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I owned a 77 Accord that had the CVCC (compound vortex controlled combustion) engine.
It used two intake passages, with 2 intake valves and 1 exhaust.
The smaller passageway was a completely separate induction circuit from the main passage. The carburetor had a dedicated circuit for the small passageway and there was a prechamber in the cylinder head, somewhat similar to a diesel.
The small circuit prechamber ran at an AF mix of 12 to 1, while the main circuit ran at 18to 1. The smaller circuit was initially ignited by the spark plug, then the flame front transitioned to the leaner main circuit.
Not very powerful engines but they did not require catalytic converters to pass then current emissions regulations.
The VX is very different. It Has 4 valves per cylinder and VTEC-E, with port fuel injection. Lean burn is accomplished by only slightly opening one of the intake vales under 2500 RPM, which produces a high swirl action and better distribution of the fuel and air mix. Combined with a special Oxygen sensor (very expensive) it can run at mixtures as high as 22-24 to 1 at low revs and low throttle positions.
I could not feel any transition in the 77 Accord because there wasn't really a transition to feel. In the VX it is obvious, when the transition occurs. Its almost like an old 4 barrel when the secondaries opened up.
I also owned an 84 CRX 1.5 that I bought new. Serial # 1018 made in June of 83. I think it was also a CVCC design. Without even trying to get good mileage I averaged 44 MPG for the 50k miles I drove that car.
As emissions tightened the CVCC was replaced with fuel injection a couple of years after that 84 model.
regards
Mech
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