View Full Version : At what RPM should I shift my stock SC/XR7 when racing?

10-28-2002, 06:52 PM
The 3.8 liter SC V6 engine makes a huge amount of low-end torque. In stock
form, it will generate over 300 ft-lb of torque from approximately 2000 to 4000
rpm. Horsepower output rises gradually with RPM and peaks out around 4400
to 4500 rpm. After this point, the horsepower starts to fall off fairly quickly
due to the insufficient flow capability of the stock cylinder heads and fairly
restrictive exhaust system. Therefore, it really is useless to rev your car more
than 5000 to 5200 rpm. Although the 3.8 liter SC engine will continue to rev
easily (but loudly) past 5500 rpm, the car will not generate faster quarter mile
times by flogging the engine at these higher speeds. Shift at approximately 5000
rpm for optimum power output.

When one has modified the 3.8 liter SC V6 with larger induction and exhaust
components, the horsepower will peak approximately 300 to 400 rpm higher.
Therefore, on a modified SC, you may find that the car still makes power up to
5300 and 5400 rpm. To accurately identify where your optimum shift point
should be, consider getting your car tested on a rear wheel chassis dyno. The
information obtained will be extremely helpful to you, as you will see where
peak HP and Torque are generated.