Will a set of forged rods and pistons from a normal black top fit...high comp ones, or even a silver top( they would be matched pairs ie silver top rods and silvertop pistons)

Been offered some wiseco ones I think off a mate for a favourable rate.

Cheers

 

A black top hi comp piston with a ST170 head will give much higher comp ratio, the problem is not knowing what your Comp ratio will be, which is extremely important.
If your going forced induction then you want to be lowering your compression not making it higher, if your looking to rev higher and keep it N/A then i would just change the rods for now.

 

High comp for n/a yes. Didn't realise high comp black top pistons and st170 head = v. High compression. Will measure the comp ratio when i build it if i can get hold of them. Wanted them as might get a very good offer and though they'd be stronger.

 

Not if you end up machining the piston crown to drop the compression.
For example a 11.0:1 High compression black top piston would give you roughly a compression ratio of 11.5:1 with a SVT head you could fit a thicker cometic gasket but is would have to be more than 0.040 in thickness to bring the compression down low enough
ST170 standard pistons will take a fair amount of RPM, its the rod bolts that are the first weak point followed by the Oil pump, a N/A engine needs to rev to produce BHP the achillies heel of this engine is the oil pump,it is generally a time bomb after 7600rpm due to harmonic problems causing nose flex in the crank which shatters the pump gears, so only solution is to go dry sump but there is no off the shelf kit for the engine in standard configuration so you will have to maufacture bespoke parts to fit the kit and this will cost £1000+