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The Details
This list only serves as a guideline for the parts that
need to be changed but I have detailed why those components need to be
replaced as well as given a general guideline for the conversion itself
below. In addition to this, I would strongly suggest having a Nissan service
manual for your Z as it will be one of your best tools in this process.
Fuel Pump: The fuel pumps are different between the two different
models. They appear the same from the outside, however, the pump mechanism
in the TT has a higher capacity than the NA. The only way to tell the
difference between the two is the fact that the NA has a number "14"
cast into the backplate whereas the TT has a "16" in it. This
definately needs to be replaced when you convert your Z. The NA pump will
be able to keep up with the demand up to a certain point, but I found
that was short lived and the pump could not maintain proper pressure as
the fuel demand rose with RPM.
Oil Pump: The oil pumps used on the NA engine ARE different than
on the TT. The TT pump is significantly larger to prodive ample pressure/flow
for the turbos and oil cooler system. I built my TT engine from an NA
engine and did not change the oil pump out because I was under the impression
that the pumps were actually the same.. I pulled the engine the weekend
of 8/24/02 to change the oil pump and connectoing rod bearings. Oil pressure
before the change was ~50-60psi max and now the needle comes up to 90psi
at high RPM. It is definately at least 10psi per 1000RPM, and better than
that on the top end.
Cooling: The electric fan on the TT is a two speed unit and the
NA is a single speed unit. This really can be overlooked. But, the radiators
are different. The TT radiator mounts are different than the NA mounts
and there are no holes with nice welded nuts to just make this a "bolt
on" conversion.. You will have to drill holes to make this work.
Same goes with the AC condenser. These are two of the easiest parts of
the conversion though. The intake plumbing also has mounting points which
will need to be fabricated. As parts are being installed, sheetmetal and
a torch will come in handy.
ECU: Well folks, breaking news here, the NA and TT ECU are essentially
interchangeable. You cannot use a 5pseed ECU in an automatic application,
but you can go the other way. The NA ECU is missing a few resistors and
transistors which are used to complete the circuitry for the boost control
solenoids. What this means is that you either need to use a boost controller
or connect pin 25 to pin 50 of the ECU (ground). A stage 3 TT ECU can
be used with the NA harness as well but it will lack this function. I
have on a few occasions soldered in these additional circuits and was
able to convert a 5 speed to automatic and an NA ECU to TT spec.
The manual transmission: There are some minor differences between
the NA and TT transmission.The TT flywheel is ~4mm larger in diameter
so in order to have the correct starter gear to flywheel gear clearance,
you need to use (1) 2.5mm washers (one on each bolt) to space the starter
away from the transmission bell. If you have access to a machine shop,
or would just rather have it done right, a plate could be machined to
take up the slack.. However, I have been using washers in my setup without
any issues. Since my Z is manual shift, I dont have any information on
the automatic trannies. You'll have to do some homework to figure that
out.
Oil cooler: This is highly recommended. The stock unit is kinda
small/expensive and finding a used stock cooler for a respectable price
just didn't come to me. There are a ton of units out there that can be
had for cheap and the hardware to use an aftermarket unit isnt expensive
either. The TT(only) oil filter bracket has a pipe to attach the outflow
hose to the cooler and the return pipe from the cooler connects to the
oil pan. I picked up an oil cooler from a local junkyard that came off
of a 4 cylinder Volvo turbo 'something'. I didn't pay attention to the
model of the car, it just had this really nicely sized cooler in it and
I pulled it. I paid ten bucks for the thing! I bought 8mm fuel hose and
a few hose clamps to hook everything up and it works beautifully.
Fuel Injectors: On pre 1994 models the fuel rails on both the
TT andthe NA are the same. You can install TT injectors into the NA fuel
rail if you a building an NA engine to TT spec. On1994 and up models,
the injectors are from different manufacturers and the fuel rails are
different between the NA and TT. In order to put TT injectors on an NA
engine (for 1994+ models), you will need the TT fuel rail and you will
have to grind the lower plenum a bit to allow the rail to fit. Do this
when the lower plenum is off of the engine as aluminum dust could cause
problems if it gets into the valves or cylinders. Because there are no
fuelrail->lower plenum seals for putting a TT fuel rail on an NA lower
plenum (for '94+models only), you will have to get some o-rings to put
on the end of the injector cups on the fuel rail and also remove the plastic
fuel rail spacers to get a proper fit and good seal on the NA lower plenum.
This was one of the trickier steps in the process because there isn't
any room for error when grinding the lower plenum, fitting the orings,
and bolting it all in. If one of them didn't seal, the only time to find
out is once everything is in the car and you hear obvious hissing. :)
Not a good time to find out.
Turbos: Turbo oil and coolant lines are a bit tricky to figure
out, but it's simple one you know their routes and the associated hardware
that is used(isn't it always?). The two metal (20mm) coolant pipes on
the back of the engine provide coolant to the heater core for the AC system.
The pipe coming directly off the passenger side head is where the coolant
flows outward from the cylinder head. The other pipe that runs between
the heads to the water pump is the suction side. Both of the two heater
core pipes have smaller (9.5mm) pipes that come off of them, two per pipe.
These normally supply coolant to the throttle bodies. Run your turbo coolant
lines directly from the small pipe fittings and eliminate the throttle
body cooling circuit. The TB coolant circuit heats up the throttle bodies,
which will heat up your intake charge and lower power as well as raise
the probability of detonation. Just bypass it and be happy you did. It
will not be detrimental to engine life at all, and it could be argued
that it actually has a positive effect on engine longevity.
The oil supply for the turbos comes right off the side of the block and
there are two blocking bolts to remove to gain access to the pressurized
gallies. The driver side turbo oil supply galley is on the side of the
block near the front edge and down near the oil pan edge. The passenger
oil supply is near the back of the block in the middle (vertically). These
blocking bolts need to be removed when the engine is disassembled and
the gallies need to be thoroughly flushed to remove any oil coke or metal
shavings.
Boost & BOVs: Setting up the wastegate actuator lines is pretty
straightforward and this should be easy to figure out, especially if you
are going to use a boost controller. The instructions on how to set it
up are going to be in the installation manual. :-P The same goes for BOVs
if you plan to use them. I have heard of people running as much as 20psi
on stock recircs without leak, and they may even go higher. This same
person replaced them with BOVs when he put bigger turbos/ICs and upped
the boost but I believe that they will still hold beyond that. Manifold
pressure/vacuum is directed to the BOVs control diaphragm and under high
boost, that pressure actually works to hold the recirc closed so I think
they're good all the way up to whatever you want to run. However, if you
want to run a bleeder system using welding tips/jets, all you need to
do is buy the hose, a few 'T' connectors from AutoZone and some welding
tips from Home Depot. Run a line from the boost hose connector to the
wastegate actuator with as boost jet installed in the hose on the boost
pipe side. A few inches back you need to install a "T" connector
that has (2)1/4" pipe inlets and one 1/8" inlet. The two 1/4"
inlets need to connect the line you have installed. The other 1/8"
connector needs to connect to a rubber hose leading down to the metal
pipe just before the turbo. There is a nipple in there to attach it to.
You need to do this on both sides. Using a 0.035" welding tip in
this configuration produced 14.7psi of boost in my Z.
Oxygen Sensors: O2 sensors are the same, dont worry about changing
them out.
Pistons & Oil Jets: The under piston oil jets are different
between the two models. The NA jets aim toward the center/bottom of the
piston whereas the TT jets aim toward the side/bottom of the piston. They
actually shoot oil right into one of the holes that leads to a galley
just under the piston crown for cooling purposes. See picture above of
pistons for a better idea of this. If you use aftermarket forged pistons,
it is adviseable to use the NA squirters as none of the aftermarket pistons
have the cooling channel and the TT jets will unevenly cool the piston.
This could be an issue with forged pistons as they expand/contract much
more because of their higher grain density. Variations in temperatures
across the piston crowns will cause the piston to become oddly shaped
and cause cylinder/piston wear or even worse, the ring lands will pinch
the rings and you'll lose compression and the engine will quit.
Exhaust: Midpipes must be replaced. Mid pipes are the section
of the exhaust system just after the precats. They also include the main
catalytic converters which cannot be removed, only punched out.
Clutch: The TT uses a clutch booster to ease clutch actuation
which is very similar to the brake booster and located just to the lower
right of the brake booster. Although it is not necessary to put this in
your NA for the conversion, it will make shifting a bit easier on an aftermarket
clutch. Aftermarket clutches use (2500psi+ pressure plate), so it may
be adviseable to acquire the booster components and install it when you
do the clutch. You may find it very difficult to shift without it. I have
installed a TT clutch in my conversion and I am not using the booster.
It is holding the power very well and believe it or not, the clutch actually
feels identical to when I had the NA clutch in there. Go figure. The RPS
pressure plate I am using (sport series) offers 15% greater clamping force
too.q
Super HICAS: Forget the Super HICAS - its lame anyway. :-) Get
yourself a nice set of shocks and coilover springs so you get the benefit
of having an adjustable suspension system. Add a set of sway bars and
replace your suspension bushings and you'll be well set.
The Conversion
You will need to prepare yourself and your work area for
about two full days of wrenching. A car lift is ideal, but that's not
something that everyone has access to. A floorjack and a good reliable
set of jackstands will be in order. An engine hoist and associated chaining
is necessary. All of the other 'general' tools I wont mention here, just
grab the tool you need and go at it.
There is an order to follow in doing the conversion, most
of it is obvious, but as for my conversion there were a few things that
I wish I had done in different order to ease the process. Here's my notes..
1. Remove trans
2. Remove engine
3. Remove Air Filter, Airflow Sensor, 'Y' tube, Fascia, and undercarriage
skirting
4. Remove AC condenser, then AC lines, and charcoal canister. Plug up
hoses going to charcoal canister. Remove metal piping for CC.
5. Install intake plumbing and make supporting brackets
6. Prefit intercoolers
7. Make IC brackets and weld to unibody
8. Attach ICs and tighten hose clamps
9. Install TT AC lines, followed by condenser.
10. Make oil cooler brackets and weld to core support. Mount oil cooler.
11. Attach new fascia and install undercarriage skirting
12. Hold off on installing air filter/MAS/Y-tube until oil cooler hoses
are attached
13. Inspect engine bay. Look for areas of leakage from the
steering rack and note.
14. Clean the engine bay. I used a pressure washer and engine degreaser
to blast everything clean.
15. Replace steering rack bushings and tighten all fittings believe to
be a source of leakage, or replace connectors/brackets/seals as necessary.
16. Inspect wiring harness for signs of wear, cracking, burning. Replace/repair
as necessary. Clean ALL connectors and prelube with dielectric grease.
17. Look for signs of corrosion. Areas of vulnerability are in the battery
area and down near the precats. The rust in these areas should be brushed
off with a wire brush, treated with phosphoric acid and painted. A high-temp
ceramic based paint would be the best thing to use here.
18. Be sure to inspect the engine mounts thoroughly if you are re-using
a set. They tend to come apart at the junction between the metal and the
rubber. If there is any sign of seperation, do not reuse them.
19. By all means, replace the hoses and belts for everything while you
have the engine out. Going back to replace all of them afterward is a
huge waste of time.
You are now ready to install the engine and connect wiring
harness, install radiator, intake pipes, exhaust system, and drivetrain.
The oil cooler hoses need to be cut and installed using
appropriate hose clamps. I routed the hoses as close to the unibody framing
member as I could so as to keep it away from the engine, belts, accessories,
etc. Anything that could damage the hose was avoided.
Of course, you'll need to add all of the fluids and connect
all of the fuel lines, etc etc etc, but at this point you are ready to
start her up. Happy boosting!
*If there is anything that I have left out or if there is
something that you would like to add or comment on, please email
me with the details!
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