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AUTOMOTIVE CAMSHAFT DYNAMICS 541
results in overstressing the spring and increasing enormously the number of stress cycles,
with a consequent fatigue break of the spring, followed perhaps by breakage of other parts.
Noise, the least important result, is also caused by bouncing of the valve and surging
of the spring. The former produces valve clatter, and the latter produces spring hum and
coil clash.
16.7 ENGINE PERFORMANCE
The performance of the engine is the confirmation of the camshaft valve-gear performance.
Software is available to study this subject in “virtual” engines, analyzing one cylinder of the
automotive engine. In the old days this requirement (see Fig 16.1) was based on experience
when designing an engine. The following software packages to be utilized are listed in
App. D:
AIR FLOW TESTING
CAMPRO
CAMPRO PLUS
DESINE
DOCTOR DOCTOR
DYNOMATION
ENGINE EXPERT
FLOW QUIK
SWIRL METER
UTILITY ENGINE PROGRAMS
SPRING MASTER
VALVE PRO
It is to be noted that DYNOMATION and ENGINE EXPERT programs are computer
simulations of dynonometer studies. Both these software programs are indeed valuable in
producing a strong engine.
Last, the designer measures the air flow in the intake and exhaust systems and models
the engine on the computer with empirical data based on experience. The final assembly
and engine testing of the actual engine on the dynamometer will proceed quite properly.
16.8 SUMMARY
The following are some brief thoughts on the subject of automobile camshaft dynamics:
• The subject of this chapter can be applied to any internal combustion engine with an
Otto or diesel cycle, two or four stroke, such as racing cars, street cars, motorcycles,
and diesel engines.
• The automotive camshaft directs the engine to “breathe.”
• Manufacturing quality is critical to the best performance. Proper alignment of the assem-
bled parts must be achieved.
• For the ultimate manufacturing level use the newest machine tools, the highest quality
materials (cost), and the most skilled and talented hands-on artisans.
