Nano's German parts+ Germanys relationship with Indian Auto Industry crazycardude198 The Indian Car Scene 0 3rd November 2010 18:48
BHP CC ratio ashutoshb Technical Stuff 29 17th September 2007 22:17
BHP,kgm,CC. How are they related? ramzsys Technical Stuff 9 25th April 2007 10:16


All times are GMT +5.5. The time now is 14:05.

Copyright 2000 - 2014, Team-BHP.com
Proudly powered by E2E Networks