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


Reply
 
Thread Tools Search this Thread
Old 15th April 2007, 15:22   #1
BHPian
 
raajks's Avatar
 
Join Date: Aug 2005
Location: BLR
Posts: 578
Thanked: 117 Times
Lightbulb Driving style for DOHC and SOHC

Do we need a different driving for DOHC and SOHC?

For DOHC's, the engine comes to life at higher RPMs, so we would need to rev the higher than what we would normally do for a SOHC before shifting up.

SOHC, delivers an excellent low end torque and flattens out at higher RPMs.
Would love to hear your thoughts on this.

Here is a cool link on a video on &

Last edited by raajks : 15th April 2007 at 15:25.
raajks is offline   Reply With Quote
Old 15th April 2007, 15:26   #2
Senior - BHPian
 
abhibh's Avatar
 
Join Date: Sep 2005
Location: Back in the HOOD near you!
Posts: 2,767
Thanked: 33 Times
Default

Quote:
Originally Posted by raajks View Post
For DOHC's, the engine comes to life at higher RPMs, so we would need to rev the higher than what we would normally do for a SOHC before shifting up.

SOHC, delivers an excellent low end torque and flattens out at higher RPMs.
Would love to hear your thoughts on this.
This is news to me. I thought that major difference between DOHC and SOHC is the CamShaft.
abhibh is offline   Reply With Quote
Old 15th April 2007, 18:11   #3
Senior - BHPian
 
v1p3r's Avatar
 
Join Date: Feb 2005
Location: BLR - chasing cars...
Posts: 4,836
Thanked: 26 Times
Default

Info is wrong. "Coming alive" at higher RPM depends on the characteristics of the camshaft(s) and the engine, be it SOHC or DOHC. Have seen SOHCs with no pull until 6000 rpm, then manic pant-wetting power till 14000 rpm. And DOHCs with immense low-end torque.
v1p3r is offline   Reply With Quote
Old 15th April 2007, 21:03   #4
BHPian
 
Join Date: Feb 2007
Location: Bangalore
Posts: 191
Thanked: Once
Default

generally, DOHC's should be able to do everything that an SOHC does well, and better. Most engines, unless they come with variable valve timings, would be rated for one particular kind of use - cruising, dogfights, etc, so independent of their cylinder head and camshaft design, you will find differences between engines.
wizardofid is offline   Reply With Quote
Old 15th April 2007, 22:57   #5
BHPian
 
Join Date: Apr 2007
Location: Chennai-not at home now
Posts: 100
Thanked: Once
Default

I am not sure if that is neccessarily true. Theoretically, we could have a SOHC that could be be a dud at lower rpms and vice versa for the DOHC. As far as the driving style of the car goes, drive the car with its merits in mind. sohc, dohc and vtec or what not, in the end what matters is how the power comes through.
Sparkie is offline   Reply With Quote
Old 16th April 2007, 13:54   #6
BHPian
 
raajks's Avatar
 
Join Date: Aug 2005
Location: BLR
Posts: 578
Thanked: 117 Times
Default

v1p3r -- You are right.
What I meant was DOHC (CAM component) is heavier that SOHC
With a right timimg belt, SOHC can have a higher torque when compared to a DOHC as the amount of energy that is needed to time and lift two valves would be lesser that what would be required for the SOHC's

If you notice, most of the JAP's employ SOHC's
Whereas European and driver or race oriented car were DOHC.

The intention of the thread was to share a video on the internal workings of DOHC.
Thanks for the "light of knowledge" folks
raajks is offline   Reply With Quote
Old 16th April 2007, 14:02   #7
BHPian
 
theEnd's Avatar
 
Join Date: Nov 2005
Location: Bombay
Posts: 534
Thanked: 5 Times
Default

If you compare a DOHC and a SOHC - everything else being the same - the DOHC would be superior because it offers more precise timing of both the inlet and the outlet cams. This is the major benefit. Sure, the DOHC will be slightly heavier and will require slightly more energy for the second camshaft, but this is usually negligible.

But every engine will have different characteristics, regardless of SOHC/DOHC.
theEnd is offline   Reply With Quote
Old 16th April 2007, 14:56   #8
BHPian
 
sbasak's Avatar
 
Join Date: Nov 2005
Location: CCU-LTN
Posts: 607
Thanked: 8 Times
Default

One's driving style should not be changed whether it is DOHC or SOHC.

To drive any engine optimally, all you need to know is the power torqure characteristics (ie. at what RPM what torque is produced) - so that you can get max. fuel efficiency.
sbasak is offline   Reply With Quote
Old 16th April 2007, 15:41   #9
BHPian
 
WhiteKnight's Avatar
 
Join Date: Mar 2006
Location: Bangalore
Posts: 828
Thanked: 73 Times
Default

Quote:
Originally Posted by raajks View Post
With a right timimg belt, SOHC can have a higher torque when compared to a DOHC as the amount of energy that is needed to time and lift two valves would be lesser that what would be required for the SOHC's
What are the "two valves" you are refering to? Would you please explain?

Quote:
Originally Posted by raajks View Post
If you notice, most of the JAP's employ SOHC's
Whereas European and driver or race oriented car were DOHC.
If I notice, there is a shift to DOHC by almost all manufacturers. I cannot see any Japanese maker still sticking with SOHC. Would you please back up with data?

I thought the primary driver for the shift to DOHC is better placement of valves that is possible with twin cams.

Afterall cams has got nothing to do with nationality

Last edited by WhiteKnight : 16th April 2007 at 15:42.
WhiteKnight is offline   Reply With Quote
Old 16th April 2007, 18:00   #10
Senior - BHPian
 
v1p3r's Avatar
 
Join Date: Feb 2005
Location: BLR - chasing cars...
Posts: 4,836
Thanked: 26 Times
Default

The no of valves is totally independent of the no of camshafts. And you'd be hard pressed to find a single Jap manufacturer still selling an SOHC internationally.
v1p3r is offline   Reply With Quote
Old 16th April 2007, 18:10   #11
BHPian
 
raajks's Avatar
 
Join Date: Aug 2005
Location: BLR
Posts: 578
Thanked: 117 Times
Default

Honda ZX -- SOHC
Mitsubishi Lancer Cedia -- SOHC
raajks is offline   Reply With Quote
Old 16th April 2007, 18:23   #12
Senior - BHPian
 
v1p3r's Avatar
 
Join Date: Feb 2005
Location: BLR - chasing cars...
Posts: 4,836
Thanked: 26 Times
Default

So is the Ford Ikon and Fusion, and I think Fiesta too. And how about the Palio 1.2? And the Logan 1.4 and 1.6? And while we're at it, I'm not sure about the Aveos...
v1p3r is offline   Reply With Quote
Old 16th April 2007, 18:58   #13
BHPian
 
sbasak's Avatar
 
Join Date: Nov 2005
Location: CCU-LTN
Posts: 607
Thanked: 8 Times
Default

Honda is selling Jazz with SOHC (source Honda (UK))
sbasak is offline   Reply With Quote
Old 16th April 2007, 21:26   #14
Senior - BHPian
 
Shan2nu's Avatar
 
Join Date: Feb 2004
Location: Hubli - Karnata
Posts: 5,525
Thanked: 87 Times
Default

More than the number of camshafts, it's the engine's state of tune and design.....that decides how and where it gets it's power.

Honda's 3ltr V6 (244bhp) used in the Accord Coupe and the 3.5 ltr V6 (297bhp) used in the Acura RL are both SOHCs, but do you realise this when you drive them?

Forget that, i've driven highly tuned OHC Vtecs that have very little to offer at low rpm but are unbelievably quick once you cross 5000 revvs. Compare that to my stock Vtec that has very good low end grunt but just cannot match the tuned ones, up the revv band.

Shan2nu

Last edited by Shan2nu : 16th April 2007 at 21:29.
Shan2nu is online now   Reply With Quote
Old 16th April 2007, 22:15   #15
BHPian
 
chetanhanda's Avatar
 
Join Date: Mar 2005
Location: Toronto
Posts: 886
Thanked: 42 Times
Default

basically you have got everything completely wrong.

Quote:
Originally Posted by raajks View Post
v1p3r What I meant was DOHC (CAM component) is heavier that SOHC,

whats this ?
Why would you think like this ? so what if its heavier ? just becoz (even if it was) it is heavy doesnt mean SOHC is better than DOHC

Quote:
Originally Posted by raajks View Post
With a right timimg belt, SOHC can have a higher torque when compared to a DOHC as the amount of energy that is needed to time and lift two valves would be lesser that what would be required for the SOHC's
no way .. how can you say that SOHC has better torque than DOHC ?? becoz SOHC weighs less..
and what do you mean by timing belt... since when did the "right timing belts" decide torque curves..

Quote:
Originally Posted by raajks View Post
If you notice, most of the JAP's employ SOHC's
Whereas European and driver or race oriented car were DOHC.
hey wait.. you are going totally off now by saying Jap cars are SOHC and not driver or race oriented...
chetanhanda 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
8 Valve SOHC vs 16 Valve SOHC shineshine Technical Stuff 6 12th February 2016 22:23
Honda CB 750Four SOHC Xantos Superbikes & Imports 16 21st August 2015 12:59
Converting Esteem SOHC to DOHC MustangMan Modifications & Accessories 9 7th July 2014 17:54
Which engine is better? SOHC vs DOHC abhibh Technical Stuff 26 9th October 2010 02:45
Top stable speed on Accent GLS SOHC! rchandan The Indian Car Scene 19 6th February 2008 15:59


All times are GMT +5.5. The time now is 16:13.

Copyright ©2000 - 2017, Team-BHP.com
Proudly powered by E2E Networks