SOHC is better then DOHC

[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

 

[ettk2003]

hi

previously i was running a 4G92 sohc, with port & polish head and forged piston too...then i did the dohc conversion as well...and what i found is that for the pick-up its more or less the same but at high rpm i can feel slight increase in hpower...

might need a ecu that is for dohc to fully utilize the new head...i didnt do that so i cant tell u the result..

but the other things i found is that with dohc, the engine is much more quiet, and the sound from the exhaust is much nicer....also looks good with a dohc rather than sohc inside the engine bay :D


cheers

 

[moppy]

Originally posted by ettk2003@Feb 23 2005, 10:46
hi

previously i was running a 4G92 sohc, with port & polish head and forged piston too...then i did the dohc conversion as well...and what i found is that for the pick-up its more or less the same but at high rpm i can feel slight increase in hpower...

might need a ecu that is for dohc to fully utilize the new head...i didnt do that so i cant tell u the result..

but the other things i found is that with dohc, the engine is much more quiet, and the sound from the exhaust is much nicer....also looks good with a dohc rather than sohc inside the engine bay  :D


cheers

Agree too, look nice and more queit that before.

Mine is 4G92 did a conversion, with 4G91 Head. I was in dilema of swapping the head for so long and finally I did it. I hv studied a lot of the 4G91 head and 4G93 and gather up the information. There's a little different between this 2 head.

1) The cams profile different
2) Valve spring - 4G93 is about 5mm higher
3) The valve porting size, needn't to say the smallest is 4G91
4) The piston head, 4G93 is bigger so obviously can see which is 1.5 and which is 1.8.

I hv done a polish but not porting, my mechanics advice me cos might occur pick up power lost. Comparison 4G91 DOHC n 4G92P, the power output is more or less the same therefore 4G92P is ideal to use 4G91 head. His personal opinion said 4G93 head is bigger port as a result might loose a lot of pick up power compare using 4G91.

After the conversion, yes I dmit I loose some pick up power but not much loosing. Anyway still notice the different, at around 3200 rpm I could feel the power is in control until I rev. 7000 rpm without any problem. My car is auto, but normally I rev. until 6000 rpm.


Another case, my brother driving a 4G93P SOHC and he swapped to DOHC. He was conned by a foreman (in Shah Alam, dun go there anymore) said that swapped with 4G93 DOHC. That moron foreman took out the EGT as a result my bro. car disposed a lot of carbon. Then finally I took his car back to my mechanics and overhaul the head. At the end everything restore to be original with EGT and DOHC head. The head finally being ported back to 4G93P valve porting size except the cams. Can't do anything about it cos can't find a 4G93 cams.

The results, my brother car suffer a serious problem at the pick up but has a good top end. Very good top end, and at 120km/h the car still can drop gear. By the way it's auto as well.

The above result might not be the same as in different car and just my bro. n my experience. There are a lot of reason why this has happen.

 

[yiheng85]

read from a book..merc went back to using 3 valves because they wanna incrase fuel efficiency...:) the theory behind it i dunno :P

 

[ettk2003]

ya...agreeded with what moppy said...

my friend did the same conversion with me at the same time, but he was using a 4G93T head whereas i was using a 4G91

we tested both cars after the conversion...and his car is a bit on the slow side in term of pick-up...it takes a while to kick in

cheers

 

[SloMo]

still researching here... what kind of DOHC head suits 4g18p's block?... can 4g15 DOHC mivec from the new lancer fit in?... any other option?...