Re: <tech> DOHC vs. SOHC

["John Huntoon" <bmwhunt@xxxxxxxxxxx>]

Christopher Pawlowicz wrote:

> KC asks
> >What's the advantage of having two cams versus one?  I can see an
> >advantage with VANOS on one or both (more leeway for adjustment).  > 
Is
> >there anything else that two cams do better than one?
> >
> 
> don't you *have* to have 2 cams to work a multi valve engine ?
> 
> if you have 2 valves per cylinder they can be side by side (in the 
same
> direction as cylinders) and 1 cam can operate both valves..
> 
> but if you want 3 or 4 (or more?) valves per cylinder you have 
> a cluster of 4, and 2 can be operated from one side, but the other
> two have to be operated from the other side of the bank of cylinders
> which means another cam
>  
> is there such a thing as a sohc multivalve engine ?

Chris,

One problem is that with 4 valves in a combustion chamber, the spark
plug would naturally want to be in the center, but if there's a cam
over the center, there's just no room. With two cams, there's more
room to position the plug.

JH

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