Need Help Building Up My 25t

[nsta]

Hey guys, need some serious as to where i should start with my 25t.

I just done a compression leakdown test and tests show my motor is still all healthy:)

Car, r33gts25t 94 coupe auto

mods:

3" exhaust + split dump

apexi pod filter

hyrid front mount i/c

boost tap running 7 psi for now

all else is stock, i have a boost gauge and regularly mantain the car.

What i want to do is start pricing up peices one by one to buy, and put it all on at once, or would it be best to do it bit at a time?

Im aiming for 250rwkw, and the thread posted tells me pretty much most of what i need to know.few quick q's:

1)in what order should i start fitting items if not all at once.

2)what size injectors are best for application, would it be best to go large nismo 700's if wanting to aim for more power later on?

3)i see that clutch has been noted in the list, i have an auto, will my box be able to handle the amount of power im after?

4)Is 250rwkw a great increase in power against what i have now?will i notice a much better power band accross, as i feel my car is very flat mid-top end, heaps of bottom though.....which i thought would b the other way around...

[mad082]

yes 250kw will be a big increase on what you have now.

most things it is best to get all at once (mostly because you need them to run other things, like when you do the turbo you need bigger injectors and a new ecu, etc) others can wait (like good tyres).

and you are going to have a lot more lag than you currently do.

[nsta]

will 250 be a good setup for a 12sec 1/4 pass, im after a 12 daily driver and ill be happy:)

P.s when you say a lot more lag, is this true no matter wjat turbo i choose to pick?,

Ive decided on two items so far, which i'll be buying very soon.

Bosch 040 Fuel pump and a set of Nismo 550cc injectors, that should suffice for upto 300rwkw if i ever want to go that large shouldnt it?

[R31Nismoid]

Bosch 040 Fuel pump and a set of Nismo 550cc injectors, that should suffice for upto 300rwkw if i ever want to go that large shouldnt it?

Yep

[nsta]

cheers dude, im actually thinking of going for 740cc injectors, just cause the pricing is so similar, is there any drawbacks in going bigger injectors?or should i go for it???

P.s im from NZ, but come to these forums to learn more about the r33's:))as nz dont know much bout em

[SECURITY]

250 should be fine for the auto box, just make sure you fit a decent sized tranny oil cooler. Abo Bob has rebuilt his with kevlar bits, if mine ever blows or i choose to go over 250kw (whichever comes first) i'd give it the same treatment.

im not really interested in a manual conversion because ive beaten a few gtst's on the street who have the same mods and if theres no real performance gain then i dont see the point. autos are fun too

next step is a shift kit.

i'd do the mods in this order:

fuel system

turbo + computer + tune

suspension + wheels and tyres

[rs73]

700cc injectors might be an overkill for your target of 250rwkw.

I made 230rwkw with Bosch975 in tank fuel pump, HKS2535 and 16psi boost on standard injectors and stock airbox. To get up to here I needed a Z32AFM, powerfc and the usual 3" exhaust and a good FMIC (turn-flow ARC intercooler, which is only about 50cmx24cmx6cm, much smaller than the commonly used 60x30x6 or 7cm).

I estimated to get 250rwkw you may need to do:

1) slightly bigger turbo e.g. the HKS2540 or GTR-S, 2nd hand can be picked up from as low as $1500-1600 to $2000-ish depending on condition.

2) and perhaps a set of NIsmo 555cc injectors or probably 6x JDM S15 480cc injectors could be sufficient already. I recommend getting BRAND NEW for $600-900 a set. Your stock AFM will max out so you better source a BRAND NEW Z32 AFM for $400-ish. Get Nismo or Tomei or Bosch, they're exactly 100% OEM NIssan AFM just being sold through different channel. These 2 (injectors and afm) are the only things I strongly recommend worth paying the extra $ to get brand new only, everything else (turbo, fmic, exhaust, powerfc, etc) can be 2nd hand. Then at my current level my stock coil is struggling so I was recommended to get a set of Splitfire coils if I want to get more power with more boost - that's another $600-800. I stick with my stock one for now, happy with 230rwkw. with splitfire I may end up about 240rwkw and nearing the efficiency of my small 2535.

3) no idea about clutch, but currently I had the hybrid exeddy clutch single plate installed during my auto-to-manual conversion about 3 years ago. not saying auto is bad, but I bought my auto and after almost a year, I missed driving a manual (a manual driver for 14 years - I just cant get used to leaving my left foot idle). For your auto gearbox, you may need your stall converter and drive belt strengthened - probably contact auto trans specialist. $$$ wise I'm not sure.

4) with power on the top you're most likely always loose response down below. for comparison my stock turbo boosted at 10psi only made 190rwkw max but a lot more responsive and press you at the back seat hard. with only marginally bigger one like HKS2535 that sensation is "softened" a bit, although an increase of 40kw to 230rwkw is noticeable. fitting a cam gear ($300-ish) and have it tuned, the tuner can move that power band by moving the torque lower, but you loose top end. Or if you want to go to dyno power war, move the power up at the top range, but it will become laggier and less responsive. You'll need to ask yourself a question what you really want and decide which trade offs you prefer.

and after all those, don't forget tuning and fitting labour cost can easily cost you from $500-$1000

unless you know a mate with a dyno and a hands-on person yourself with powerfc tuning and stuffs.

Oh and for boost controller (u will need one if you want to go over 7psi) if you can afford it get the electronic ones like Apexi AVC-R or HKS EVC. Maybe from $300 to $1000 depending if used or new, could be less for older models. A cheap bleed valve is sufficient but I've seen some dodgy well known branded bleed valve that creeps and spikes and could have killed my engine 3 years ago if my tuner didn't find out soon enough that it's stuffed (I'm not gonna start naming brands). There's a non-branded one in blue colour going around in this forum and from people's story they hold boost well, but I personally haven't used them. I used HKS EVC.

[nsta]

Thats some great advise/knowledge mate,thats why i keep coming back to these forums:). I forgot to mention, i have some wheels/tyres already, and couldnt pass up some good coilovers so i am getting those very soon.

265/35/18 Rear x 9.5

245/40/18 Front x 8.5

Suspension......BC Coilovers, damper and height adjustables.....anyone in aus heardof them?,they are one of the best packages out here in nz.What other supporting sus mods may i look into getting?

On Dtm wheels blitz 078.....weigh a truckload, and may go to something lighter like some work meisters/ssr wheels, also the tyres suck,i pretty much bought whatever i could afford at the time. Aside from the tyres, could i easily get away with using such heavy wheels or should i think about getting lighter ones. My long term goal is to get a daily driven 12sec car, that still looks good:)

Alright, i may just get some 555 nismo injectors,and look into getting a z32 afm.....i source most of my gear from greenline....if theres any better deals out there please do tell me.

P.s: Dont know whether to keep auto or not, i may wait for it to break before converting.....but just in general....will i just need a good trans cooler for it, and regularly mantain it to get to where i want?......and what ecu eill an auto need for tuning?main reason i want to go manual is so i can buy a powerfc tune....which autos supposedly cant do

Edited September 1, 2006 by nsta

[nsta]

Hey people, do the z32 nismo afm's plug straight into an rb25det???is there any adapters/plugs i'll need to purchase on top to install?

These are selling on nengun for a special price atm so i dont want to pass up a great deal, i know ill need to have it tuned at the same time,but im going to worry about that later.

Heres the part no of the afm: 22680-30P00(is this the one i need), it suggests i pick up the tomei afm adapter as well....is this what is needed aswell?

thanks in reply

Edited September 1, 2006 by nsta

[Muz]

Hey people, do the z32 nismo afm's plug straight into an rb25det???is there any adapters/plugs i'll need to purchase on top to install?

These are selling on nengun for a special price atm so i dont want to pass up a great deal, i know ill need to have it tuned at the same time,but im going to worry about that later.

Heres the part no of the afm: 22680-30P00(is this the one i need), it suggests i pick up the tomei afm adapter as well....is this what is needed aswell?

thanks in reply

Nope, you will need to re-do pins.

cheers

Muz

[rs73]

nsta,

Get the Z32 AFM plug, go to nengun and go into the tomei/nismo afm product page and there is a link to get the plug in that page.

It comes with a proper plug so save you the hassle of trying to butcher the socket on the AFM to suit your RB25 plug. The plug came with about 10-20cm length of wires and you just need to cut off the wires of your stockie plug and match up the ground, air flow signal and 12V power wires together. There's a chart somewhere on this forum, just do a search on DIY section.

and by the way your tyres should be sufficient, providing they're not some dodgy ultra-long-lasting rubber that just doesn't grip at all. I had 235/45R17 Dunlop SP3000A only on my cars, pretty grippy, not as grippy as SP9000 or S-03 as most people said but that is still enough.

I've never heard of BC shocks but I've got a full whiteline shocks, bushes and swaybars. That really stabilises the car and remove that unpredictable twitchy rear end on power acceleration.

[nsta]

cheers, so i should purchase the nismo z32 afm+tomei adapter plug then right?no hassling around with wiring then.

Im gathering all the parts i need now,and will do everything in one hit i think

[rs73]

Yep,

You'll still need to rewire the plugs but it's a lot easier job, and as yours is '94 gtst so it'll be the S1 R33 AFM like my '93, so the wiring translation is more like one to one. Series 2 ('96-98) R33 AFM needs two of the wires joined together to one Z32 AFM's wire.

Doing it all in one go is a good idea if you can reach deep into the pocket and have all the dollars up front now. I had to slowly do mine over a period of 4 years span... as I'm not someone who can pull money out of my ears just like that. in the end it's more expensive I believe (e.g. going to dyno 5-10 times instead of 2-3 times), but I got no choice. But I don't regret my efforts, and the car has come to a state where I'm happy with the power..

[nsta]

yeah, im actually thinking about that myself, the way im going i may be there in hoepfully 6months to have everything ready to put in.....what mods could i easily install without any adverse effects.....i know the afm will need an ecu to tune....so those two are out of the picture.....any reason why i shouldnt chuck in little things like injectors/fuel pump right now with what i have?as long as it keeps the car running smooth ill do it, or else i can wait....but i think a fuel pump may help my car right now, as im already getting fuel cuts!.......things that need a tune to benefit ill wait on fitting, like the afm for instance........

p.s is a fuel regulator something i should be looking into aswell........which should pretty much take care of the fuel side of things

[nsta]

being a daily driver, im more interested in street application....so more down low-mid response is what im after....but no to say i wnt to lose all top end......is there a middle line i can choose which could suit me...i love the responsiveness of the stock turbo....but understand that a larger turbo will slightly diminish that....but improve power output higher up

[rs73]

Without the Z32 AFM and ECU it'll be very hard to get your target of 250kw. Stock RB25 AFM maxed out around 210rwkw. And you can't use Z32 AFM with stock ECU, u'll need something like PowerFC or any other aftermarket like Wolf3D, Motec, etc. But I forget you had an auto so PowerFC is out of the question. Fair enough, but maybe you can use Z32 AFM and Apexi SAFC to "trick" the stock auto ECU to think you still have the RB25 AFM there, or some tuners I heard put a resistor in the AFM wiring to trick the ECU as well. Both way will still need time to mock around on dyno to get it right.

Most stock ecu R33 gts-t only get up to about 180rwkw~190rwkw when tuned by a good tuner, above that the ECU just can't handle the extra boost and getting itself confused. With piggy back like SAFC that may be a solve to your problem, but I had SAFC before and I only get up to about 180rwkw before I decided to not further trying and switch to PowerFC.

Your stock turbo while can be boosted to 12psi, it may not last that long on daily basis. Most people I know wind it back down to 10psi to maintain reliability. That's why you need bigger turbo, but if you don't want to have a 400kw drag monster that lags down below, you'll need to keep to either GT25 series turbo or GT-RS, otherwise you can have GCG to rebuild and hi flow your stockie.

Most of the time you can't have the best of both world, mate. You either have to choose one or the other.

Last resort is you can try supercharging your rb25 for low rpm response and then using a clutch system to stop the supercharger overspinning up to x rpm and from then on your big (e.g. T51) turbo would have already spooled up and kicks in. But this exercise is very expensive, and from the engine management point of view can be very hard and complex to tune - it's almost not worth spending the money on it.

[nsta]

Hey, im going to go manual/power fc + z32afm mate......im just gathering all the bits one by one......I hear its better to keep the auto shaft when going manual as theauto has a better ratio for acceleration....can anyone confirm this.....and what advce would you reccomend for a first time auto to manual skyline r33 gtst conversion....

What parts are needed for the conversion....and which clutch will suffice for up to ~280-300rwkw if i ever want to reach that high....i may speak to jim berry about this as i heard he's a GURU in this subject.....and doesnt mind speaking:)

[rs73]

You can't keep the shaft mate, auto and manual drive shaft has different length.

If you talk about ratio what you mean must be the diff. Yes you can keep the diff in this case, I kept mine 1:4.3 diff from auto, but you use more petrol as it's about 5% higher than manual's 1:4.11 and that means when your speedo shows 100km/h, you're actually only travelling 95km/h and to be in the same actual speed with another manual R33 skyline, you'll need to travel at 105km/h according to your speedo, which means you'd be running in 3000rpm instead of 2600rpm for example when on 5th gear cruising on freeway and use more petrol.

Acceleration wise people say it'll feel stronger than factory manual diff, as most aftermarket diff like Kaaz or Nismo for R33 skyline are made in 1:4.3 ratio. But to this date I have not felt any difference yet.

Best is to get an experienced mechanic to do the conversion, think about $5000 all up depending how much it cost you to get parts.

That was how much it costed me 3 years ago including all parts and labour (minus gearshift knob) but my price included timing belt change since the engine is out of the bay. You may want to change your timing belt while your engine is out if you decided to go with the manual conversion.

280+ rwkw is doable in RB25 but you'd probably need to start doing a full rebuild of your engine. That I heard is at least around $5000 to do.

Stock RB25 internals won't last long at over 250rwkw.

[nsta]

im not planning on a rebuild....but when the time comes, i guess i have no option.....imin the process of getting a manual box right now:)

[nsta]

whats a good tyre pressure for 265 rears, 235 fronts for street driving, and also i just got my coilovers fitted, and ive set them to soft atm, whats a good setting to use for damper(ride gets very harsh on hardest setting), but grips great!