ZDriver.com - How to make the N/A Faster?? swap mass merge thread

I see that some of you have questions about the conversion, so here goes...
ENGINE
1. The blocks are the same. They both have oil squirters that direct oil towards the underside of the piston, but they point at different angles. The oil squirters on the TT direct oil straight into a off center hole on the underside of the TT piston, which leads to a hollow area inside the top of the TT piston. The NA ones just direct the oil towards the middle of the underside of the piston which has no passages inside. They blocks have all of the same oil passages. Two passages are plugged with a bolt on the NA block (one on each outside face that feed the turbos on a TT). The TT has two oil passages plugged inside where the oil filter bracket mounts, the NA has two small check valves in this location. They are plugged in the TT providing more pressure so that the oil will go through the lines to the oil cooler, which returns back to the oil pan. There are check valves on the inside of the TT oil filter bracket where the oil filter screws on, but none on the NA The purpose of these check valves is if the oil filter somehow becomes clogged or collapses that oil will still circulate.
2. The crankshaft is the same.
3. Connecting rods ARE the same!! (Same Nissan part #)
4. Piston rings, and Crankshaft (main) bearings are the same. The rod bearings are the same size but the TT ones are a different alloy (kelmet).
5. Of course the pistons are different because of lower compression ratio in the TT, 8.5:1 in respect to 10.5:1 on the NA. The internal structure of the pistons is also different, the TT ones have a hollow ring inside the top that fills with oil for better cooling and a thicker dome towards the center. Oil pumps are different. They mount the same and are the same internally except for the spring for the pressure valve in the TT one is tighter, so it produces more needed pressure to circulate oil to the turbos and cooler. You can actually just change the spring to the tighter one.
6.Oil filter bracket on a TT is different (longer) because it has an outlet that accommodates the hose going to the oil cooler. There is a spring loaded valve in the bracket that will not let the oil circulate to the cooler unless there is sufficient pressure. And then there are the spring loaded ball check valves that let oil bypass the oil filter if there is a problem, these are in the block on an NA. Oil filters are all the same.
7. Cams, Lifters, and valve springs ARE the same (90-93)(same Nissan Part #) The Auto TT has different intake cams (lower lift) but the intake cams on the 5 speed TT, NA, and auto NA are the same. The different intake cams in the auto TT along with the slightly smaller exhaust housings on the turbos results in 20 less HP in the auto TT (it was detuned to make the transmission last longer). All the exhaust cams are the same. The 94-95 cams were different than the 90-93 but just like the earlier ones they are all the same except for the intake cams on the auto TT. The 96 cams were ALL the same.
8. The valves are all the same size. But the exhaust valves on a TT are made from a stronger alloy (iconel)
9. Nissan claims the bare heads are different but I no longer believe it. I used to think the thickness was different but after some measurements I believe they are the same and have been using them interchangeably (just making sure the exhaust valves are the stronger TT ones) or just using all replacement valves which are usually made to TT specs, with no problems. We use different spark plugs on the NA and TT, but we see them used backwards and every way in between a lot. The TT ones we use are NGK PFR6B-11B which are slightly longer that the NA PFR6G-11. The longer plug is "colder" which helps with preventing detonation at higher boost levels.
10. The oil pan is different because the TT one has 2 tubes protruding on the sides where the oil return hoses for the turbos mount and another one for the hose returning from the oil cooler.
11.The turbo engine obviously has a few different accessories and systems to accommodate the turbos. The exhaust manifolds on the TT are much shorter than the NA ones, which go all the way down and tie into the exhaust section including the catalytic converters. The turbos are oil lubricated and water cooled. So there are oil and water, supply and return lines everywhere on a TT motor.
12. The throttle bodies are the same size but the passenger side one is different on a TT simply because one of the water lines attached to the bottom of it has a junction in it to feed water to one turbo. But we usually do away with all that nonsense with the water lines under the plenum running to the TB's in our warm climate. We just run water to and from the metal hoses on the back of the motor going to and from the heater core.
13. The upper and lower intake manifolds are the same TT and NA 90-92. The newer ones are
different from the earlier ones. They made the change to the new style injectors, lower plenum, and the intake port on the heads in 93 for the NA but not till 95 on the TT. So lower plenum and heads would be different on 93-94 NA and TT's. The upper plenums changed just a small bit in 94 when the angle that the flange of one of the EGR tubes bolts on to the plenum rotated about 30 degrees. Just enough stuff to make interchanges a pain.
14. Motor mounts are the same, but I have a secret on that. I guess I'll let it out if you've read this far although I have made some money because of it. The convertible motor mounts are the same but substantially cheaper for some reason. Motor mounts are broken into almost every time we pull a motor, so we go through lot of them and have saved $.
15. Head gaskets have a different part # but appear to be the same we use all TT ones because they are cheaper also (another secret).
16. Water pump, PCV valves, exhaust, intake, plenum, valve cover gaskets, seals, Timing belt, thermostat all the same.

ELECTRICAL
1. Nissan claimed the TT coil packs were different a couple years ago and charged a lot more for them. I checked them and found that they were the same and now Nissan lists them as the same.
I guess they got caught on that one.
2. Of course the ECU is the same, (You will have to reprogram it though). Transmission computer on the automatics is different, other than that there are no control units that must be changed.
3. The Main engine (EFI) harness is different also, but a NA harness will work in an TT, you just will not have the connections for the boost control solenoids which you don't need anyway if you have a boost controller. I don't recommend wasting your time with the conversion if you are to cheap to buy a boost controller. If necessary we have an easy way to remove the engine harness without removing hardly anything inside the car. The is an aluminum bracket bolted right inside the firewall that makes the engine harness a difficult to change. The bracket is bolted in behind the heater core and AC evaporator so it is hard to remove from the inside. We take a pneumatic reciprocating saw and cut the passenger side of the bracket into from inside the engine bay and then with some prying the bracket pivots around on one bolt and moves out of your way.
4. If converting NA --> TT, I would leave the interior harness and gauge cluster alone. They will work with the TT setup. Get a stand alone boost gauge because the stock one sux. You would be insane to add the Hicas system or stock electronic adjustable suspension to a NA so you will not need the TT interior harness. I would leave all major wiring harnesses alone when doing a conversion.
5. MAF, PTU, TPS, IAA, AIV, EGR, O2 sensors, Detonation sensor, Coolant temperature sensor are all the same.
6. The electrical AC Condenser fan is different on a TT. The motor has three wires (2 speed) going to it as opposed to two (one speed) on the NA. But you can get by with the NA one on a conversion. The mechanical fan is the same but the fan clutch is different. The TT's have a yellow dot on the front and are tighter than the NA's with an orange dot.
7. The starters are all the same.

OTHER DRIVETRAIN
1. If converting most people would keep the NA rear differential, because a lot of TT owners switch to it anyway. It has a lower ratio (4.08 compared to 3.67) that will decrease your top speed but enhance take off. Plus converting differentials is not easy. You must change the entire rear subframe because the differentials mount completely different. You would also have to change the halfshafts, which have a six bolt flange on the TT where they bolt to the diff (compared to five on the NA) and the ends are larger diameter where the slines go into the hubs. So the hubs are different. Since the TT has the Hicas tie rods in the rear there is an additional suspension arm on the NA to make up for the lack of support there. Because of the way these bolt up differently to the knuckle, the knuckles are different also, unless you press a ball joint out and somehow press a hollow bushing back in.
2. As long as you keep the NA rear diff, the NA driveshaft will work. The TT driveshaft will not work with an NA diff or vice versa. The TT driveshaft has a CV joint at the end where it bolts to the differential and larger U-joints. There are 6 different driveshafts for the Z: TT auto and 5sp, 2s NA auto and 5sp, and 4s NA auto and 5 sp. The stock drivesahft is a 2 piece so you can mix and match combinations and usually come up with something that will work what ever you are trying, because they will all bolt together in the middle. The center support bearings will work interchangably although they are listed differently and there is a little issue about shimming one.
We buy all new TT ones because they are cheaper. But the best idea is probably just to go with a one piece unit anyway.
3. The NA and TT have the same 5 speed transmission model #, same splines on input and output shafts, etc. and the housings are the same except for one small difference. The spot where the starter mounts on the bellhousing on the TT is machined a little differently so that the starter will properly engage the slightly larger diameter flywheel and so that the flywheel teeth won't scrape the inside of the bellhousing. You can use an NA 5 speed in a TT but you just have to shim the starter out a little with some flat washers and sometimes grind a little out of the inside of the bellhousing so the TT flywheel will fit inside.
If trying to use a TT trans in an NA you would either have to grind down where the starter mounts so that it could engage the smaller NA flywheel or just use the TT flywheel, which could be used with only a TT clutch. I have heard that some of the internals in the TT 5 sp are stronger. I have used them interchangeably without problems. The only thing left on a Z32 we have yet to do is rebuild a 5 sp transmission so I am not sure.
The automatic transmission is different for a TT, but the NA auto would still fit in place behind the TT engine. Although, they are different lengths and you would have to use the corresponding driveshaft. Both autos are geared virtually the same but the TT one is built for heavier duty.
4. The speed sensor gear in the transmission is different, different size for NA and TT because of the different ratios in the diff. So if you are using a NA diff you need a NA speed sensor gear. The gear is different auto and 5 sp also.
5. The TT clutch has a larger contact face, a stronger pressure plate and a slightly larger diameter flywheel. You can use a TT flywheel in an NA by shimming out the starter but can?t use a NA flywheel in a TT without cutting down the spot where the starter mounts to the TT transmission. You have to use a TT clutch assembly with a TT flywheel and the same with NA because of the way the pressure plate bolts to the flywheel. The TT's also included a clutch booster assembly because of the stronger pressure plate. The clutch pedal and master cylinder were different because of a vacuum assisted clutch booster inside the firewall. The booster included two plastic tanks for vacuum storage also, one under the drivers fender and one under the clutch master cylinder and a network of hoses connecting them all. Because of the clutch booster the clutch pedal and master cylinder are different between NA and TT but all the slave cylinders are the same. You don't have to add this setup when doing a conversion (a lot of trouble) the clutch pedal will just be stiff but its not unbearable in my opinion.
OTHER
1. The Radiator and AC Condenser are MUCH different. They are much narrower on a TT so the intercooler piping can go around each side. The front lower core support is also different (but can be modified to work with a little cutting and welding) because the TT radiator and condenser mount farther down into it because they are taller to make up for the difference in width. There are some differences in the AC lines also. The upper radiator hose on the TT is also different but the lower one is the same. We often go to home depot and buy some chrome drain pipe to replace the bottom section of the radiator hose which can collapse. We just splice it in with some clamps, better that paying for the Stillen solid hose and easier to work with when removing/installing the radiator.
2. When swapping the NA rear diff into the TT the best option is to do away with all the Hicas lines, solenoid, reservoir, pws pump, etc. The NA pws pump is smaller and provides less drag on the motor. Plus the TT pump has two chambers, one for the front and one for the rear. So if you eliminate the HICAS what do you want the fluid pumping back there for? Like with the return fittings Stillen supplies for there rip-off HICAS elimination bar. You also don't want to just disconnect all of that and still run a TT pump, because it requires lubrication in the rear chamber provided by the fluid. So if converting you would stay with the NA pws pump. The mounting brackets on the block for the PWS pump are different for the TT and NA as well as the length of the bolt that the pump pivots on.
3.The front steering rack looks and fits exactly the same but they have different gear ratios inside providing for more turn with less steering wheel travel in the NA which doesn't have the rear wheels to assist. But it isn't something to change in a conversion.
4.The rest of the front suspension is the same, except for shocks and springs. The TT shocks are the 2 way adjustable units and the TT springs are more progressive, but in a conversion I would just go with aftermarket performance units on both. The TT swaybars are also stiffer but no big deal, just go aftermarket performance with that also at your convenience.
5. The calipers and rotors are all the same size except for in 90 when the NA calipers supported a slightly thinner 26 mm widen rotor. There was not enough cooling capacity in that rotor so all the later NA's and all TT's had 30mm wide rotors. The calipers were all aluminum until 93 when they went to cast iron.
6. The TT alternator is higher output (90A vs 80A) but they are interchangeable. I don?t think putting a TT alternator on an NA is a bad idea.
7. The AC Compressors are the same for corresponding year models.
8. The TT has all of the intake/turbo/intercooler piping, intercoolers, and recirculation valves. On an NA air goes from the intake to the throttle bodies, for a TT we go in the intake to the turbos back up front to the intercoolers and then to the throttle bodies (big difference). This can be one of the most difficult things to put on a NA, because all the brakets that attach it to the frame on the TT do not exist on the NA you just have to get it in there and support it the best you can. It isn?t easy to find used and is one of the main reasons I recommend buying an entire wrecked TT for parts if you are trying to convert from an NA. When I have complete sets of plumbing for a TT I sell them together for around $500 (minus intercoolers and turbos) which is only a fraction of what they cost new.
9.The exhaust is all different for the TT (every single section is different in some way). Although if you get the J-spec downpipes (which are stock in Japan in the place of our precats on TT's) an NA exhaust will bolt right up and work fine but I recommend at least getting the performance cat-back which with the J-spec down pipes and NA cats will be a nice reasonably free-flowing setup.
The TT muffler sections have madrel bent piping and the NA ones do not. The TT resonator section has a smaller resonator because TT's make less noise (the turbos baffle a lot of it).
The catalytic converters include piping that go all the way up to the manifolds on an NA or to the precats on a US TT. The TT ones are shorter because the precats come down farther. The Japanese TT catalytic converter sections and the US NA are the same, because of those nice little downpipes that come off the turbo stock in Japan instead of the restrictive,in the way of everything, precats we have in the US.
10. The fuel system is also different. The fuel pump and fuel pump control units are different corresponding to the higher output TT injectors. But you can get by with the NA pump and control unit on a TT without extreme mods. The fuel rail, filter, pressure regulator, and dampener are all the same.
11. Of course the front facia is different with the gills in the bottom corners so air can get to the intercoolers. The facias are completely interchangeable but, if converting over most just buy an aftermarket facia (Stillen, WW, etc.), almost all of which will work for NA or TT. As you all know the TT cam with a stock rear spoiler.