MattD wrote:kevp wrote:The Valves in the 1.8 zetec are the same as the 2.0, as are the cams (after-market). So you could fit the existing head to a 2.0l bottom for easy/cheap power/torque increase.
When I was looking into zetec tweaking, pretty sure that Paul Dunnell told me a 1.8 head couldnt go onto the 2.0 bottom end. I had one in the shed (still do if anyone wants it) & asked if he could mod this to suit, whilst I still had the unmodifed 2ltr one running in the car. A polite but firm NO was the answer. Something to do with piston height & combustion chamber size. As the 1.8 bore is smaller (80.6 vs 84.

i would presume it raises the CR beyond acceptable limits.
Oops missed the obvious - wrong bore size 1.8 - 2.0. Dont know about compression - sorry.
To see the difference in silver/blacktop. Black top has external Water Pump & an engine mount on the front (pulley end) of engine. The oil filter is direct on the block. The heads are interchangeable but the cam belt requires a new idler pulley to mounted or run an Alfa cam belt (cant remember the size, but I do have the info or which way round ie silver to black or black to silver top)
Rob, my silvertop has solid lifters so will rev higher than the hydraulic head. I have a friend with triple springs on solid lifters in his solver top. Will rev way past 9000. He does autocross (I think).
Another option is to turbo-charge, which due to the pig iron is very reliable & strong. Just by keeping the boost low you can get 300bhp & run the engine forever. I have seen 700+ on a zetec, but need to rebuild often, (thats every 2 years for my mileage).
So my current opinion is - if you need to replace the engine with a zetec unit. It may as well be the ST170 as the valves & ports are the largest without modifications & the bottom end is the strongest in its standard set up. Just port the manifold to suit. Dont know about the oil pick up though in respect to the shortened sump. It may just be a straight swap though like the earlier zetecs.