Difference VTEC Sohc & Dohc

[Wolverman]

What's the difference between the SOHC and DOHC. I have read up on the

definitions but I still don't understand.

 

[Route88]

SOHC are lighter and cheaper to mass produce,but performance wise...DOHC is much prefered to wring tat

high rpm at redline.Until now,SOHC in Honda can do about better torque at mid range and good f/c

[Wolverman]

The full explanation is available in this encyclopedia:

http://www.encyclopediadramatica.com/index...st_Kicked_In_Yo

[Apollo]

SOHC = Single Overhead Cam

 

DOHC = Double Overhead Cam

 

 

SOHC = 2 valves (1 intake and 1 exhaust)

 

DOHC = 4 valves (2 intake and 2 exhaust)

 

Hope I'm correct also

 

cheem... i only know

 

SOHC and DOHC.. machiam missionary position, up and dw ramming

 

VTEC machiam bakuke

[Wolverman]

In Vtec language,

 

SOHC = Turbocharged

 

DOHC = Twin Turbocharged

[Mirrorimage]

Then how come a 92' civic vti DOHC opens once

and a 96' civic Sir DOHC opens twice?

 

Sorry ah.. I'm a noob to VTEC

 

92vti b16a2 is about the same as the 96sir b16a4, just that the b16a4 got about 10 more bhp.

both vtec open once.

 

if u say vtec open twice, should be the b18c (integra dc2)

 

 

you are wrong. B18C has only 2 stage Vtec engine. (meaning open once).

 

 

The 3 stage Vtec engine ("open" twice) is made for a non performance engine known as the D series. Those are all SOHC.

 

Thumbs up for the attempt to contribute though.

[Heeltoenoob]

If you guys have nothing to contribute, don't post.

 

All the OT posts are one reason why such threads keep reappearing cos people don't get the answers they are looking for.

[Route88]

 

[Mirrorimage]

The opening of the intake valves and exhaust valves are governed by the degree of the cams.

 

Thus if you are SOHC, you are using one timing for both intake and exhaust.

 

Engineers found that to be rather limiting for performance thus DOHC, (two cams) were used.

 

Intake cam: This cam is used to control the opening and duration of the opening of the intake valves.

 

Exhaust cam: same as about but this time it is for the exhuast valves.

 

This way, tuners can set different degrees for the cams.

 

At high RPMs, the opening of both the intake and exhaust valves have some form of overlap, thus tuners can set the exhaust valves to close a little later, forming a srong vaccum in the combustion chamber, thus when the intake valve start to open, air is sucked in very strongly.

[Mirrorimage]

SOHC = Single Overhead Cam

 

DOHC = Double Overhead Cam

 

 

SOHC = 2 valves (1 intake and 1 exhaust)

 

DOHC = 4 valves (2 intake and 2 exhaust)

 

Hope I'm correct also

 

Wrong. SOHC means one Cam controlling the intake and exhaust valves. DOHC means two cams. One controlling intake Valves, the other controlling exhaust valves.

[Wolverman]

Wow sounds interesting...

 

Turbochargers force air into the engine... Vtech technology make the engine a super sucker to suck more... interesting

[Apollo]

i tokking to porky leh not u. so gan cheong for wat?

[Wolverman]

Aiyo.. cannot take joke one this one.. alert everyone dont joke about vtech already lah...

[Dynaway]

yup... number of cams does not institue to number of valves.

 

No. of valves depend on cylinder head design and combustion chamber design..

 

more commonly in-line 4 DOHC engine would normally have 16 valves, only a few uses 20 valves(3 intake, 2 exhaust)

 

8, 12 valves would be more common on SOHC engine.

 

 

DOHC are better due to more precise cam timing (valve opening, duration etc)

 

 

VTEC engine are jus having additional high profile lobes on the cam for switch over(Vtec kick-in)

[Wolverman]

Thanks.. your post made it clear..

BTW are you a Vtech-er? (meaning driving a Vtec enhanced engine?)

[Quantum]

my previous ride was city vtec, but it ever was eaten by VVT-i corolla G9, shame to talk

years ago, on highway I runned at about 110km/h on extreme right lane, a corolla G9 tailgated me a while, then shifted to left lane tried to overtake me, I floored my throtle (tot Vtec kicked in aready), but the corolla G9 still could overtake me and shifted back to extreme right lane in front of me

why did my vtec not work

[inline Vtc_nazi.jpg]

Edited September 10, 2007 by Quantum

[Turbonetics]

 

Then how come a 92' civic vti DOHC opens once

and a 96' civic Sir DOHC opens twice?

 

Sorry ah.. I'm a noob to VTEC

 

92vti b16a2 is about the same as the 96sir b16a4, just that the b16a4 got about 10 more bhp.

both vtec open once.

 

if u say vtec open twice, should be the b18c (integra dc2)

 

 

you are wrong. B18C has only 2 stage Vtec engine. (meaning open once).

 

 

The 3 stage Vtec engine ("open" twice) is made for a non performance engine known as the D series. Those are all SOHC.

 

Thumbs up for the attempt to contribute though.

 

not all D series engine have 3 stage vtec.

only the EK3 Vti.they have 2 vtec solenoids.

some D series can be make to perform but ofcourse not as optimum as B series.

[Llfr]

Actually I'm asking more about VTEC SOHC and VTEC DOHC

 

So which engine models "open" twice and which are the ones that "open" once