RPM ?

[Mopar-man]

Why does the 8.4 liter engine rev higher (making power) than the 8.3 liter engine ?

[Peter Nielsen]

And why does it idle higher? My 2006 was idling around 650 rpm. My 2008 idles around 850 rpm...

[Viper Specialty]

Are you asking why it physically is able to rev higher, or why it makes more horsepower at higher RPM's?

Basically, it has a lighter & more stable valvetrain that allows higher revving without power-robbing valve float. [ignoring the oil system changes that help its ability to live at high RPM's]

The reason it makes more power at high RPM is primarily due to its head and manifold design. Air & Fuel= Torque. Torque at high RPM's= Horspower. Since the engine can rev higher, and is able to flow more combustible gases at those RPM's, it makes more horsepower as a result. The older engines can actually produce more torque at many different RPM's, but they run out of breath at higher RPM, limiting their horsepower in comparison to the Gen-4. This is also why Gen-2/Gen-3 Vipers have seen such drastic gains from a head and cam package, they are pretty weak on the flow charts in stock form... not so with the Gen-4.

[Flash1034]

More importantly, when are we going to see a tuner program to get rid of the throttle lag and boost the HP?

Flash