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Rb25/30 Build


Slideways_Master
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Ok i own an r32 gts4 4 door and, well i got over the 20 prrreeetttyyy quickly and thanks to the old girl and my missus buying me an rb30 for my birthday, and buying a rb25de head i'm getting rid of the old 2ltr as much as it has been reliable and fun. Few question i have though upon doing my own research and not finding a consistent answer to any of my questions through VARIOUS workshops, magazines and other forums, google, altavista, bing, google chrome, blah blah etc etc i have decided to open this topic to see what more information i can get together

1st Q: RB26 cams we all know and love em, BUT will they fit into an rb25de head???... I know i can go tomei poncams, hks, crow cams etc etc, but i have to maintain SOME normality in this car as it does carry children....sometimes, rarely though but sometimes. and being that rb25de cams have not much better specs than '20 cams i'm going to ditch them, and go with '26's and cause i can and want to, i think...

2nd Q: WILL a gtr flywheel, clutch and pressure plate albeit they will all go together, will the flywheel fit the rb30 crank???

3rd Q: has anyone fit the oil squirters to the 30 block and if so how much did it cost?? YES i know you can ceramic coat the crown etc etc but i want oil squirters i know they can be done via drilling and tapping but as the top questions poses i would like to know who has done it and the cost, why, cause i can

4th Q: I am going to have to hook up a Q45 AFM already have 300zx afm for increased power, BUT is it really worth it?? or should i just go with power Fc de jetro???

5th Q: who makes 40thou' oversize pistons that i can get in oz??? or if needed can rb26 pistons fit due to the head change and the stroke length yes in know '25, '26 and '30 pistons are all 86mm from factory but i am trying to consider comp ratio??

6th Q: what do i need to do to obtain/maintain an 8.5:1 compression ratio???

This engine would be looking at around 5-600hp at the engine which would be around 450 to 520 hp at the wheels MAX on high boost and maybe if i want 350 hp on low boost. the way i see it is if an rb26 in stock form can make 300kw at all four in near stock form then i can do it here to with a little ingenuity.

it has the following supporting mods atm cold air intake (inclosed pod), 300zx afm, R32GTR gearbox, Bosch 040 600hp in-tank pump, HDI fmic, gtr injectors with impedance restrictor(already on the rb20), chipped rb20 ecu, t04, top mount and 38mm external gate, hks style cam gears, high po valve springs, n1 water pump, nitto oil pump, trip core rad, clutch fan (keeping).

AND would like a very sexy sounding nismo exhaust but it's got a straight through 3inch iteam instead that is going for a nismo sexy sounding one mmmmmm.

Ok so shoot gimme ya ideas and thoughts and knowledge PLEASE.

I also apologise if this may seem a little to straight forward in the typing but i'm over rude f*cks.

Edited by Slideways_Master
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Hey mate, what dump adaptor are you going to use?

And which intake so it doesn't foul the bonnet?

I was looking at doing this I'm my 32gtr, but have decided a different route.

I highly recommend reading through a lot of the topics in the 25/26/30 rebuild thread.

ALOT of usable info, and things you may not have thought of.

Also pretty sure I saw answers to most the questions you're asking.

Good luck with your project. And try and post up a thread whilst doing it.

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1st: yes up to 10.8mm lift, you will need to machine out head and as bubba said solid lifter conversion and make sure you get springs to suit the valve lift

3rd: 1 in about 20 blocks can be successful in machining for squirters. best bet is make sure the rods have the little squirter hole in them not as good but same idea

5th JE/ srp, cp, only pistons i recommend, mahle hypertech few others out there

6th how long is a piece of string? Nitto gaskets come in 1.2mm, 1.5mm, 1.8mm thick with 88mm gasket bore, plus deck height piston dome volumes combustion chamber volumes... best to leave to machinists

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what kind of power level would the 444cc gtr injectors be able to sustain/obtain at 100% duty cycle or is that something that the tuner would know relevant to the supporting mods??? and thanks gerg for ya info too everyone it.s much appreciated.

you need 600+cc injectors for the power you have said.

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i have 1000cc deatschwerks injectors in my 30/25 with 8mm or 10mm fuel lines to a 2.5L surge, bosch 044 pump with a no idea what feeder pump...honestly didnt check when i bought it they just hooked the external setup for me and i never asked.

went for a drive tonight with the laptop on my e6x (ancient but still good!!) and it claims 93% duty cycle for the injectors @ 26ish psi (boost gauge broke so my gauge that ive got for the time being only goes to 20psi, cheers calibre >.<)

low comp, cant remember where my sheets are but it was something stupid like 8.1 or 8.3. was built a while ago by this old school guy. decrompressed it a lil too much but it goes fine. might be higher? should probably find out.

that being said, my fuel consumption is quite catastrophic.

Edit: Would help if i said the power figure. its around 500hp at the 22psi mark with a to4z + forged. hasnt seen a dyno for a long long time, i play with it myself but im too poor for dynos, they are too far away AND it runs fine so I dont touch it. something i learnt a while ago lol.

Edited by pedl0r
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