[ElementSR]

What is ZETEC?

ZETEC is the name of the motor, similar to Chevy's ECOTEC, and Honda's B16, H22 series motor names. The ZETEC engine features something similar to VTEC called VCT. See 'What is VCT' for more info about it.


What is the difference between the ZX2 ZETEC and the ZX3 Zetec?
While both motors share the ZETEC name and appear similar to the untrained eye, they are different. Both bottoms end are the same, while the heads of both motors are different. The ZX2 posses VCT on the exhaust side, while the ZX3 (with the exception of the SVT focus) do not have VCT. The SVT focus has VCT on the intake cam. Transmition are also different. The ZX2 MTX uses a G5M tranny, while the ZX3 MTX uses a MTX-75. The bolt pattern for the tranny mounting is almost the same on the ZX2 and the ZX2. But there is one bottom bolt that does not line up. You will have to modify the frame rail, and get some new axles (contact http://www.zxtuner.com for axles) but the MTX-75 is a possible swap.


What is VCT??

VCT stands for Variable Cam Timing. It is controlled by oil pressure, basically to control valve overlap and help control emissions and help out with gas mileage. With VCT off (at idle for example) the exhaust cam is fully advanced, with minimum overlap. As VCT becomes active at some rpms the cams are partly retarded (with more cam overlap) increasing upper rpm power. Under some conditions the cams are fully retarded 60 (cam) degrees resulting in EGR like behavior. At 60 degrees, the cams are retarded too much to make optimum power. If you eliminate the VCT you need to adjust the cams on a dyno for the best retardation to optimize power. This best peak HP setting will result in more static overlap than with the VCT active and net less low end torque. Nevertheless if you are after peak HP, eliminating the VCT is a good way to do.
Ford uses the VCT to retard the exhaust cam as much as 60 (crank) degrees. This results in a lot of overlap and some exhaust gas recirculation. Most of the time the amount of cam retard is too great to benefit high end power.


What is the difference between the ZX2 VCT and the ZX3 Zetec?

ZX2 has the VCT on the exhaust side. The ZX3 except for the SVT focus doesn not have it. The SVT has it on the Intake side.

One side effect of VCT is that the ZX2 uses more aggressive cams than the ZX3 and still meets emissions requirements.

ZX2 Intake: 214 deg @ 0.050, 0.366" lift
ZX3 Intake: 206 deg @ 0.050, 0.353" lift

ZX2 exhaust: 211 deg @ 0.050, 0.338" lift
ZX3 exhaust: 205 deg @ 0.050, 0.342" lift

If you need to meet emissions testing, the VCT engine will allow you to run more aggressive cams. If you don't need to meet emissions testing, then the VCT has little value.


What other cars have VCT??

99 and '00 Zetecs in Contour and Mystique models have exhaust VCT.

All Zetecs in ZX2 and Cougars have exhaust VCT.

No other Zetec engines (Focus, Escape, pre-'99 Contour) have exhaust VCT.

SVT Focus has intake VCT....

That should just about cover all the North America Ford and Mercury cars with Zetecs...


When was the first ZETEC??

"The first Zetec dates back to 1992, when it first appeared in Escorts (1.6 and 1.8 and Fiestas (1.. The 16v head was developed by Yamaha and based on a strengthened CVH block. The Mondeo was the only vehicle to use the 2.0L derivative of the engine, which appeared in 1993. The early engine is identified by looking on the cam cover - on the front left hand side it will read 'DOHC 16V' "

More info:
http://www.fiestaprojects.com/zetec.html

[ZX3TUNR]

Very good info..

[hemi]

Nice work man. I never knew and was afraid to ask.

[ElementSR]

lol thought i should clarify see we are not much different.

[boost til'bust]

just something to clear up.

The cam timing isnt really "controlled" by oil pressure, its controlled by the PCM which controls a solenoid, and that solenoid uses oil pressure to move the cam gear.

[ZX3TUNING]

funny, i have been saying this for years!


also, VCT and Vtec are comepletely different.

vct uses a standard cam profile and adjusts timing on the entire cam.

vtec uses a 2 lobe cam and special rocker assembly
there are 2 seperate profiles on each cam, one for standard driving and a bigger profile for higher rpm driving. the bigger profile has a much higher lift, duration and overlap than the smaller profile which allows for better breathing at higher rpms in a NA application.
Vtec uses a computer controlled oil solenoid that energizes the rocker assembly to lock allowing the bigger profile to work the valves, this happens at a specified rpm(on most vtec honda/acuras @ around 5500rpm). the rocker assemble has 3 rockers per pair of valves, 2 of which are for the smaller lobes that directly activate the valves as a standard DOHC motor works, the thrid rocker is for the bigger lobe which sits directly inbetween the 2 smaller lobes for each cyl. normally the center rocker assembly for the bigger lobe is "floating" and the big lobe does nothing but move the "floating" rocker while the smaller lobes directly control the valves via their respective rockers. once the engine hits that magic rpm the solenoid locks the middle rocker assembly to the others via oil pressure and both valves per cyl are now being actuated by the bigger lobe as the smaller ones are no longer in contact with their rockers.

VCT is nothing like this.

VCT was originally designed by ford as a way of meeting the new(at the time) CARB requirements for new cars. the idea behind it was always for emmissions. a boost in power at varrious amounts out cam retard was just an added benifit.

although i'm sure rob will have something to say about that. :D

good post though