I am currently rebuilding my heads and I could use the collective experience of the gurus out there..


The OEM V8 JDM STI SAVCS heads, being shimmless buckets are good for 8200k rpm right out of the box.


That is with the following OEM spring rates..


49lbs @36mm SET

130 lbs @ 24.65 LOAD





But at what boost levels ?


I have heard of people cramming up to 30 psi into the stock heads with no ill effect..



Furthermore there are some mathematical gurus who have calculated that given that 31 psi boost is the upper limit and after that this will overcome the OEM spring pressure of 49lbs and open the valve.


My heads, have done 150k,and came out of a stock GDB from Japan.



The machine shop tells me have been boost floating- evidenced by the back of the exhaust valve becoming concave and the valve spring seats showing wear as well.


This is true.. but the valve tips don't look bashed, and there is very little wear on the intake valves, which being heavier should boost float first right?


Also we measured the spring tensions.. It was within the factory spec of 49+-3lbs.


Also this was a ex japan GDB with a stock turbo and ECU.. so over revving couldnt have been an issue.





I asked them if something else could be causing this.. he tells me that with his 30 years of experience that the valves have been boost floating..



So im a bit conflicted ..




Got it rex runs 30 psi wit these heads using the OEM valve springs..
Plenty of others also attest to this.
But are they getting boost float and don't realise it?


If we tear down the engines will we see the same "subclinical' valve seat wear as my heads?


Bottom line is the following..


Should i get new OEM valve springs or should I upgrade..


I am going to use new stock oem valves and looking to push the engine to around 28-30 psi..



thanks in advance?