Designing a Turbokit for the 2JZ-GE is not that difficult. There are a
few things to keep in mind when deciding what you want to do. The
biggest decision is whether you want to build yourself a kit or order a
pre-built one.
Buying vs. Building
Building your own kit is very rewarding and you will learn more about
your engine than you thought possible. The price is a good bit cheaper
as you can source your own parts off ebay and buy used items off of
other owners. This isnt always the case however as there are some very
inexpensive kits coming to market. 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. If you
purchased used parts, they don't come with warranty and will not last
as long and a lot of times they just arent as good of a quality as new
stuff is.
Parts in a Typical NA-T kit
***Turbo manifold: There are log and header types, headers flow for
more power, but spool slower. Cast iron or stainless tubular are the
best bets.
***Wastegate: The bigger you go, the more control you have and less
chances for spikes and creep. At least a 35mm wastegate is suggested.
Many kits are running 38 and 40mm gates, which is fine, but 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 for
you. 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.
***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: There is a wide range to select from. You should pick this based on your power goals.
***Front Mount Intercooler (FMIC): 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.
***Exhaust system: A 3 inch downpipe and 3" exhaust system! At least 3
inches all the way back if you can. Turbos need flow, so 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
***Head Gasket: The stock 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). I suggest going with a 2mm-2.5mm headgasket.
***Fuel injectors: The 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.
***Fuel Management: A method of controlling the 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. The Stock AFM when utilizing a SAFC to run
bigger injectors can only be setup to run "decently" on 440cc injectors
or so... any larger and you're pulling too much fuel. IT WILL NOT RUN
550cc INJECTORS. You will need a much better piggyback or standalone to
accomplish this. When modifying the airflow signal, you are also
causing the ECU to advance the timing, because at lower airflow levels
the ECU advances timing. So the ECU THINKS its in a certain part of the
map when it really isnt. Guess what too much advance does? BOOM! Buh
bye motor! Best fix for smaller injectors such as 440s and 550s is to
run the V8 AFM along with a simple fuel controller (or a more complex
one such as the emanage). Can be picked up off any 1uz Lexus from 91-95
(SC4, LS4). This AFM is calibrated for larger injectors (roughly 420cc
or so) so the adjustment is much less.
***Oil feed/drain lines: 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
