Over the past two years i've been converting my car from a september 91 build date 4g63 nt over to a gst. As you've most likely seen user xhypno has a fairly well put together setup for sticking a set of turbo only parts onto your nt and creating a 7psi or so car. Now this is a good deal for most people since they aren't looking for the kind of time or money it takes to do a full conversion like i did to my car, also it eliviates some of the troubles high hp dsm's have.
On the other hand though it limits you severely in the type of power you can make. The piston ring lands on the nt pistons (now we're mainly talking the nt 4g63 here) are in a terrible position. While more than sufficient in strength for a nt motor only pushing out 135hp out of its 2 liters, once boost is added problems suddenly arise. The ring lands are so high up on the piston skirts that a shockwave from pre-ignition (knock) can easily crack the land causing the ring to separate, lose compression, and god forbid internal engine damage. The obvious cure to this is to simply replace the pistons, but we're going to go a little farther than that, although we will spend some time on that as well.
Okay first off the swap we're going to be talking about is going to pertain to a 1991-1993 nt 4g63 in which we completely swap in a domestic or jdm turbo 4g63.
Choosing the engine:
Getting ahold of the engine and its accessories is the most important part to not spending all friggin year trying to pull this off. I believe that there are only a few really good methods in going about this. And for god's sake get a 6 bolt while you're at it.
One: Find someone with a wrecked awd or fwd turbo. I personally picked up my engine for $1200 with my choice of whatever accessories i wanted.
Two: Search the junkyards for a complete car with engine and all accessories still attached to it. Most could probably be had for nearly the same price as buying one off of an individual.
Three: Build or buy a jdm engine and then find either a local parts car or one in a scrapyard to get ahold of the accessories you either won't recieve, or in the case of the jdm, may be damaged.
Engine accessories: First we'll assume that you were lucky enough to find a complete longblock 6 bolt through either a fellow dsmer, performance shop, or scrapyard. Now the list of things you will want to get ahold of that pertain to the engine.
1. complete turbo long block (blcok and head including internals and bolted attachments such as oil pump and such). - already been covered
2. mass air sensor - the turbo mass air sensor has a 7th wire coming out of it as opposed to the nt's 6 wires.
3. fuel pressure solenoid - not really needed, but can be setup just the same as stock
4. turbo intake manifold and throttle body - the turbo intake manifold is already tapped with the vacuum line nipple for the bov, also it has the correct studs in it to use the turbo throttle body and elbow.
5. turbo exhaust manifold - pretty self explanatory hopefully, although make sure its at least for a 14b and not the automatic's 13g with the smaller opening.
6. turbo and related cooling and oil lines - now here is one that's an option. you can either go with a trusty 14b for awhile and stock lines or step up to the plate with a combination of any turbo/ oil feed line.
7. intercooler (side mount or front mount) - you will need!
8. intercooler piping-i reccomend starting with a sidemount and stock piping for most people to keep the initial cost down.
9. turbo fuel pump - this is an absolute must have, the nt fuel pump has no business handling boost.
10. BOV - stick with the stocker for now, its a great design and its cheap and adaptable.
11. turbo injectors - get the 450cc's from a 5 speed.
12. injector resistor pack - little gray case on the firewall, 5 wires coming out of it. you need this badly, we'll discuss hooking it up later on.
13. 1g fwd downpipe - you will have to ditch the stock pre-cat setup. if you can't make your own buschur sells a well priced 2.5" pressbent that hardly necks down at all for a good price.
14. wastegate solenoid and mbc - you will want the stock solenoid (the one you do the free mod to) as some people experience a rather annoying check engine light without it. get this even if you are getting an mbc just in case.
15. knock sensor - check the condition of the old one you got, if all the goo is running out of it, expect high counts of knock and prepare yourself to replace it.
16. o2 sensor - the wiring for the o2 sensor is longer in order to reach across the manifold and down to the o2 housing.
17. thermostat upper and lower housings - the thermostat housing has the extra lines built into it for the cooling of the turbo and oil filter.
18. coolant cross pipe - this also has a coolant line for the turbo built into it.
19. oil filter cooler - now this is going to be a needed item although make sure and match it up to numbers 17 & 18 so that they're all the same year.
Transmission:
Well now that we have your engine hopefully all accounted for and in order we need to move on to putting that power to the ground. There are a few different methods here and you are free to choose whichever you like.
1. retaining the 1g nt tranny - the 1g nt tranny can be retained in this fiasco in its exact form. you simply need to also utilize the 1g nt clutch and flywheel. 1g nt 4g63's came in 6 bolt and 7 bolt designs the same as the turbo cars did. since you hopefully chose a 6 bolt turbo engine having a 92 and up car can cause some problems with this. assuming your flywheels match up though, prepare to do some grinding. the turbo crankshaft has a locating pin on the end of it for the turbo flywheel, well as i'm sure you've noticed by now the nt flywheel doesn't have a little alignment hole for this. no big deal, simply grind the nubbin smooth (and make sure it is completely smooth since its the flywheel's mating surface to the crank and you wouldn't want a wobble there). i personally started by using a hard cutting disk on my dremel and then using a grinding stone to finish the job off. you will want to upgrade the stock nt clutch as it is totally uncapable of withstanding anywhere near 200hp. mine lasted a month of careful driving i believe. as far as buying nt clutches go, the choices are out there, but i personally don't have alot of experience with most of them (and am shopping for a replacement of the current one i have). most upgraded clutches should be able to contain the power available from a 14b but above that is apparently yet uncharted territory.
2. using a gst transmission - the gst transmission is a pretty simple install, although it can have its bugs. you'll need to make sure you have the flywheel, clutch, transmission, and rear aluminum cover from all the same year. of course you have to buy all of this so alot of people don't go this route. one of the nice things though is that alot of the mods companies like tre, bmtranny, and shepherd sell will work in this transmission as opposed to the nt in which they won't. the other nice thing is that this transmission has been proven to work at high power levels (although i don't see why the nt tranny would suddenly fail).
ECU and wiring harness: now we're into the most complex part of this all. the ecu/ wiring harness. there are again two ways of pulling this off, one cheap and labor intensive the other slightly more expensive but easier.
1. retaining the nt harness - the nt harness can be completely retained and only needs the addition of some wiring to become the equivalent of the turbo wiring harness.
what you'll need to wire in:
7th wire from mas - the 7th wire from the mas needs to be run back to pin number 6
knock sensor - one wire can be grounded to the engine bay somehow, the other white wire needs to be run back to pin number 9 on the ecu.
wastegate solenoid - one wire here will be grounded, the other returns to the ecu at pin number 105
injector resistance pack - this is the most dificult. i'll let the following pictures describe it rather than trying to explain it in text. if you have any questions just ask.
thanks to don over at aialmatrix for getting mine to run and making this great diagram.
here's a link to my imagestation account where i have the factory ecu prints. the highlighted ones need added, and the model is in the upper corner so you don't get confused.
http://www.imagestation.com/album/?id=4291950155
If there are any more questions feel free to ask away in this thread. but let's limit the "that's cool" and other pointless posts. i don't want this to grow as thick as the other one where you have to wallow through 240+ posts to get your info.
On the other hand though it limits you severely in the type of power you can make. The piston ring lands on the nt pistons (now we're mainly talking the nt 4g63 here) are in a terrible position. While more than sufficient in strength for a nt motor only pushing out 135hp out of its 2 liters, once boost is added problems suddenly arise. The ring lands are so high up on the piston skirts that a shockwave from pre-ignition (knock) can easily crack the land causing the ring to separate, lose compression, and god forbid internal engine damage. The obvious cure to this is to simply replace the pistons, but we're going to go a little farther than that, although we will spend some time on that as well.
Okay first off the swap we're going to be talking about is going to pertain to a 1991-1993 nt 4g63 in which we completely swap in a domestic or jdm turbo 4g63.
Choosing the engine:
Getting ahold of the engine and its accessories is the most important part to not spending all friggin year trying to pull this off. I believe that there are only a few really good methods in going about this. And for god's sake get a 6 bolt while you're at it.
One: Find someone with a wrecked awd or fwd turbo. I personally picked up my engine for $1200 with my choice of whatever accessories i wanted.
Two: Search the junkyards for a complete car with engine and all accessories still attached to it. Most could probably be had for nearly the same price as buying one off of an individual.
Three: Build or buy a jdm engine and then find either a local parts car or one in a scrapyard to get ahold of the accessories you either won't recieve, or in the case of the jdm, may be damaged.
Engine accessories: First we'll assume that you were lucky enough to find a complete longblock 6 bolt through either a fellow dsmer, performance shop, or scrapyard. Now the list of things you will want to get ahold of that pertain to the engine.
1. complete turbo long block (blcok and head including internals and bolted attachments such as oil pump and such). - already been covered
2. mass air sensor - the turbo mass air sensor has a 7th wire coming out of it as opposed to the nt's 6 wires.
3. fuel pressure solenoid - not really needed, but can be setup just the same as stock
4. turbo intake manifold and throttle body - the turbo intake manifold is already tapped with the vacuum line nipple for the bov, also it has the correct studs in it to use the turbo throttle body and elbow.
5. turbo exhaust manifold - pretty self explanatory hopefully, although make sure its at least for a 14b and not the automatic's 13g with the smaller opening.
6. turbo and related cooling and oil lines - now here is one that's an option. you can either go with a trusty 14b for awhile and stock lines or step up to the plate with a combination of any turbo/ oil feed line.
7. intercooler (side mount or front mount) - you will need!
8. intercooler piping-i reccomend starting with a sidemount and stock piping for most people to keep the initial cost down.
9. turbo fuel pump - this is an absolute must have, the nt fuel pump has no business handling boost.
10. BOV - stick with the stocker for now, its a great design and its cheap and adaptable.
11. turbo injectors - get the 450cc's from a 5 speed.
12. injector resistor pack - little gray case on the firewall, 5 wires coming out of it. you need this badly, we'll discuss hooking it up later on.
13. 1g fwd downpipe - you will have to ditch the stock pre-cat setup. if you can't make your own buschur sells a well priced 2.5" pressbent that hardly necks down at all for a good price.
14. wastegate solenoid and mbc - you will want the stock solenoid (the one you do the free mod to) as some people experience a rather annoying check engine light without it. get this even if you are getting an mbc just in case.
15. knock sensor - check the condition of the old one you got, if all the goo is running out of it, expect high counts of knock and prepare yourself to replace it.
16. o2 sensor - the wiring for the o2 sensor is longer in order to reach across the manifold and down to the o2 housing.
17. thermostat upper and lower housings - the thermostat housing has the extra lines built into it for the cooling of the turbo and oil filter.
18. coolant cross pipe - this also has a coolant line for the turbo built into it.
19. oil filter cooler - now this is going to be a needed item although make sure and match it up to numbers 17 & 18 so that they're all the same year.
Transmission:
Well now that we have your engine hopefully all accounted for and in order we need to move on to putting that power to the ground. There are a few different methods here and you are free to choose whichever you like.
1. retaining the 1g nt tranny - the 1g nt tranny can be retained in this fiasco in its exact form. you simply need to also utilize the 1g nt clutch and flywheel. 1g nt 4g63's came in 6 bolt and 7 bolt designs the same as the turbo cars did. since you hopefully chose a 6 bolt turbo engine having a 92 and up car can cause some problems with this. assuming your flywheels match up though, prepare to do some grinding. the turbo crankshaft has a locating pin on the end of it for the turbo flywheel, well as i'm sure you've noticed by now the nt flywheel doesn't have a little alignment hole for this. no big deal, simply grind the nubbin smooth (and make sure it is completely smooth since its the flywheel's mating surface to the crank and you wouldn't want a wobble there). i personally started by using a hard cutting disk on my dremel and then using a grinding stone to finish the job off. you will want to upgrade the stock nt clutch as it is totally uncapable of withstanding anywhere near 200hp. mine lasted a month of careful driving i believe. as far as buying nt clutches go, the choices are out there, but i personally don't have alot of experience with most of them (and am shopping for a replacement of the current one i have). most upgraded clutches should be able to contain the power available from a 14b but above that is apparently yet uncharted territory.
2. using a gst transmission - the gst transmission is a pretty simple install, although it can have its bugs. you'll need to make sure you have the flywheel, clutch, transmission, and rear aluminum cover from all the same year. of course you have to buy all of this so alot of people don't go this route. one of the nice things though is that alot of the mods companies like tre, bmtranny, and shepherd sell will work in this transmission as opposed to the nt in which they won't. the other nice thing is that this transmission has been proven to work at high power levels (although i don't see why the nt tranny would suddenly fail).
ECU and wiring harness: now we're into the most complex part of this all. the ecu/ wiring harness. there are again two ways of pulling this off, one cheap and labor intensive the other slightly more expensive but easier.
1. retaining the nt harness - the nt harness can be completely retained and only needs the addition of some wiring to become the equivalent of the turbo wiring harness.
what you'll need to wire in:
7th wire from mas - the 7th wire from the mas needs to be run back to pin number 6
knock sensor - one wire can be grounded to the engine bay somehow, the other white wire needs to be run back to pin number 9 on the ecu.
wastegate solenoid - one wire here will be grounded, the other returns to the ecu at pin number 105
injector resistance pack - this is the most dificult. i'll let the following pictures describe it rather than trying to explain it in text. if you have any questions just ask.
thanks to don over at aialmatrix for getting mine to run and making this great diagram.
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here's a link to my imagestation account where i have the factory ecu prints. the highlighted ones need added, and the model is in the upper corner so you don't get confused.
http://www.imagestation.com/album/?id=4291950155
If there are any more questions feel free to ask away in this thread. but let's limit the "that's cool" and other pointless posts. i don't want this to grow as thick as the other one where you have to wallow through 240+ posts to get your info.
