SOHC is better then DOHC

[softmuffin]

Hi there,
Myself going to change my satria 1.6 (4G92 SOHC) to DOHC(not engine tukar ya) this weekend but the guy told me after to DOHC, my car pick up is not as good as it is now (SOHC). izzit true.
Pls give me some info here cos the cost of the SOHC to DOHC is around Rm900..
thanks..

 

[acbc]

SOHC has better low end than DOHC which has better mid to high end... also, SOHC is lighter.

 

[mengz]

DOHC has better throttle response compared to SOHC...and like wat acbc said...DOHC has better mid to high end power.....but dun expect lotsa hp increase by converting from SOHC to DOHC. let us know how did the mod go ya....cheers!

 

[chiku]

wat the different max rev SOHC compare to DOHC... if SOHC convert to DOHC... izzit max rev will increase or not.... :unsure:

 

[alien]

Originally posted by acbc@Feb 21 2005, 10:18
SOHC has better low end than DOHC which has better mid to high end... also, SOHC is lighter.

really?.. :huh:
it applies to all cars..?

 

[acbc]

Originally posted by alien@Feb 21 2005, 12:42
really?.. :huh:
it applies to all cars..?

Applies to any car...

SOHC has some advantages over DOHC especially same displacement.

 

[chiku]

Originally posted by acbc+Feb 21 2005, 12:46 --></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (acbc @ Feb 21 2005, 12:46 )</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-alien@Feb 21 2005, 12:42
really?.. :huh:
it applies to all cars..?

Applies to any car...

SOHC has some advantages over DOHC especially same displacement. [/b][/quote]
:unsure: can anyone tell me the different...

 

[taqu]

The more complete question is "4G92 12-valve SOHC convert to 4G92 16-valve DOHC, pros/cons?" :) Coz there're 4-cylinder engines having 16 valves but only use SOHC eg Waja engines or some Honda engines.

About pros & cons of 12-valves (3 valve per cylinder) vs 16-valves (4 valve per cylinder), I copy-paste this statement from Autozine :

A typical 2-valve engine has just 1/3 combustion chamber head area covered by the valves, but a 4-valve head increases that to more than 50%, hence smoother and quicker breathing. 4-valve design also benefit a clean and effective combustion, because the spark plug can be placed in the middle.

4 valves are better to be driven by twin-cam, one for intake valves and one for exhaust valves. Honda and Mitsubishi models prefer to use sohc, driving the valves via rocker arms like the aforementioned Triumph. This could be a bit cheaper, but introduce more friction and hurt high speed power. Therefore the sportiest Honda and Mitsubishi still use dohc.

Hmm it is correct to say that generally DOHC engines have abit weaker low-end compare to SOHC (coz DOHC results in larger intake area resulting in slower air flow) , but most DOHC engines have smaller-diameter & curved intake manifold to improve those low-end torque (I think this also applies to 4G92), so u won't notice that low-end loss, on the other hand this may effect hi-end power, but since DOHC have more potential for hi-revving than SOHC, this is OK.

So, gor for it dude :)

 

[tajulsans]

answering on my friends experience, not my personal experiance..

he converted his wira a/b 1.6 from sohc to dohc.. according to him his top speed has reduced abit but pick up really improve..

dont flame me kay.. :)

 

[acbc]

Australia's most powerful SOHC RB30...

http://www.stalkerz.com/RB30.gif

Or download the PDF: http://www.stalkerz.com/RB30.pdf

 

[TiBuN]

I think the new question is : Is it worthwhile to spend the money for a SOHC -> DOHC conversion???

My personal 2 cents, no. Unless you're planning to keep the car for like.... the next 5 years perhaps?

 

[trex92]

Originally posted by softmuffin@Feb 21 2005, 10:08
Hi there,
Myself going to change my satria 1.6 (4G92 SOHC) to DOHC(not engine tukar ya) this weekend but the guy told me after to DOHC, my car pick up is not as good as it is now (SOHC). izzit true.
Pls give me some info here cos the cost of the SOHC to DOHC is around Rm900..
thanks..

Definitely not true. With a DOHC engine, you can afford to rev your RPM higher which would improve your acceleration. SOHC does not perform as efficiently as DOHC at high RPM.

 

[Revo]

Yep. DOHC is good in HIGH rpm....

 

[tajulsans]

i think the better choice is upgrading the head to Mivec.. cost should be about 1.3k - 1.5k.. can rev much higher than normal dohc..

 

[TypicalGuy]

wonder why mercedes still using SOHC 3 valve tech

 

[tajulsans]

i suppose because merc engine are normally high displacement.. dont think u wanna rev high kan.. fuel suffer oh.. there for low end power is the better choice loo

 

[donchichi]

Sorry to bug in this thread but just to take note that you're doing a SOHC to DOHC conversion. Your original block is not meant to take in the higher revs of a dOHC/Mivec head. Unless the block is the same as the DOHC block. ?

I'm not familiar with Mitsubishi engines so that's just my short assessment. How much can your block take? Similarly a standard B18 (non vtec) honda engine can't rev higher then a B18 (vtec) if you swap the heads around you still can't rev higher without internals being upgraded.

cheers

 

[trex92]

Originally posted by donchichi@Feb 22 2005, 12:30
Sorry to bug in this thread but just to take note that you're doing a SOHC to DOHC conversion. Your original block is not meant to take in the higher revs of a dOHC/Mivec head. Unless the block is the same as the DOHC block. ?

I'm not familiar with Mitsubishi engines so that's just my short assessment. How much can your block take? Similarly a standard B18 (non vtec) honda engine can't rev higher then a B18 (vtec) if you swap the heads around you still can't rev higher without internals being upgraded.

cheers

The block wise should be fine. DOHC engines has higher rev thresholds due to more efficient valves manipulation arising from the double camshafts used. On the other hand, SOHC has lower rev threshold as it only has 1 cam to do the job hence not so efficient at high revs.

 

[amad108..]

Originally posted by softmuffin@Feb 21 2005, 10:08
Hi there,
Myself going to change my satria 1.6 (4G92 SOHC) to DOHC(not engine tukar ya) this weekend but the guy told me after to DOHC, my car pick up is not as good as it is now (SOHC). izzit true.
Pls give me some info here cos the cost of the SOHC to DOHC is around Rm900..
thanks..

yes it's true, maybe u use 1.8 DOHC head.... if u using 4G91 head the pick-up a lot increase coz the hole smaller then before n the efficiency of DOHC normally for fine tuning compare SOHC....

my friend's done head 1.8 for his 92 engine, the car become really slow la... he said maybe cannot match the head n the block...

my opinion just stay with SOHC, upgrade valve spring+street cam+ecu chip tuned that's enough....

 

[softmuffin]

Hi guys,
myself really in dilemma rite now..
Some say DOHC to SOHC = good but some say no
All i want is more power not after DOHC to SOHC my car be more worst.
BTW i be buying monroe shock for my front and real this sat around RM600
care tell me what you all think about monroe compare to KYB (Rm400)

 

[najibkl]

What i alwayz "kena"...My car is SOHC, alwayz kena tapau at first gear with kelisa. But now, goodbye kelisa.

So, the point is DOHC much pick up than SOHC ler

 

[NukeeZoid]

Originally posted by najibkl@Feb 22 2005, 14:55
What i alwayz "kena"...My car is SOHC, alwayz kena tapau at first gear with kelisa. But now, goodbye kelisa.

So, the point is DOHC much pick up than SOHC ler

you running a DOHC head now??

i was also thinking about this upgrade...to change my head from the SOHC to the DOHC one....im running a satria 1.6 as well...

thats why im wondering whether its worth the cost. changing the head like that would cost about RM900-RM1000...

if i add another RM500 more i can port and polish my engine which would gain me about 8-10BHP....

is the cost for head swapping justified? :blink:

 

[AccordRacing]

i think SOHC for FC n nice pick up at city area(cause SOHC is lighter)
DOHC for performance n FC at high speed compare with SOHC

 

[lozo]

from my understandings
DOHC engine is much more refined, giving it more hp and it can withstand high revs.
SOHC is lighter, less components..therefore being light, it provides good response esp. in the low rpm's

 

[reddice]

update us if you have done your swap to DOHC head..i also wanted to swap..but must see first la..more benefit or not..if same..better use SOHC..

p/s : but they say,using dohc "jimat minyak" la.and more power to..thay say la... :D :D