Possible turbo 318 build
for a bare minimum Single Turbo for your 318....ok...on a Penny Pinching Budget...maybe....and I'll tell you WHY.
IF you have 8:1 Compression....you might be able to squeeze 20 psi with that turbo and make 480-500 at the wheels....but if you will open that ebay link/window and look that those specifications.....that turbo is a T3 twin scroll exhaust housing (another words-divided exhaust inlet) with a 2.5"discharge....but the Kicker for the Flow Limit is the Compressor INDUCER...57mm is 3mm LESS than I recommended for a minimum.
You can only stuff so much air through a certain sized hole.....and as you begin to play with exhaust driven compressors...you will very quickly discover the limits of small diameter piping....because it all boils down to VOLUME...not PRESSURE.
60mm is 2.36 inches and 2.5" is 63.5mm
This is semi important.
A 2.5" 18ga exhaust tube will flow enough air for roughly 330 hp, (and I am NOT going to go into the math of interior pipe volume or fluid and thermal dynamics) so suffice to say a turbo WHILE not compressing air needs to be able to flow the amount of air the Driver Engine makes at peak hp Naturally Aspirated.....in your case lets call it a Mild 318...and peg the NA peak hp around 350 crank hp.....the Base size for your Turbo - Compressor Inducer should be around 2.5" and the exhaust should be sized just a tad BIGGER for thermal expansion flow capability....so around 65mm Turbine Exducer.....because at 1x atmospheric pressure, the exhaust pressure also increases roughly 14.7 psi, then flow is doubled, so there it is, a properly designed/setup turbocharger system will yield 100% more power than the driver engine made NA.
The A/R number most turbos list is the Ratio of the size of the Exhaust Inlet to the turbine exducer size, and is generally given to help determine spool-up characteristics....the smaller the A/R the lower in the RPM band full boost can be achieved, the larger the A/R the higher in the RPM band full boost will be available. You can run a T3 exhaust housing...but I highly recommend a T4 housing if you stick with a Single Turbo App.
For a 5.2L engine with a RPM Ceiling of 6500-7000 rpm, I would suggest a .96, or even a 1.06, and would expect full boost around 3500-3700 rpm.
I would suggest a SINGLE Tial 44mm wastegate.
The price/quality of the turbo you settle with will and can only be decided by and funded by you....but I personally would start with a quality piece and not a Ebay Special.
Ohh and NOT ALL THOSE Turbos' cost $1200.00 When you say GT or Dual Ball Bearing you can expect the price to double over the cost of a regular thrust bearing type turbocharger.
I have called them up personally, NUMEROUS times and ordered a custom spec'd turbo and had it to my door for less than $800...Quality is not Cheap my friend.
Forced Induction is one of those things that will hammer home that message.