Two valves per cylinder

[Maelfyn]

Why would the Viper use two valves per cylinder? We sure as hell don't see 4 bangers running around with 8 valves! haha, though I'm sure different things work better depending on how many cylinders you're working with.

Also, what valve characteristics are better for performance on SOHC and on those rusty pushrod dumbestic engines? For example, I know a wider valve angle is generally better for performance on DOHC engines. Are SOHC valves always parallel to each other, or can they be at an angle like DOHC engines?

What about actual valve diameter? I don't believe I've seen this specified in engine specs before but I would think it would be important.

[yakkosmurf]

The Viper only needs two valves per cylinder. The valves are a lot bigger on that engine than you'll find on 4 cyl. They don't need two valves to get enough air into the combustion chamber. Also, it's a matter of cost. V DOHC engines are expensive to design and build. With the pushrod setup, the Viper can make the HP they want, with a cheaper cost. Pushrod engines also have better low end power. The single valve arrangement provides more turbulent flow at low rpm, and this results in a more complete burn of the intake charge.

As for SOHC and DOHC engines, there are a variety of different valve arrangements you can go with. Most SOHC setups use rocker arms just like a pushrod engine. They also usually have 2 or 3 valves per cylinder. You could setup a mechanism to run a SOHC engine with the same arrangement as a DOHC, but why would bother with the effort and expense?

Valve diameter is a function of a few things. First, what kind of flow do you want or need at different rpm. Also, is the engine going to provide low end power or high end power. How big are your pistons? You have to have room to place the valves over your pistons.

[nxracer]

Of course most people don't know the Viper engine started life in a Truck

[Gaps]

Originally posted by nxracer
Of course most people don't know the Viper engine started life in a Truck

So thats is why they sound like bad a$$ milk trucks!