User Guide

Dyno2000 Advanced Engine Simulation—71
Camshaft Modeling
effective in lightweight vehicles. The Drag-Race/Circle-Track Profile choice can be
used with solid or roller lifters, and the simulation will accurately model this cam with
either lifter-acceleration rate (choose solid lifters for less valvetrain punishing appli-
cations and roller lifters for higher power drag-racing applications). The profile of this
cam is similar to the ISKY Oval Track Flat Tappet Series cam part 201555.
Drag-Race High-Speed Profile—This profile is designed to simulate an all-out
competition aftermarket camshaft. All cam timing events displayed are seat-to-seat
measurements.
All timing events on this camshaft are designed to optimize power on large dis-
placement engines at very high engine speeds with large-tube, open headers, and
high compression ratios. This camshaft may not be effective in small displacement
engines. EVO timing on this racing profile places the utilization of combustion pres-
sure on the “back burner” and focuses emphasis on beginning early blowdown to
minimize pumping losses during the exhaust stroke. This technique will help power
at very high engine speeds, especially on large-displacement engines that do not
easily discharge the high volume of exhaust gasses they produce. The late IVC
attempts to harness the full ram effects of the induction system while relying on
intake pressure wave tuning to minimize intake-flow reversion. IVO and EVC pro-
duce 104 degrees of overlap, a profile that is clearly intended to utilize exhaust
scavenging effects. This very aggressive overlap seriously affects idle quality and
torque below 4000rpm. The characteristics of this cam are extremely lopey idle,
good power from 4500 to 8500+rpm, with no consideration for fuel consumption.
This Drag-Race High-Speed Profile is typically used with roller lifters. The profile of
this cam is similar to ISKY Roller Series cam part 201600.
Note: Each of the previous application-specific cams can be modified in any way by
directly entering valve-event or other cam-timing specs (more on this in the next few
sections).
LIFTER MENU
The Dyno2000 uses sophisticated modeling to simulate camshaft and valvetrain
motion, but you should keep in mind that valve motion curves for both the intake and
exhaust valves are being calculated from only six data points, three for the intake
valve and three for the exhaust valve.
The three points for each simulated motion curve are the opening point, closing
point, and the maximum lobe lift. From these points, and the lifter-type selection, the
program creates motion curves that pinpoint valve lifts at each degree of crank
position. While the results are remarkably accurate, the Dyno2000 cannot model
subtle differences between cam grinds that use the same event timing and valve lift
specs. Furthermore, the Dyno2000 develops a symmetric valve motion curve (mean-
ing that the “opening” side of the lobe has an identical shape as the “closing” side).
Asymmetric modeling is impossible with only three data input points, luckily, perfor-