The higher you can rev the race engine (providing it can breath well) the higher the power output. The valve train has been one of the major roadblocks to trying to achive these higher RPMs. At high RPM, the mass in the valve train puts trememdous strain on the pushrods and other components as you try to get the seated valve to open, then keep it from lofting or tossing off the nose of the cam, then keep it from slamming closed and bouncing off the seat. All this has to happen in about 1/200 second at about 10,000 RPM. For you camara buffs, think of a shutter speed of 1/200. For you physicysits and drag racers, the valve can be going through 2000 Gs or more. That’s fast.
Lots of technological advances have been made over the years, lighter and stiffer components, more durable valve springs materials and designs, 4 valve engines (2 smaller valves instead of 1 large valve), etc. Lots of tools have been used to understand and develop these valve train advancements, including computer tools. One such tool is valve train computer simulation. Another is a valve train “dyno” like the Spintron.
Our Engine Analyzer Pro includes a valve train simulation. You can choose to turn it On or Off. If you turn it On, you will have to be careful to enter accurate spring rates, valve train weights and effective rocker arm stiffness. However, with it turned on, you can learn a tremendous amount about how valve trains work at high speed.
In late 1980s, when we started to develop the Engine Analyzer Pro, we knew that valve train dynamics was critical to good engine power production. For example, assuming a perfect valve train the valve should be open, say, .030″ on the opening ramp. 
But due to inertia and valve train bending, it is likely still on the seat at 7000 RPM! Therefore, we needed a good valve train dynamics simulation. We worked with Tim Gillespie of Comp Cams who shared some pushrod force data. With just a little bit of tweaking of the damping (friction) factors, the Engine Analyzer Pro’s predicted forces were almost “spot on” with what Tim had measured. 
It all makes sense that you want light components, strong valve springs, and a cam profile which is agressive enough to open the valve enough for good flow, but not overly agressive. However, the flexibility in the valve train is another, often overlooked critical aspect to valve trains. Think of a spring board diver. He gets additional height by jumping in synch with the board’s natural frequency. In his case, he wants additional height, or lofting off the board. In the case of the valve train you do not want lofting. Investigating how the flexibility of the valve train interacts with the valve train’s natural frequency is impossible to calculate without a sophisticated valve train simulation.
Spintron has gotten some good press lately, and deservedly so. Several race teams use them for testing and developing valve trains. It is a good tool, letting you spin the cam and valve train at high RPM. It requires a VERY large electric motor (25-75 HP, requiring 40-155 amps at 440 VAC). It is also quite expensive, $50K to $100K. Click here for their website www.spintron.com
However, there are things even the $100,000 Spintron does not simulate. A major one is the high cylinder pressure working to keep the exhaust valve closed during valve opening. Take a 1.9″ diameter valve head working against, say, 700 psi when it first starts to open. That’s almost 2000 lbs of extra force required to open the exhaust valve. And on blown engines, that cylinder pressure at exhaust valve opening will be much higher. The extra force to overcome cylinder pressure changes the exhaust valve train dynamics and forces significantly.
Bottom line is that both the Spintron and Engine Analyzer Pro’s valve train simulation are useful tools to understand and develop high RPM valve trains. However, the Engine Analzer Pro is available at 1/100 the price ($469 vs $50,000), requires no special 440 VAC wiring or engine/engine mods/prototype parts, and actually does some things better.
Some of the pics in this blog are taken from our Engine Analyzer Pro’s user’s manual, Example 4.2 starting on page 167. This manual is a wealth of information, not only on how our Engine Analzyer Pro works, but on basic race engine operation. Here’s a link to it if you want to read more http://www.performancetrends.com/PDFs/EAPMan4.pdf