RSR Inlet Runner and Peak Torque Calculator
Calculations for a dynamic running engine are complex as we are dealing with camshafts, exhaust systems, and the larger issue of the cylinder head design. For a more comprehensive look at this from a simulation standpoint a $600.00 program like Dynomation may do more to answer your curiosity.
The calculators on this page will help you plan your attack on cylinder
head selection, valve and port sizes and allow you to coordinate your
camshaft and exhaust system selection. This page is not designed to
answer the questions for turbo or supercharged applications, which is a
topic for another day. Generally, in the case of a Harley Davidson
V-Twin an LSR 2-1 collector system will do wonders to increase torque.
Both RB Racing LSR 2-1 and RB Racing LSR 2-1 Pro Stock Systems are available for both oem and aftermarket heads as well as 113/132" ORCA motors with S&S Special Application "SA" heads
in mind that these calculations must be used in conjunction with header
tube diameter and length, valve size, head flow, and camshaft
selection. For instance, if your camshaft is designed to peak at 4500
RPM, but your manifold and headers are tuned for 6500 RPM, your actual
torque peak will fall somewhere between 4500 and 6500 RPM, and the
useable torque band from 2500 to 4500 rpm will be lengthened and
flattened. On the other hand, if you match the intake, headers, heads,
and camshaft all for 5000 rpm, the torque peak will fall very close to
5000 RPM. Also, keep in mind that peak torque and peak horsepower do
not occur at the same rpm and that when you shift it is always better
to fall back to a region of maximum torque instead of trying to "climb
the mountain" to get back to your next redline shift point. We cannot
emphasize enough that you must view the engine as a complete system and
not concentrate on only one aspect of it..