One of the best ways to make horsepower is with high engine RPM. Being a key factor in how much horsepower an engine can make, many manufacturers and builders of gasoline-driven engines are always looking for ways to increase an engine’s operating RPM.
Of course, all of the components inside said engine must be up to the task of holding together under all the additional strain. Whereas yesterday’s engineers relied heavily on slide rules and physics, today’s motor-geeks have several more tools at their disposal – one of them, happens to be called a “SpinTron.”
Designed by engineers, for engineers, a SpinTron allows them to test engines and engine parts without having to hook up those pesky wires and hoses. Basically, the machine drives the engine instead of internal combustion. Interestingly, while there isn’t any exhaust noise, it does help illustrate how noisy an engine can be at speed, even when it isn’t “running.” And, as is the case here, much of the SpinTron’s testing is to evaluate the durability and stability of the valvetrain, so our engine doesn’t even have pistons or connecting rods wiggling around inside.
The engine in this example, a 358-inch, LS-based V8, is used by Ben Strader of EFI University to help sort out and illustrate various valvetrain components. This particular engine has a COMP Cams solid-roller camshaft deep inside, which measures out to 0.820-inch lift. It uses a set of T&D aluminum shaft rockers topside to transfer the lifter’s wishes to the valve’s stem. Pushing back against those wishes is a set of COMP 7245 Dual-conical valve springs installed at a height of 1.995-inches with about 200-205lbs of seat pressure. According to Ben, the springs are “nested” so they don’t interfere with each other and he explains that they must have somewhere between 50-100 runs on them already.
So, what does it sound like when an engine that isn’t running runs up over 10,000 rpm? The revs plateau at around 3,500 rpm, and then the electric motor that spins the engine’s crankshaft is given a full feeding of ions. The engine revs quickly, and almost instantly goes into bumble-bee mode. It holds this glass-shattering pitch for just a few seconds, and then the fun is over. There isn’t any dramatic finale to the video, simply that the valvetrain did what it was asked to do, at a speed that it would be rarely asked to do it. Check out this video below of a valve and spring on a SpinTron, doing what you DON’T want it to do!
Ben explains that if they ever intend on spinning the engine that high on its own power, they need to go into the engine and work their magic to provide enough airflow for the engine to even be able to pump that much air at speed. As it stands, the noisy little engine with no exhaust note has proven to have a quite reliable valvetrain installed. And once all the good stuff goes inside, it should make for quite the fun powerhouse. Check out EFI University’s Facebook page for more information on this engine and many of the other instructional tidbits they offer almost daily.