Difference between DOHC Vtec and SOHC i-vtec

[Bob san]

Just wondering what are the main differences between DOHC vtec and SOHC i-vtec.

[**Ghost**]

Essentially speaking the biggest difference is the number of camshafts the engines have.

DOHC = DUAL overhead camshafts

SOHC = SINGLE overhead camshaft

DOHC engines are designed to rev higher, have peakier power outputs and PERHAPS high horsepower application.

SOHC engines are designed to make power low in the rev range, have more usable power for daily driving.

[Bob san]

So does that mean DOHC is usually more powerful then SOHC?

[yeehou]

DOHC refers to Double Overhead Camshaft. This arrangement uses two camshafts in each cylinder head. Two cams per cylinder head means that a DOHC V engine has 4 camshafts because it has 2 banks of cylinder heads. Most of the time it also allows the engine to rev higher. It also allows better placement of the valves in an optimized setup that gives you maximum performance. But the disadvantage of such a setup is more weight, more cost and more complexity. (copied from a website)

[marte]

ivtec = vtec (valve timing & lift control) + VTC (Variable overlap timing control)
the vtec is the same as the current DOHC B Blocks but with something new vtec-e, this is something that concentrates on mild cams.
ivtec is the way to go.

[Sexc86]

dam i am waiting for weq to have his 2 cents

[aimre]

DOHC refers to Double Overhead Camshaft. This arrangement uses two camshafts in each cylinder head. Two cams per cylinder head means that a DOHC V engine has 4 camshafts because it has 2 banks of cylinder heads. Most of the time it also allows the engine to rev higher. It also allows better placement of the valves in an optimized setup that gives you maximum performance. But the disadvantage of such a setup is more weight, more cost and more complexity. (copied from a website)

Well our engines are straigh fours, so we got one head, and onyl two cams in total.

[marte]

plus i-vtec enginesa are newer lol

[ROLLED]

ivtec = vtec (valve timing & lift control) + VTC (Variable overlap timing control)
the vtec is the same as the current DOHC B Blocks but with something new vtec-e, this is something that concentrates on mild cams.
ivtec is the way to go.

personally, I wouldn't listen to a man who resprayed his car green! LOL

[marte]

personally, I wouldn't listen to a man who resprayed his car green! LOL

haha you idiot ill put pink paint on ur car

[Limbo]

I believe the SOHC does not have lift whilst the DOHC has lift feature in the Vtec.

SOHC only has timing adv.
DOHC has Cam profile change & timing adv, ignition and exhaust.

[aaronng]

SOHC VTEC = Timing and lift change in 1 step. Usually used to maximise low end torque. Because 1 cam controls both intake and exhaust valves, you cannot get good timing for high RPM power.

DOHC VTEC = Same as above, but because intake and exhaust are on separate cams, you can have very wild cams timings, duration and lift for high-cam.

VTEC-E = VTEC is used to close 1 intake valve at low RPM. So it operates at in 12 valve mode in low RPM for torque and 16 valve mode at middle to high RPM. Intake cam has 2 lobes but 3 followers. The extra follower is for the closed intake cam.

3-stage VTEC-E = Same as above, but in addition to 12v and 16v, there is a a 3rd stage where the large middle cam love for intake is used. So you have more power.

SOHC VTEC (Jazz): has 12v and 16v mode like VTEC-E.

i-VTEC (DOHC low performance, CRV, Accord): VTEC only on the intake cams, and also VTC on intake.

i-VTEC (DOHC high performance, DC5R, DC5S, Accord Euro): VTEC on intake and exhaust cams, and VTC on the intake cam.

i-VTEC SOHC (new, 2006 Civic): At low loads, the intake valve closure is delayed well into the compression stage so that part of the intake goes back out the intake valves. This reduces pumping loses for low load situation. At high load or heavy throttle, the intake valve closure becomes normal using VTEC, so it works like a normal engine. Those who know their engine types will notice that this is a Miller Cycle-type engine when the intake valve closure is delayed. Plus, VTEC can be activated at ANY RPM! A hydraulic pump increases the pressure of the engine oil at low RPM so that there is sufficient pressure to use the VTEC system. Oh, and VTC on the intake cam.

And yes.... I wrote this all from memory.