I just swaped my T78 Greddy turbo with a brand new HKS T04 z ,huge power above 5500rpm but i expected the turbo to kick in sooner .Since the turbo is ball bearing i thought that would spool faster but i thing the T78 kicked in 700-1000rpms lower. Another thing ,comparing to the T78 the T04 turbo produces a massive amount of temprature, my engine bay is like an oven.Any one uses the T04z turbo ? any info will be much appreciated !

 

pm "riceracer" he's the resident guru on the TO4Z.

 

Are you sure you don't have an exhaust leak between the turbo and the manifold?

 

i dont thing so ,i would have heard it.

 

Reason I said that, is you said its laggy and hotter on the hood. Both don't make any sense.

 

a leak could explain both,i ll check it again

 

Depends on your tuning, switch turbos you are going to have to make changes, you could be running really rich causing extra heat....also did your A/R of your turbine housing go smaller? I believe the A/R of the T78 is 1.00 or if you went smaller a/r, its having a harder time getting the heat out of the engine and more back pressure.....just some thoughts

 

The a/r is the same ( 1.00) ,and we just tryed out the turbo on low boost (up to0.8- 1.0 psi)we didnt complete tuning but the difference was noticeble
beside any posible problem (tuning or other) i thing that we agree that the turbo should behave different!

 

do small leaks cause that big of a difference in lag? say a HKS cast manifold (on a FC) is leaking from the manifold to wastegate.
not alot, but enough to feel it with your hand right next to it.