351CJ said:
I also believe that the 4 valve heads will pretty much fade away. If you look at the 3V #'s on 87 octane gas 300 HP / 315 lb ft and then add about 5% if the compression ratio was raised to 10.5:1 for 91 Octane you have 315 HP & 330 lb ft which is essentially the same as the 2004 Mach 1 4 valve engine. Now throw into the mix that the 3 valve engine is lower cost to manufacture, smaller in size and lighter in weight, where does that leave the 4 valve heads?
QUOTE]
...what leads you to believe that 3v heads with VCT are cheaper to manufacture than the 4v heads? i would think VCT would be more expensive than the extra valve/cyl but i'm just guessing.
wouldn't it be cool if the put VCT on the current 4v mach1....can you say power under the curve?
-steve
I have it on pretty good authority that VCT costs about $200 / engine (Ford V type), but should come down as volume goes up. The problem with the 4V is that it has 2 more cams, 8 more valves, 8 more valve springs, 8 more valve seals, 8 more valve retainers, 50 more lb, of aluminum, more oil passages to machine, more cam journals to machine, more cam retainer blocks and on and on and on. The 4V, 4 cam engines are considerable more expensive to manufacture than the 2 cam engines.
The 3V heads breath just about as good as the 4V heads do and they are physically smaller and lighter. The ONLY real advantage of the DOHC heads are that they could be implimented with more sophisticated VCT that allows separate cam timing variations between the intake and exhuast cams.
If Ford's future was in the 4V / 4 CAM engines, wouldn't they have come out with VCT on the 4 CAM / 4.6L engine first? Belive me, in the future you will only see the 4 CAM engines on Premium vehicles and special performance models.