thsmrtone1 said:
a stock vtec-e is meant for one thing only... economy. when below activation, only one valve is open, causing the air/fuel mixture to mix more effectively (creates a swirl in the chamber)... when the vtec engages, the second valve opens, however, because the motor is built for economy and economy only, the horsepower gained when the VTEC is engaged is still less than that of a non-vtec motor... the only exception for this is the Y5 and the d17a2... other than that there is no vtec-e engine that is worth anything but good gas milage...
as far as VTEC vs VTEC-e goes, there is no vtec-e with more horsepower than any VTEC motor
Bense(a member on here) got me into this stuff...
The obd1 vtec-e(fficiency) motor is the d15z1. It comes in the 92-95 vx hatchback in the USA. This cylinder head has some undesireable attributes: small valves, small ports, MILD cam... And some attributes that are interesting: near cloverleafed chamber, roller rockers...
I purchased a d15z1 head in an attempt to find out about all this vtec-e stuff, only to find out it's main casting is nearly worthless, from a high performance standpoint. In an attempt to salvage the money spent on the cylinder head, I started comparing rocker assemblies, and the d15z1 assembly fits the d16z6 head. This means, you can have the EFFICIENCY of vtec-e, on a higher flowing head. Looks good, now, huh.
Of course, my hopes were dashed with the z1 head, so I acquired a obd2 d16y5 head(civic HX). This head has the same head casting as the d16y8 head, and it also has roller rockers. It has the same, larger, valves as the d16y8, d16z6, d16y7, and d16b5(natural gas), and has the same ports as the d16y8(as it's the same p2j casting). It also has the quench pads on both intake and exhaust sides that will raise compression, and heighten resistance to detonation with the right pistons/clearance.
Utilizing the y5 head, on top of another d16 block with decent compression, should yeild decent/interesting results. The hard part is tuning the thing for the mileage that it should be able to make, and the timing map will be a nightmare. But I have confidence; I've tuned a boosted obd2 prelude with type-s pistons(11:1) with a p28. This may sound easy, but let me tell you, it took some thinking/research. Hopefuly I can do the same with the motor in my sig. All the parts are on the way...
The Y5 head is pretty nice. Correct the obvious flaws, and you've got some potential...
-josh-