Can someone break down these turbo specs for me

[POS carb]

This is for a supposed T3/T4 turbo


2.36" INLET DIAMETER
2" OUTLET
WET FLOATING BEARINGS
1/8 NPT OIL INLET
T3 / T4 FOOTPRINT OK !!
FITS T3 AND T3/T4 MANIFOLDS
SPECS:
. 42 A/R COMPRESSOR
.48 A/R TURBINE

======O R======

3" INLET DIAMETER
2" OUTLET
WET FLOATING BALL BEARINGS
1/8 NPT OIL INLET
T3 / T4 FOOTPRINT OK !!
SPECS:
.57T COMPRESSOR WHEEL
.50 A/R COMPRESSOR
.63 A/R TURBINE


Which spec determines how soon it spools and what specs determine the engine size andor useful RPM range?

>nooB<

[NXRacer]

This is for a supposed T3/T4 turbo

Which spec determines how soon it spools and what specs determine the engine size andor useful RPM range?

>nooB<

SPECS:
.42 A/R COMPRESSOR
.48 A/R TURBINE

======O R======

SPECS:
.57T COMPRESSOR WHEEL
.50 A/R COMPRESSOR
.63 A/R TURBINE

the compressor wheel and turbine determine how fast it'll spool and how much boost it can create. The bigger the number, the more boost it can make, but it takes longer to create that boost.

[Justin86]

prob be best to go with the smaller specs for a good street turbo, but some maps would be helpful.

[AccordEpicenter]

the first one sounds like a straight T3 42/48. Itll be fully boosted by 3200-3500 rpm. The T3/T4 will be fully boosted by about 4000rpm or so on our engines. The bigger compressor side adds a negligable amount of lag, but the real way to tell when its gonna spool is look at the exhaust housing and turbine stage (both of these are stage I turbines) but the .48 exhaust turbine does not flow as much as the .63 turbine, so the .63 will spool up later and be a little less responsive, but the upside is youll get a bigger top end pull. The .48 will produce boost sooner and be less laggy at the trade off of less top end power. I run the .63 on my stock motor and i have no compaints.


EDIT: Oh yea, if youre running low boost (id say 9psi or below) the .42/.48 is just fine. For bigger boost/more power, the t3/t4 is a better choice. Its all about how much power you want to make

[Justin86]

yea and Sean was running the basic T3 with the .48 turbine and .42 compressor and he was making very nice power with just a built head. He was able to push it up to 15PSI but it is the perfect turbo for a stock bottom end and low boost like AccordEpicenter said.