Honda CR-X Blows Flywheel: What Happens when VTEC and Turbo Kick In at the Same Time

After watching the video below, many would be tempted to say that the two being brought together act like an overdose for your engine, but the matter is much more complex than that.

First of all, there are two possible scenarios here. Judging by that launch the CR-X performed, it's obvious that the output of the four-banger was seriously upgraded, but perhaps the clutch & flywheel package was left in stock form, which might have caused the power wave to disintegrate the flywheel.

Moreover, this could be a lightened flywheel, as racers do this in order to lower inertia. People sometimes get greedy (no, not Greddy) and tend to skip/ignore the calculus part, which leads to a flywheels that's too fragile for its job. Leaving this poor CR-X aside, it's time to talk about what happens when you treat your engine with both these mechanical goodies.

Turbo and VTEC never actually kick in at the same time

For those readers who don't know what VTEC means exactly, in the case of the older models like the one we have here, this describes Honda's two stage variable valve timing.

The camshaft basically has two sets of lobes per valve. One is optimized for low rpm, while the other for high rpm. At a designated rpm point, the engine switches to the second profile, while the ignition timing is advanced.Now the intake valves are opened up for a longer period of time, allowing extra oxygen and fuel to enter the cylinder.

The idea is that the VTEC rpm is an entirely different matter to the revs where the turbo is engaged. To be more specific, on a turbocharged engine, VTEC is usually tuned to step in earlier, as the high-rpm profile helps decrease the turbo spool time. Besides reducing turbo lag, the move also minimizes the stress on the engine, avoiding a sudden jump in air pressure inside the cylinders.

This is where the fine tuning part... kicks in, as keeping the valves open for longer can cause the compressed air to escape the combustion chamber under certain circumstances. Thus, you need to determine the correct point for engaging VTEC while considering the turbocharger's action.