Power Levels
Some companies advertise stage 1, 2, and 3 for turbo kits. This isn't very fair in my opinion, because z32 guys get 5+ levels. So I'm just going to make up new stages, based on what builds I've seen.
Stage .5:
Turbo kit, usually junkyard style, smic, and rrfpr.
Parts needed:
Turbo, manifold, blow off valve (BOV), wastegate (unless you have an actuated turbo), smic, fuel pump, rrfpr.
Estimated power levels: It's hit or miss. I've seen 180rwhp @ 6-8psi, and I've seen 230rwhp @ 8psi.
Stage 1:
Basic turbo kit. FMax and XSEngineering both sell their kits with rrfprs, which irks me, because they rarely include a severely-needed fuel pump. Any well pieced together kit will make the same power levels.
Parts needed: Everything from above, but with better parts, and a FMIC.
Claimed power levels: 220rwhp @ 6psi to 240rwhp at 8psi. Depends on the kit.
Stage 2:
This is where people usually go next.
Parts needed:
3" Exhaust. Aftermarket head filter, usually s-afc + 370cc injectors
Estimated power levels: 240 @ 6psi to 260 @ 8psi.
Stage 3.
About 3 in 10 go this far with their turbo kits.
Parts needed:
This is always a tuned ecu, usually z32 or cobra maf, 370cc injectors or larger, aiming for 3" turbo-back exhaust, so larger downpipe, testpipe or high-flow catalytic convertor. Here grip and traction matter.
Estimated power levels: This is a grey area, as there are so many variables. 370cc injectors top out at 275rwhp or so. As does the stock maf. Ignition system is recommended for 300hp+, because the boost tends to blow out the spark.
Here's what I'll say: Limits: 370cc injectors = 270rwhp @ 8-10psi. 50# injectors = 350rwhp @ 15-18psi. At 325rwhp or so, I'd think about moving to stage 4.
Stage 4:
Time for more boost. But with the factory piston ring lands so prone to shattering, they've got to go. While you're there, there are some optional parts to replace.
Required: Forged pistons. While you're in the motor, think about replacing (optional): Rods, rod and main bearings, oil pump, timing components, all gaskets and seals (front and rear main seals, ect). Servicing the tranny and replacing tranny seals should also be done. (I didn't do that, and now have a leaking rear tranny seal
)
Power limits: This is rare air. Encroaching on the 400hp club. 72# injectors will be good to 440rwhp or so. Tuning becomes a major factor for the exact horsepower limits. 50# injectors should be thrown away, because they're still limiting you to 350rwhp.
Stage 5:
The whole damn thing. You've got boost. Lots of it. On your built bottom end. But there's gotta be a top end, too. So fix it.
Parts needed: Cams. Swap in some cams, and you'll feel like it's a different car. You'll need some valve springs and retainers, because a built bottom end and cams will open up a 7200-7500rpm redline, and I'm sure you'd want to use it. While you're there, think about valves, and a valve job. Deburr and polish the head (mild port and polish job). Port match the head for the intake and exhaust manifolds.
Cautions: Do not do a major port and polish. This has been blamed for many high powered motors, from BoostedS14 on here, to Chris May's 2 motors in the 438rwhp s14 that was featured in SCC.
*When you swap cams, your car will go from not wanting to approach redline to bouncing off the rev limiter. Hehehe*
Power levels: You still care about these? It's in the 11 second range. Same power, less boost.
Stage 5+:
This isn't really a stage, but wallet permitting, there are many more things you can do. From standalone engine management and throwing out the maf to creating your own intake manifold, or extrude honing the stockie. Imagination and wallet are the limits. You could have even worked with JWT to develop a 96# injector program (now in progress) for sick, sick power levels. 96# injectors should be good to 575+, I haven't done the calculations on it.
Now. This is for refrence only. Don't bitch when you spend $4k and make 10 or 20hp less than "estimated." Alot depends on tuning, and the condition of your motor. There are also the Nissan Freak motors, which produce 30hp more than they should on any setup. Look at the enjuku SR, 393 hp on a t3/4, while no other SR has done over 330 on that kit.
-Jeff