noob boost question

[bozwell]

so i recently swapped a 1Z from a passat into my 90 golf (my first TDI ) and ive been reading thru the performance upgrade section of the FAQ. it says in the FAQ not to exceed 18psi of boost at sea level but it really doesnt explain why. is it a physical limitation of the engine or will the shaft speed of the turbo reach an unsafe level? id imagine a performance chip would increase boost more than 3psi so can someone please enlighten me?

 

[Evgeniy K.]

this is limit of your stock turbo.
Limit of stock engine is 25psi as far as i know.

 

[cog]

yeah 18 psi is whats recomended for a re-mapped stock turbo , they run at 15 psi in stock form . 18 psi is considered the max sustainable boost for a long lasting turbo . it also depends on the spikes .

 

[bozwell]

so at 25psi do the head bolts start to stretch or the rods come out the block?

 

[bozwell]

anyone?

 

[cog]

no the psi limit is down to your turbo size and what it can handle for instance the stock vnt 15 max safe boost is around 18psi with spikes upto 21 psi. the vnt 17vb is around 22-24 psi max and the 17/22 hybrid will sustain around 26psi
but anything over 24psi and you will need bigger intercooler and bigger hoses to handle the extra boost otherwise you get pipes leaking and blowing off under pressure .