On the New Viper
So I was reading about the new Viper engine...
Taken from: http://www.edmunds.com/insideline/do/Drives/FullTests/articleId=122304
The biggest trick here is the 8.4-liter V10's variable cam-phasing device known as Cam-in-Cam. Variable valve timing is mechanically straightforward for DOHC applications, but an OHV engine with a single cam mounted within the block as found in the SRT-10 presents a challenge.
Here the hollow camshaft has fixed intake lobes on its outer circumference, while the exhaust lobes are attached to separate, movable inner shaft. A computer-controlled mechanism in the cam sprocket continuously adjusts the relative phasing between the two shafts. As a result, the valve overlap can be made radical enough for maximum power or conservative enough for a smooth and clean idle.
A surprising benefit is a 17 percent increase in fuel economy for this new V10. While the 2006 Viper was rated at 11 mpg city and 19 mpg highway (adjusted for 2008 equivalency), the 2008 Viper is good for 13 mpg city and 22 mpg highway. Plus a buyer of a 2008 Viper pockets a $1,700 savings in gas-guzzler tax.
...wow. I want one.
Taken from: http://www.edmunds.com/insideline/do/Drives/FullTests/articleId=122304
The biggest trick here is the 8.4-liter V10's variable cam-phasing device known as Cam-in-Cam. Variable valve timing is mechanically straightforward for DOHC applications, but an OHV engine with a single cam mounted within the block as found in the SRT-10 presents a challenge.
Here the hollow camshaft has fixed intake lobes on its outer circumference, while the exhaust lobes are attached to separate, movable inner shaft. A computer-controlled mechanism in the cam sprocket continuously adjusts the relative phasing between the two shafts. As a result, the valve overlap can be made radical enough for maximum power or conservative enough for a smooth and clean idle.
A surprising benefit is a 17 percent increase in fuel economy for this new V10. While the 2006 Viper was rated at 11 mpg city and 19 mpg highway (adjusted for 2008 equivalency), the 2008 Viper is good for 13 mpg city and 22 mpg highway. Plus a buyer of a 2008 Viper pockets a $1,700 savings in gas-guzzler tax.
...wow. I want one.