R34GTFOUR

the rb30 in a gtr isnt a simple as most make it out, or as cheap. I sat down the other day and did a few calculations for my car and was in abit of shock ahaha (im still doing it lol) remember with the rb30 you'll defiantely need an awd adaptor (proengines is around a grand), you would rebuild it since its most likely 200k km old, and while your there you'll probably go silly and put some forged goodness in there, thats not including the turbo, manifold etc needed. All of a sudden the engine is costing you over 10k when you can get a used 26 for 4k complete and bolt it in, albeit its not going to be a "fresh rebuild" but theres a reason rb26 are well like, they make great power and are pretty much bulletproof when driven right.

all comes down to money i would do it if i had the extra coin...

just get a standard hg from nissan, that should do the trick, otherwise you can get aftermarket metal hg but you'll be looking around the 300-400mark. The stock hg will suffice are you replacing everysingle conrod or just one? what are you replacing it with, 2nd hand, new, stock, aftermarket forged, rb26 rods?? theres too many variables to put an accurate price on it. but a basic bottem end freshen up with new rings bearings etc, i would expect to pay the 4-6k mark to the mechanic

aahhh the joys of modding cars... sorry to hear, hopefully warrenty covers it

and it begins... haha definately have some nice parts there, hope it all goes well for you

yep the gtfour , i have a big lest of parts that i have written down to get, everything SHOULD slot in nicely. I'm getting a proengines 4wd adaptor, gt35r, already got the 6boost manifold, ported greddy copy plenum etc etc, the list is a long one i'll definately be getting your rods and the low compression 8.2 CP pistons so with the less cc head that should bring it up to 9ish depending on hg (im waiting for you to do yours first to make sure its a-ok hahaha) the only thing im uncertain on is the springs, i might give that mob a call this week and see what they can do.

are you running a bov? that chuffing/flutter noise is compressor surge, which slows the compressor speed quite alot during gear changes or when you back off on the accelerator, which can cause lag inbetween gear changes. what boost gauge are you reading off? also what turbo setup are you running? also that standard airfow meter would of been maxed out ages ago, my bet its at 5volts at 4500-5000rpm, so get a z32 and get it retuned

cheers for the reply i did a search and you recommended that mob in a few posts haha, which is good but a few people also said somethings that made me abit weary, I've still got about 6months up my sleeve before i start the build so i have a bit of time to sort it out. How much did they slug you for a set of springs if you dont mind me asking? I've seen anywhere from 300-600 for a set (tomie) as soon as i sell my spare car i'll be msg you for some spool rods and cp pistons for the NEO

could of been a custom water to air intercooler guys.....

hey mate, its common for nissan afm's with a plug designed for 6 connections, only to have four wires running to it, and the second series only had 3 wires just to confuse you more haha Anyway if you afm is off a series 1 rb25det than just wire it as the digram shows you. Are you going to be using it on a maxima or a skyline? The power feed is 12volts so with a multimeter you'll be able to find that one out on your harness on the car, likewise with the 2 grounds, which just leaves the signal wire (and since there is only 1 wire left, it has to be that one) By using the mulimeter wire, probe the signal wire (thats a postive line), and with the igntion on but not the car started it should read about 0.2volts. With the car on and running at idle it should read anywhere from 1.0-1.4volts. The stock skyline afm is know to run out of "range" at the 270-280rwhp mark, which will read as a max of 5volts at the signal wire (thats as far as it can go). A z32 afm is a better option and is a common upgrade if you going to be running more power, and can be had for less than $300 so its a cheap upgrade to. hope that helps

Hey everyone, just wondering if anyone that is knowledgable with the neo series rb25's can shed some light on this for me. Im going to use my rb25de neo head on a rb30 conversion. I was intially going to change to valve springs since i was going to use a set of tomie pon cams (Duration: IN,EX 260 Lift: IN,EX 9.15mm) and after hearing all the people having trouble with r33 na heads with valves floating because of soft springs i thought it was a good idea. Anyway. i've since been lead to believe that unlike the r33's, the neo head uses the same valve springs for both the na and turbo setup, with only the cams themselves being different, so im asking myself will springs be needed?? So how far have people taken the stock neo valve springs? The 9.15 lift of the cams shouldnt be a problem, and the rpm limit will be at no more than 8000rpm so again that should be ok, but if i was running near on 1.8bar of boost with 500+awhp will the springs be upto the task? Even if i wanted to stick some new valve springs in, im finding it hard to find springs for the neo head. The neo head as many of you know uses solid lifters, so the only springs i came across that might work at the r33 tomie spings rated to 10.25 lift but designed for solid lifter use. So im wondering if the springs are different between solid and hydrolic lifters, im wondering if r33 valve springs designed for solid lifter work with my setup?

thread updated, ONLY THE TEINS TO GO!! someone must be after a great strret/track setup?

^^ +1 if you dont have vac assist your going to have that hard pedal feeling, the brake booster is either leaking internally (which you should be able to hear), or the line itself is leaking. If you hearing that hissing noise, thats most likely your problem

just thought i would post up some pics of the ute (i edited the first post)

yep as far as i know its just the bellhousing that needs to be swapped. The box itself is idential

PROBLEM SOLVED Okay so there was 4 main areas from stopping the rb25 from running properly: 1. The powerfc was faulty, it didnt give out a tps voltage, I stuck my bros powerfc in it and it works fine. Hopefully he can get his fixed under warrenty 2. He wired in the z32 afm plug so i just doubled checked the wiring. He was using a diagram that listed the wiring code as 1,2,3,4,5 (5wire plug), going from left to right, but the actual plug has the numbers 1-5 but 1 starts on the far right hand side. What this means is that he wired the signal and voltage back to front (SATO GTS, you were spot on haha). I re-wired it and it works fine now 3. The tps that he had on the q45 wasnt actually a tps, but a throttle switch. The switch was either on or off, there was no variable to it. I stuck my q45 tps, which was the proper tps and problem solved. 4. Now this last problem got me stumped for a while, and this is what was causing the hunting at idle. On the q45 throttle body it has its own idle up. It uses a coolant line going though it to warm up this valve, and once it hits operating temperature it pushes the throttle back to fully closed. Since we arent running any coolant to it, the throttle was open too much at idle so it was getting to much air and confusing the ecu making it hunt. I pulled the whole assembly off the throttle body and adjusted the idle screw and it now sits dead on 800rpm, no hunting. So after a LONG weekend, a car that barely started and hardly ran now starts first go, idles smoothly, and if the diff ratio wasnt so tall would be pretty quick, but it still revs freely and cleanly. Its going to get tuned and the boost upto 12psi and it should go alright for a hq ute. Thanks again for everyone that replied, especially paul, it helped me alot. Cheers

99% sure its different purely because on the rb25de in a gts4 the bottom of the block where the sump and diff bolts up, is wider to make it stronger to support the extra weight and power from the front diff. You would have to get one of those kits from proengines i think it was, that makes the adaptor plate so you can bolt the front diff up, but its around the 900 mark so it might out way the good price of the neo engine. A stagea neo engine is the way to go for you, already has the front diff and sump and you just drop it in

i've never heard of that, but it could of happened. abs doesnt effect how easy it is to lock up, thats purely down to your tyres, suspension and road condition. The abs will only help the tyres from staying locked up. ie you slam on the brakes, it will lock up but pretty much straight after that the brakes will pulsate (the abs) to help it from skidding. what tyres/suspension are you running?

yeah i'll have a closer look at that tomorrow, although the plug looks fine and i always tighten the bolt to secure it all the way (i even press the outside edges of the plug cause the plug doesnt always go in evenly). The actual harness itself hasnt really been molested too much, 99% of its be untouched. The only thing thats been "tapped" into is the main power (3pinouts), eccs relay was made up, water temp and tacho feeds to the dash, and the starter signal from the igntion barrel, and all these things check out as good. I'm starting to feel sorry for the owner cause everything that shouldnt go wrong, has. I mean the odds that his q45 tps, z32 afm and a brand new power ALL being broken are almost statistically impossible but they are haha, i was intitially expecting one thing to be wrong lol Everything besides the stable idle is working fine. The car revs fine, and powers beautifully right to limiter, no surging and spluttering, it just hunts. Anyway i'm given up for the night, its only got a front pipe as an exhaust so its bloody loud and i dont want to get noise complaints, i'll wake them up first thing in the morning with it haha. So tomorrow: -Im taking my bros powerfc (the owners original powerfc is broken) out and putting it back in his skiz to make sure everything still works as it should (even though i just deleted his tune lol) -I'm going to let the skiz run then record all the sensor signal voltages, then put the powerfc back into the hq ute and compare the signals, hopefully something jumps out at me. -If not, im going to go pinout to pinout and record each and every value and compare that to the workshop manual and see what it says. -If still no joy, i will purchase some fuel and some matches and burn the bastard down to the ground.... once again thanks, your input has helped me alot

you may have to overnight parts from japan...

as for the hunting side of things, i have reset the powerfc and gave it 30mins to "relearn" its idle, but it didnt work I kinda knew it wont stop hunting the second i started it up with the reset ecu, it hunted straight away. When we first put a powerfc in my bros car, it never hunted at idle, it just ran really rich until it learnt the idle then it was all good. BUT... (and there is always a but haha) if i took timing out from the powerfc (about7-8degrees so its at about 8degrees BTC) then it stops hunting and idles at 950 but its not a normal idle. It kinda sounds liek its struggling even though the rpm doesnt change. If i return the timing to 15 BTC it starts hunting again. so yeah... still thinking...

haha you need abit of humour when your day is going like shit... anyway im guessing the z32 afm is shagged aswell, is there any resistance test or anthing to test the actual afm? so another update: I have a spare q45 afm, which i thought i would try. I hooked it up and the afm volts started to read as they should around the .2-.4volts when the engine was off but in the igntion postion. It was around 1v at idle, although it ran very rough (i had it on the vh41 setting for airflow) I then stuck the stock r33 airflow meter and took it for a drive. The volt reading was simular to the q45, and the car reved as it should and there was no spultering or anything like that throughout the rev range. But it hunts at idle now... 700-1400rpm just goes up down up down. So i now am concerned about 2 things, 1. why is it hunting? 2. why didnt it like my q45 afm even though i had it on the right afm setting? I'll try and get some pics of it, the owner has done a decent job at making it look good, now it just needs to go properly haha thanks again

i took the powerfc out and tested it on my bros skiz and it didnt give out a tps power, so the powerfc is buggered for some reason. I got my bros powerfc and plugged it into the hq ute and guess what? its got tps power, so its definately the orginal powerfc thats got a problem, its not the car. Anyway i started it up, still with the standard afm and it purred like kitten haha, so i though i would stick the z32 afm back on... THEN... The car idles rough as guts and the afm voltage is at 3volts, so its way off. I selected the correct setting for airflow meter setting on the powerfc, but it still reads 3volts. I checked, then re-check then double checked again the wiring going to the afm and its correct. So why would the afm give out a false reading? Im going to try and clean it, but whats the chance of this guy having all these things wrong, and ALSO have a busted afm? thanks

I just tried starting it on the powerfc, seems to run fine, its revs freely but it just idles too high (and still shows no tps voltage) also on a side note (and i doubt this will affect it, but who knows..) The owner has installed a speco tacho, it will read fine on the power fc, but plug the stock ecu and it wont pick up at all. The feed has just been tapped into the harness where the tacho pinout is on the ecu so its the same for both ecu's. Its another weird thing...

ok just a quick update, i've wired in the stock r33 afm, set the tps on the q45 throttle body to .4V on fully closed and connected the stock ecu and VRRROOOOM. The thing starts, idles, revs, it does what it should Then the spanner is thrown into the works... I connected the powerfc, I havent changed anything but the ecu, and now no tps voltage Im going to test the powerfc on another skiz in the next hour or so, but im still scratching my head. I'm really keen to find out why its doing what it is doing. If the powerfc turns out fine, then im just going to run a 5volt positive to the throttlebody on a external line. any other ideas?