a buddy of mine recently got his 8 tuned with his fp green turbo. i lent him my old turbosmart bov to pull past 25 psi. well sure enough our local tuning shop did a leak down test, ran up to 28 psi so we were good to go. tuned the car at 410 whp at 25psi. anyway we went over to the track this weekend and found out that even with nothing changed for some reason 1,2,3 boost would hit 25psi and drop back down to 20 psi but 4 would hold 25psi just fine.

we were left scratching our heads. thinking it could be the bov? wondering if anyone can chimmy in on this and figure it out.

i dont have the logs from the tune but it was on a 4th gear pull so that wouldnt help. mind you the bov was completely recirculated.

i'd like some insight what it could be. he doesnt have the upgraded wastegate either its just the standard wastegate thats included with the turbo.

 

you have more load in 4th.

 

i believe its the same as well.

update: yesterday we installed a stock IX bov and this time boost went from
25 to 21 on 1st
25 to 22 on 2nd
25 to 23 on 3rd
and held 4th at 25

the whole time ive been looking up about the turbosmart bov it seems like its a strong bov but i cant figure out why it wasnt holding boost when it was 100% recirculated.

anyway the boost dropping im sure has to do with the stock internal wastegate the fp green turbos come with. anyway if anyone is looking for a strong bov and considered the turbosmart for a decent hold. look somewhere else.

btw, all the bolts were tight while testing