Designing a Turbokit for the 2JZ-GE
There are a few things to keep in mind when deciding what you want to do. The biggest decision RIGHT NOW is whether you want to build a DIY kit or order a pre-built one from a reputable shop.
Going the DIY
is very rewarding and you will learn more about your engine than you thought possible. I personally went this route TWICE on my first two setups on my SC300. But I had the typical problems.
-The Price is a good bit cheaper. Face it, you can source your own parts off ebay, used items off of SupraForums and Clublexus classifieds, etc and probably build a kit for much cheaper IF you get everything. This isnt always the case
-The installation is a bit more difficult since you're putting together parts that werent necessarily designed for one another and may require some fabrication
-Used parts dont last as long and a lot of times they just arent as good of a quality as new stuff is (new stuff is ALWAYS coming out for the GE car nowadays).
Buying a Kit
is much simpler and easier to follow. You will still learn a lot about your motor if you install your kit yourself and still have the oppurtunity to purchase some used parts if you can find good deals, etc. Buying a kit you KNOW that it will work correctly if its a reputable shop such as BoostLogic, Sound Performance, PHR, Dave H, etc. People have already done them, posted their results and their problems so you can be ready for it when its your turn. You can purchase a turbo kit, fuel kit, aem kit, and be done with it and have a monster on your hands. They literally come with everything you need... being from the other side, I can tell you that this is an immense PLUS. It doesnt quite sound like it... but having done it twice, this is the way I will do it a 3rd time.
Parts in a Typical Basic NA-T kit (note this is not everything you need)
Turbo manifold (there are log and header types, headers flow for more power, but spool slower)
Wastegate (bigger you go, the more control you have and less chances for spikes and creep)
Downpipe (connects to your exhaust)
Intake pipe (connects from your turbo inlet to your filter or AFM)
Oil feed and drain lines (feed and drain oil to/from the turbo)
Turbocharger (large varieties of these, this is what makes boost!)
In the basic kit you usually run directly off the wastegate spring. Most kits keep you running on the stock compression levels (10:1 remember?) in the first "stage" or two, until you get serious about power anyways. This results in quicker spoolup and better off-boost response but you cannot run as much boost without risking serious damage to your motor.
-10:1 compression limits you to around 7-8psi without fiddling with your ignition timing (stock timing has a big "spike" of advance around 4000-4500rpms that will cause detonation if running more than 8-9psi and the base timing is not retarded 3-4 degrees)
-stock injectors will also limit you powerwise. I've seen several setups make OVER 400whp on the stock fuel setup (upgraded fuel pump) but its still best to upgrade them (and with a way to control them too -- SAFC, emanage, MAP ECU, AEM standalone, etc)... generally I wouldnt go over 350whp with the stock 330s.
-intercooler options, some kits come with some dont, most of the lower-priced ones dont and you are left to fend for yourself in the intercooler arena... you NEED one to run more than 5 or 6psi reliably
What you REALLY need for a well balanced kit
-strong turbo manifold, either a strong cast unit or a strong (IE 321 Stainless Steel) tubular header manifold... Dave H's manifold runs via Weld Els and it is VERY strong and beefy. His manifold is more of a hybrid, not really a log and not really a header.
-turbocharger to suit your powerband preferences (a later discussion perhaps?). Most people go with a T04E or PTE style turbo that makes around 400whp at 10psi of boost.
EDIT: Thanks for suprapunk pointing out something: If you are building your own kit: Ensure that your exhaust turbine lines up with your manifold
Like make sure its a T4 hotside and a T4 flange on the manifold, and make sure you have the correct hotside outlet as well to mate to your downpipe (v-band, on-center, etc)
-35mm wastegate, Tial or HKS brands are good stuff. Many kits are running 38 and 40mm gates, which is fine, they cost more. Depending on how much power you'll be making with your turbo, you need to decide what to run unless a kit-maker already picks one.
-fuel and a method of controlling that fuel to supply enough for your power needs. On more basic setups I recommend the Emanage blue. Affordable and can tune your car very nicely. Most basic kits can make good power with MKIII Supra Turbo injectors. They are also top feed (but low impedance, need resistor box or inline resistors) and denso style but flow 440cc instead of 330. The Lexus V8 AFM modification is affordable and can make the 440s easily tunable with a simple fuel controller.
-a FRONT MOUNT INTERCOOLER. Do it once, do it right. The sidemount jobs cannot compare with the Front mounts other than being harder to see. You can pick up good quality units off ebay for under $300 these days.
-A 3 inch downpipe and 3" exhaust system! At least 3 inches all the way back if you can. Turbos need FLOW, give them a bigger exhaust and they will spool faster and give you MORE POWER.
-GOOD spark plugs and good conditioned ignition system (get a new rotor and cap for your distributor pronto!). NGK 3330s and NGK 6097s are both great plugs, they are pregapped at .031 which is perfect for turbo applications under 19-20psi of boost
-Oil feed/drain lines properly sized. Typical setup is -3 or -4 AN feed with a -10 (no smaller) drain line. Garret turbos require much less oil than most people think; and dumping high pressure (60psi+) oil into it and then having a small return line blows the oil seals on the turbo very quickly. You want NO flow resistance on the return line. You can do this by having a BIG return line like a -10 or use a oil-line restrictor (can pick them up at atpturbo.com). IF you buy a premade kit that comes with a oil-line kit then don't fret, its already been tested and setup with the turbo you'll be running from the kit.
Keep in MIND!!! That all of this is how to get power reliably out of the MOTOR. The transmission and the rear end are completely different subjects. Your stock clutch WILL NOT withstand more than 300whp and last for very long. Your stock transmission WILL NOT WITHSTAND more than 400-450whp for very long and driven hard (your mileage may vary).
Autos are very different from the stock 5-speeds. Do your research on driveline modifications!
