Hi Guys

We are lifiting the evo 9 head after a few dyno passes at 48 to 50 psi of boost on arps 625s head studs stock size, using a 67mm turbo.

The space around the haed studs nuts are quite small to have a larger head stud/nut combo installed while still using kipling valve springs,

Do you know any tuner/vendor selling around/machining the evo 9 mivec heads for larger studs? one that would also do the blocks wire ringing?

thanks for the advance

 

I ran into a similar issue when assembled my 4g64 block using 12mm studs…..the clearance between the head stud nuts and the valve spring seats were very tight if not interfering. I ended up grinding ~2mm off the total outside diameter of the nuts to allow for fitment. Let me know if you need some pics!
Btw I also ended up enlarging the head bores to allow for the larger studs.

 

lifting head is not correct diagnosis. you are flexing the head. stronger studs wont help. turn the boost down or except high horsepower runs are meant for ten seconds of happiness.