I have been contemplating a similar project for my girlfriends focus....I have a few comments.
First, why go through the expense of having custom cams ground? There are a wide variety of z-tech cams out there. In fairness, I'm not sure where the variable cam timing thing comes into play in terms of interchangability, but I don't see why you couldn't just put in a focus motor and computer if it becomes a problem, the sensors and wiring should be very close to identical.
Second, I don't know if stroking it is a good idea. Being a small displacement engine, you are looking for RPMS to get substantial horsepower gains...longer stroke plus higher rpms equals greater piston velocity. That will not increase engine durability. Also, I'm not sure how strong the stock crank is to begin with, a substantial increase in horsepower plus a decrease in journal diameters due to offset grinding could result in a big boom. Also, the displacement increase will probably be negligable on such a small engine, .2 liters would probably be the max. Also, does anyone make undersized rod bearings??? On a side note to this train of thought, I did see a forged z-tech crank for sale on line somewhere for $2400.
Third, don't shave the head, this will mess up your belt length for driving the cams. All compression changes should be done with pistons. Custom pistons aren't that expensive, and you seem willing to spend the money anyway.
Fourth, look into cylinder wall thickness before overboring. I am personally going to shy away from it because I'm planning on keeping the compression down in my project so I can turbo it later. I want some meat there if there will be boost involved.
Fifth, titanium rods. I also saw z-tech titanium rods for sale on the internet. They were also $2400. Half the weight and twice the strenght of steel rods. Less reciprocating weight results in more power to the wheels. Following this logic, an aluminum flywheel should also be considered.
Sixth, after re-camming the motor, and preparing for the inevitable higher RPM operation, you will probably want a new ring gear for the tranny. Something lower will get you out of the low RPMs (where you won't be making much power) quicker. The SVT focus six speed might be a nice idea because the motor could potentially be very "peaky" and more variety in gear selection would help stay in the power band.
Seventh, consider having the intakes acid dipped to increase the volume of air available in the intake at any given time. You may come out ahead with this approach in high RPM use since you will lose some port velocity (low end torque) but the greater volume will make more power available at high rpms. Also, look into SVT focus induction, it is revised considerably from the contour 4 cyl.
Eigth, I like the idea of titanium valne springs, but in fairness it probably isn't really necessary. I would opt for titanium wrist pins first to decrease reciprocating weight.
Let me know what you think.
-FD
Last edited by Forbidden Doughnut; 10/30/02 12:34 AM.
