Currently I have a td04 15G kit on my EF. the turbo will be rebuilt by next summer and I was wondering if anyone knew if I could use the center section of the td05 18G from the turbos meant for the DOHC from greddy.

Ultimately I'd like to keep the quick spooling feature of the small td04 15G but would like the potential of more power like that of the 18G.

I'm confused as to what it is I would need to get more power out of the turbo. is it just the compressor wheel? is it the housings? are the wheel sizes of the 15G and 18G the same or different?

I was told I could just port the housings and get a bigger compressor wheel to get where I want to....is that really all I need?

I'm really lost.

Currently the turbo is fine and spools incredibly fast:
starts spooling @ 2500ish, 5psi @ 3100ish, 13PSI by 4100ish
stock z6
stock greddy DP and only a 60mm I.D. exhaust

however I would like to eventually get up to around the 250-300whp level while still retaining the quick spooling of a small turbo.

immediate plans are:
custom 3" I.D. turbo back
retune @ lower PSI but staying around 190ish whp....till the block is built

after I build up the block and head plans are:
vitara build w/ TT rods(or comparable)
ported/polished head w/ full valvetrain
zex59300 cam(or comparable)
get 250-300whp on lowest boost possible while retaining a long power curve

 

I'm not sure about mixing and matching the parts, I don't know if it would be worth the trouble either.
The 18G should spool plenty fast on the Z6 and should get you at least close to 300WHP. Maybe check out a GT28 also. Or, you can hop on the Borg Warner bandwagon and see what they have that is comparable.

 

Yeah I figured I'd ask. I'd really prefer to keep the same turbo while getting an upgrade so I don't have to change anything else in my setup

 

any other input