I've heard rummours that tuners have been saying that the ST170 head won't take more than around 12psi due to valve float.

Now this is plausable, but the Americans who have far more experience with turboing this engine than us don't seem to have come across this problem.

Any thoughts?

Rick.

 

Surely that an issue with valve springs? Maybe they are talking about the stock ones? The yanks probably uprate them.

JAmes.

 

im sure ive heard of st170 heads flowing to 300 as standard? (see how i stated heard)

 

a standard black top zetec head will flow over 330 easy with just a set of up rated springs.

 

what about the st170 heads? saying that im on the look out for a compleat 2.0 black top head if you no of any??

 

ive got one here and a full set of st170 springs

 

To clarify, the yanks don't uprate the valve springs - that's the point.

 

Americans don't really have a great record of turbocharging engines in an elegant manner, so I wouldn't worry too much about what you see over there.

The bottom line is the standard valve springs on any zetec head will cause lifters to jack up at anything over low to medium power. No point in arsing about - uprate them!

 

bang on the money and straight to the point as usual

 

So what are the options? Area Six are over £400 for their double spring package which seems a little excessive.

Rick

 

there single spring kit is only £250 and good for 20psi@7k about 25psi@6500rpm and they come with the same retainers as the double spring kit so if you ever want to upgrade you just need the extra springs

 

If the standard springs allow float then yeah thats got to be adressed.
Surly fitting high lb springs on hydraulics is gonna have them pumping out at the rpm your talking about?
I'm not clued up on the 170 heads, can they not take solid lifters and double springs on OE cams?

 

They are solid lifters as std.

 

Aren't they direct acting followers?

JAmes

 

try looking at some audi,s mate as they have smaller assistor springs sat inside the proper valve springs

cost effective if on a budget perhaps