What's the difference between SOHC & DOHC? Which one is better & why?

Question

I'm getting a Nissan Xtera with a V6 engine but I want to know which overhead camshaft should I get with it. A SOHC or a DOHC?

Answer 1

single or two over head cams
the duel may have more power
but you probally wont notice the differance
cost of matinance on the dohc will be more

Answer 2

A dual overhead camshaft allows the intake and exhaust valves to be mounted at more of an angle to the cylinder, allowing for better flow (of the fuel and air/exhaust) and more power.

Most single overhead camshaft engines have only two valves per cylinder which restricts flow at high power/high RPMs. Some SOHC engines use a rocker arm arrangement to have four valves per cylinder (two intake and two exhaust) but it can never be as efficient as a DOHC engine.

DOHC engines are almost universally have four valves per cylinder and produce more high end power.

For normal driving you might not even notice the difference. In fact, unless you are redlining the engine all the time, the DOHC engines tend to have less torque.

Answer 3

SOHC = Single Over Head Cam & DOHC = Dual Over Head Cam. Because fewer valve stems or lifters rest on the dual overhead cam, you have less vibration on the cam shaft... but this requires more gears or a longer chain to the crank shaft that turns these cams. Because the DOHC allows better positioning of valves to the cylinder, many times that allows better fuel & exhaust flow.
All other things being equal, I'd pick the DOHC... but check the torque & HP on the engine if you are looking for more go.

Answer 4

You know, oce you post a question on here, the question gets answered by a whole bunch of people. How many of them own Xterra's?

I DO! And I have about 8 grand invested in mine.

It looks like you are getting the second generation Xterra (05'-07')

One thing that I recommend to every vehicle owner is to join a forum.

What is a forum? A forum is a place where a whole bunch of owners of that make and model get together and discuss everything about it.

If you are looking for the perfect website for you, join any one of these.....
http://thenewx.org/index.php

www.xterraownersclub.com(this site might be down at this time)

http://www.xterrafirma.com/

http://www.clubxterra.org/index.php?page=home

From there, you can even find local xterra clubs.

If you were asking a question about the first generation, then I would definitely be able to help you.

By the way, SOHC is single overhead cam,and DOHC is dueal overhead cam. This is no "better" and I am surprised that Nissan offered this as an option. It all depends on the application.

Those forums will save you thousands of dollars and you will be able to self diagnose problems with your vehicle.

Good luck my fellow Xer! When you do join, my screen name is soccerbrace. Later bro!-Hope to see you on the boards!-James

Answer 5

I don't believe you have this choice. If what you are asking is should you buy a newer (2005 or newer) used model for the bigger, better engine, then the answer in the car world is generally considered as YES, buy the newer one. The engine difference is significant.

Answer 6

Both are good. One should get over 100,000 milies on the engine. There really isn't any difference. When the hood is closed you can't tell the differance.

Answer 7

single cam or dual cam, dual is suppose to be more efficent and better