Hey Guys
I have a 89 r32 gtst rb20det (motor originally from a r32 gts4)
i'm wondering what sort of power ill be looking at with my build (first build i have done)
right so its a rb20det with a t3t4 low mount turbo with a custom built 3 inch exhaust, straight from the back of the turbo, look off the old 2.5 inch dump pipe, leading to 1 muffler and a short twin boso.
Red Jacket coils (similar to spit fires)
38mm external waste gate with 1.0 bar spring
440cc injectors with factory fuel rail and a walbro 500hp fuel pump
front facing plenum with the factory throttle body with a large front mount and 3 inch pipes.
z32 air flow meter
288 kelford cams cam shaft and hks cam gears and cam belt
factory drive shaft (chop and weld) with a SR20det gearbox.
i think thats about it. thanks for taking a look.

I had an RB20det with:

T3/T04E Turbonetics turbo
TIAl 38mm w/g
Bosch 044 intank pump
440 injectors
Spearco crappy front mount
Nismo afpr
Splitfire coils
Tomei 256/256 cams
stock internals/stock head/stock intake manifold
eBay exhaust manifold with Axis 3 inch complete exhaust
Power FC D Jetro with MAP

Made 380 ish rwhp at 19 psi.

However, I highly suggest keeping the boost under 19 or have a pretty good tune as stock RB20 pistons love to melt. I also recommend head studs as I did as well as maybe re enforcing the bottom end with ACL bearings. I would also lose the stock intake manifold and the head stock is extrememly limited. I would, if you stay stock, only go around 14 psi and stay under 340 rwhp for good, reliable power. At 14 psi, my car made 336 rwhp and it ran like a freaking dream. I would not cheap out on ecu management and fuel delivery. I had a bad ecu that created lean spots that ultimately led to the death of all 6 pistons melting. If you plan to truly build the motor, boost the hell out of it and have a secondary plan set up or in motion. If you want more power, but don't want a huge build later, stay at 14 psi and under 340 rwhp and it should run all day long with no problems.

Also, what forward facing facing plenum are you using?
Did you factor in wiring in the resistor pack to hold the 440 injectors from a GTR or are they 440 made for the RB20?
What valve springs are you using? Any head work aside from bigger cams? Any reason for going that big?

Like I said the stock RB20 head is stupid restrictive. The factory exhaust ports have this lump in them that creates a huge flow problem coupled with very tiny ports. The head stock just flows poorly. Pay attention for fuel and spark and just have a good tuner tinker with it. Like I said, RB20 pistons love to melt.

Also, why the SR20 transmission? The RB20/KA/SR transmissions are virtually the exact same. As far as I know, the SR is no stronger than the RB transmission. If you want strength, get an RB25 or Z32 turbo transmission. Those are much stronger than the RB20/SR20/KA transmission. The only problem with an RB25 tranny is that it is electric speedo and the RB20 is cable driven, so you either have no speedo/odo or you get an adapter that converts the electric to cable. They sell them but I forgot who makes them. I think they are like 30-40 bucks?

i dont know exact name of the plenum, but the guy im going to get to tune my car highly recommends them, and does not sell them, so that kind of showed me he was not just trying to make a sale.
oh yeah head has been ported and polished.
reason for going so big with the cams was purely because the new head i brought, had them already, so thought why not get rid of the factory ones.
im only aiming for 320hp but if i can get more on a safe tune at 14psi i will be happy.
lol i knew some one would ask about the gear box! bit un-usual i guess, but i had gone through 3 rb20det gear boxes, and was becoming harder and harder to find! so i got the sr box, and omg i cant believe how it runs! improved my car so much, with the rb20det box i was not even able to reach limiter while drifting, but now i can take it to 3rd comfortably (this was when all that i had done to my car was coils and spark plugs and fuel pump)
yup got all the wiring done for the injectors, fitted the resistor, but am now wondering if i want to get a Link G4 ecu, i wont need the resistor if i do, or a afm. but its alot of money.

Do not go cheap. RB engines do not do cheap. Save the extra cash and do it right or you will be doing it again with greater costs. I had a Nistune chip in my ecu and because of this, my ecu died and ended up creating damage to the motor that showed up later. Do not go cheap.

320 rwhp is easily attainable as long as the tuner knows their stuff. Do you have a wideband? If not, that is a great investment and actually helps the tuner a bit. Gives him a general idea quickly how things are. It is not exact, but it is close enough to save you in the long run.

I have my original RB20 trans from 1989. It had made countless pulls on the dyno and a few road course sections. You may want to invest in an RB25 trans if you plan to bang it around. Just throwing that out there.

the motor will live at 14 psi, if tuned correctly, the rest of its life. The factory boost settings are .7 BAR which is 10 psi I think? Going up 4 should be no issue. The factory ceramic turbo can handle 14, but not for long.

Again, its either cheap and quick, or pricy and reliable.

well so far i have not gone cheap at all, have spent 14k nzd. and pln on spending at least another 4-5k on the engine alone.
wideband is the air - fuel ratio sensor or something right? i dont have one, hate the look of guages cluttering the car, and i have looked into getting a nismo 25 dog box

Wow, 14K? I am building my RB20 for less than that. Bored/stroked/forged/ported/polished/bigger turbo....

I bid you good luck man! I hope it turns out how you plan.