VTEC-E stand for VTEC-ECONOMY, meaning, its slow and is a piece of garbage.
VTEC and I-VTEC are the newer (most efficient) kinds of VTEC.
Actually, I read the e in vtec-e is for enhanced performance (as in performance and fuel efficiency) from Haynes. This is a common misconception.
In vtec-e there is one large lobe on the camshaft and one very small lobe. Under low rpm cruising the engine practically runs with 12 valves (4 intake valves and 8 exhaust). When vtec-e engages the large lobe rocker and small lobe rocker are linked together via a hydraulic rod. Then both valves open the large amount and the small camshaft lobe doesn't touch it's rocker. The large valve lobe on camshaft is actually slightly larger than the middle lobe on regular vtec (meaning the intake flow should be better on d16y5s). I attribute the lower performance (115hp) of the HX compared to the EX to the backpressure difference in the exhaust manifold and ecu mapping. The HX (D16Y5) is less fuel efficient than the VX (d15z1) but has 20 more hp. This is due to the EX intake system with EGR and 3.75 gearing.
The 5-wire lean burn O2 sensor and the 3.25 gear ratio of the VX tranny do much more for fuel efficiency than vtec-e.
The d15z1 was designed for low end torque. It has a smaller intake valve, intake runners, throttle body. This gives the engine more low rpm torque and power but overall chokes the engine limiting its overall output. It is not always about the maximum amount of horsepower. It is more about power in the rpm band where you can use it. This engine was designed for fuel effiecency.
That being said, I have been looking for a d15z1 to swap into my HX. ( I have a '68 Charger for performance and my Civic is for fuel efficiency because civics where engineered to be fuel efficent. )
PMed.
