User Guide

Dyno2000 Advanced Engine Simulation—73
Camshaft Modeling
and finally roller-lifter camshafts. This is
a good assumption, since cams typically
use lifters that are suited for the intended
application, and cam profiles for specific
applications typically apply predictable
valve acceleration rates. However, this
is not always the case. For example,
some camshafts available for mild street
engines use roller lifters, not to achieve
high valve acceleration rates, but to op-
timize reliability. In these cases, choos-
ing roller lifters will produce optimistic
simulated power curves. So, to improve
program accuracy, ask yourself if the
camshaft you are modeling fits the fol-
lowing application-specific description
before you make a lifter selection:
Menu Choice Application
Hydraulic Flat-Tappet Street/Mild Perf.
Solid Flat-Tappet HP/Mild Racing
Roller Very HP/Racing
If the cam you’re modeling is a roller-
lifter grind but incorporates a mild-street
profile, select Hydraulic or Solid Flat-Tap-
pets from the menu, since this choice
will produce a lift curve that best matches
a mild street camshaft. On the other
hand, if the cam is a high-performance—
or high acceleration—grind, select Solid
Lifters since this will model the faster ac-
celeration rates of aggressive perfor-
mance grinds. If you are modeling a
solid-lifter racing cam, like some “mush-
room” lifter grinds, the Solid Lifter choice
may underestimate the acceleration rate
of these competition camshafts. In this
case you may find more accurate pre-
Basic Lifter Choices
R
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Retaining Ring
Pushrod Seat
Oil Inlet
Metering Valve
Adjusting
Oil
Cavity
Check Valve
Lifter Body
Lifter Face
Hydraulic Lifter
Street/Mild
Performance
Lifter Face
R
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Retaining Ring
Pushrod Seat
Oil Metering
Valve
Oil Inlet
Lifter Body
Solid Lifter
High Perf./
Racing
R
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Retaining Clip
Pushrod Seat
Oil Inlet
Check Valve
Adjusting
Oil
Cavity
Lifter Body
Roller Bearings
Lifter Cam Roller
Metering Valve
Roller Lifter
High/Perf.
All-Out Racing
The three lifter choices establish a “ramp-rate” model for the simulated valve-motion
curve. The lowest acceleration is assigned to Hydraulic Flat-Tappet Lifters. The next
highest acceleration is applied to Solid Flat-Tappet Lifters. The highest acceleration is
reserved for the last menu choice: Roller Solid Or Hydraulic Lifters.