Need Help With Rb25det Twinturbo Build

[brother_david]

Hey!

I came over a cheap twin HKS 2530 set for a GTR a while ago and now im going to put them into my R33 GTST.

I was planning on going with twins (turbos that is ) earlier and when these came up i couldnt let them pass me by!

Now i would really appreciate if someone has got some useful information about the procedure, things like going top-mount or not, best way dealing with water/oillines etc. I've looked around alot for twinturbo build pics and found some that are really useful but i feel that its better to know things before i start building then finding it out myself on the way!

List of my mods now:

HKS intake system with the lousy fungys type-filter

5Zigen Catback

Greddy BC

HKS Turbotimer

FMIC

Intank Walbro 255 lph

Inline Walbro 255 lph (disengaged for now)

Cusco Brake cylinder stopper

RPS Max Series Clutch

On their way, as in somewhere in a postoffice :

Stand alone engine mangement

Q45 AFM

Injectors (not ordered yet)

I will also rebuild the bottom end in a while but not just yet, but in the meantime i wanted to get the hardware sorted. Didnt mention other mods done to the chassie since they dont matter right now.

When it comes to welding the ex. manifold it wont be a problem since i've done that type of work earlier, its more the basic design im looking for ideas of.

To list up things i would like to get some tips or pics of

1. Topmount or not

2. Waterlines

2. Oillines

Any other useful information/tips is really appreciated!

Thanks and cheers!

-David

[NYTSKY]

Give Jeffworld2 a PM.He has just finished putting twin GT-SSs on his 25

He is a friendly chap and im sure wouldnt mind answering some of your questions. But when there is a full moon....thats a different story!

[stricnynel0s]

  NYTSKY said:

Give Jeffworld2 a PM.He has just finished putting twin GT-SSs on his 25

He is a friendly chap and im sure wouldnt mind answering some of your questions. But when there is a full moon....thats a different story!

awesome look at my twin turbo setup on a 25

http://forums.nicoclub.com/zerothread?id=295315

[stricnynel0s]

  stricnynel0s said:

awesome look at my twin turbo setup on a 25

http://forums.nicoclub.com/zerothread?id=295315

ok for oil lines u did a 12x1.25 fitting to a -4 an for stainless lines with a 2 male 1 female t fitting for the oil feeds, for return its 3/4 bpst so u need to combine lines and thats block return for oil, now water is 14x1.5 (not tooo sure) u want -6 an lines from feed on block going to the front of the water neck there is a nipple thats what i am using for return any input ?

[NYTSKY]

  stricnynel0s said:

awesome look at my twin turbo setup on a 25

http://forums.nicoclub.com/zerothread?id=295315

Power figure??

List of engine mods?

[Jmaac]

Wont the Q45 max out? I would of thought the Z32 afm

[stricnynel0s]

  NYTSKY said:

Power figure??

List of engine mods?

engine mods are tomei valve springs, and oil orifice and metal headgasket, it has rb26 crank and been bored to make it 2.7, running a 740cc inj, power fc, and a custom intake manifold with velocity stacks, running stock r32 twin turbos until i can afford upgrade (wont be for a while) currently it does not run as its missing an assload of parts but it will be running by the end of the month

[jeffworld2]

hah twins are the go lately apparently.

i'm very happy with mine but all the same it could have been done with a single.... but we will leave that one alone for now

we basically split all the feeds at the block, and made an extra oil return and plumbed the water returns trying to keep everything away from the exhausts. im sure you could even bodgey up something with standard rb26 lines if you mount the turbos in a similar position. mine are low mounted and i could probably even get away with r33 gtr dumps/front pipe. in my opinion you may be better off switching to a gtr head and using gtr ecu, makes everything a bit easier and you get the better head and inlet too. i'm running a single afm so the piping is 'interesting' but works very well. a non-afm ecu would make that a bit easier on you.

one day i will take pictures lol. pm me if your after some specific info. it was not simple but is fun to drive. be aware that the exhaust is now 2x as loud lol despite the same catback

[stricnynel0s]

  jeffworld2 said:

hah twins are the go lately apparently.

i'm very happy with mine but all the same it could have been done with a single.... but we will leave that one alone for now

we basically split all the feeds at the block, and made an extra oil return and plumbed the water returns trying to keep everything away from the exhausts. im sure you could even bodgey up something with standard rb26 lines if you mount the turbos in a similar position. mine are low mounted and i could probably even get away with r33 gtr dumps/front pipe. in my opinion you may be better off switching to a gtr head and using gtr ecu, makes everything a bit easier and you get the better head and inlet too. i'm running a single afm so the piping is 'interesting' but works very well. a non-afm ecu would make that a bit easier on you.

one day i will take pictures lol. pm me if your after some specific info. it was not simple but is fun to drive. be aware that the exhaust is now 2x as loud lol despite the same catback

i did my oil differantly but water has me stumped, i got feed down just return is a pita, for freed i di da -4 an t from block with 2 -4 lines goin to banjo bolts on turbos

[brother_david]

Thanks for all your tips! Really useful ones, especially about the oil and waterlines so thank you both stricnynel0s and jeffworld2

Still waiting for the wheather to warm up alittle so that i can drive it safely to the garage, got it parked at my mothers place for now, not that safe parking it on the street outside my apartment

As soon as i got it in the garage i can start ripping it apart, and try to get a descent idea for the manifold design, have got some good ideas from your build stricnynel0s. Just talked to a friend who also build twins, but thats in a MKIV Supra aiming at a bit higher figures then me right now, anywas he promised to help me out alot so thats great!

Got a carmeet coming up in a month, can not decide whether to start building it before or after that though, wanna be able to show it, even if that means keeping the hood closed

Heres a pic i took 2 days ago, when i drove it to my mothers place, doesnt quite feel like the right enviroment, does it?

http://www.skylinesaustralia.com/forums/up..._829_128353.jpg

[PM-R33]

Out of curiosity, whats the RB25 like to drive on twin turbo's, lag wise i mean. Compared to a standard twin turbo RB26, noticable lag difference?

Edited March 29, 2008 by PM-R33

[GTRNUR]

+1 I'd like to know that too.

[RB SANDY]

+2

[Dale FZ1]

Looking at the difference in breathing efficiency through cam specs/timing, and compression ratio, I'd hazard a guess that there would be a reasonable (but not massive) spool advantage towards the 25. Perhaps 250rpm faster to hit max boost?

But then the 26 would make better power, continuing to produce torque as the revs climb.

The disadvantage with running stock 26 turbos would have to be (as usual) the ceramic turbines.

[Dale FZ1]

edit: double post.

Edited March 29, 2008 by Dale FZ1

[PM-R33]

  Dale FZ1 said:

Looking at the difference in breathing efficiency through cam specs/timing, and compression ratio, I'd hazard a guess that there would be a reasonable (but not massive) spool advantage towards the 25. Perhaps 250rpm faster to hit max boost?

But then the 26 would make better power, continuing to produce torque as the revs climb.

The disadvantage with running stock 26 turbos would have to be (as usual) the ceramic turbines.

I would have thought the RB26 would be more resposive; larger displacement, better flowing head with larger cams, 6 throttle intake etc. Only down side i can see is the RB26 having a lower compression ratio. However surely a RB25 would still be slightly laggier with twins? Any one that has experienced both cars know?

[jeffworld2]

ive still got vct going, and its fine driving around off boost. lag is a bit of an issue, but i have hks not stock turbos. power starts at around 4 and it screams by 5, but yeah you have to shift already around 7 whereas a gtr still has revs left at this level of modification. i would love a 26 head but its a bit late now

[stricnynel0s]

after reading this post

http://www.skylinesaustralia.com/forums/Rb...itting+on+block

i am lost as what to do about water returns, the feed is EZ, but i do not have thestock water linees, i am gunna run an-6 lines from a t fitting from the block as feed, and for return, i was gunna try the nipple on the water neck, should i use rear heater core hose, i also gotta get cooant to my iavc since i change the oil housing to the rb20 one

[Nismo_Boy]

Big power TT rb25 I had years ago. Photos are recent taken from the current owner, ignor the dust/dirt. New owner ditched AFM and went Djeto Power FC.

Oil and water lines were custom. Low mounted as it was more "stealth". Manifolds were factory cast GTR items that has the flange's cut off and re welded to suit the rb25 stud pattern.

Oversized forged pistons

Fully balanced

O ringed block

Major head work - Huge ports, a/m valves and springs ect ect

275 HKS cams

Custom cam gears

Greddy plenum

Q45 throttle body

100mm+ thick FMIC

GreddyBOV

Power FC

HKS 2530 turbos - Had them rebuilt using larger HKS 2535 wheels

HKS dumps

3inch front pipes

HKS 4inch super dragger exhaust

1000cc Sard injectors

300zx AFM (Might have been Q45, can't remeber)

Apexi pod filter

3/8 fuel lines

Malpassi fuel regulator

[rb26s13]

  stricnynel0s said:

engine mods are tomei valve springs, and oil orifice and metal headgasket, it has rb26 crank and been bored to make it 2.7, running a 740cc inj, power fc, and a custom intake manifold with velocity stacks, running stock r32 twin turbos until i can afford upgrade (wont be for a while) currently it does not run as its missing an assload of parts but it will be running by the end of the month

please for the love of god.. dont have it running untill you replace those stock r32 turbos.. they will let go on you easily