My Rb25/30 Build

[works 510]

At the moment I'm fairly bored, and my internet is capped so why not put up a build log.

It all started with the good ol' RB20DET that came factory in my cefiro, un-tuned with a hks 2535 bolted to it running 12psi, it was good fun.

Motor was abit tired, got offered a cheap rb25det, did the conversion.

At the same time, the matching 5 speed went in.

After sorting out a heap of bugs, and a missfire issue that was sorted by going the AU falcon coilpack route I took it on its first decent run.

About 1.5km's from where its stored, it decided to lean out and kill No 6 piston. Yay.

Im still not sure how it happened, as the car was under next to no load and I was doing 50kmh in a residential area..

Regardless, here I am now, accumilating bits for the rb25/30 build.

At first I was just going to grab a bottom end, re-ring and bearing it, use my old turbo setup, tune and have fun.

After reading through this section numerous times, talking to a few people etc, ive decided on a decent build, without killing my bank account.

Heres a run down:

R33 DET head, modified vct as per "psi"s thread. (this was way easier than I thought)

Stocking porting, stock cams, new guides and valve stem seals, mainly due to it really needing guides.

I cleaned up the oil returns in the head.

Block tapped for new tensioner, both vct and tensior mod done in the garage.

Block bored .20 to suit mahle 8.5:1 CR pistons.

Restrictors fitted.

spool rods, I know nissan stuff is good (dont have a worry with L series nissan rods) but by the time I added up resizing the

rods, balancing and rod bolts, a couple hundred more gets spool rods.

Crank grubscrewed and machined for collar.

N1 oil pump. Haha. I know there has been alot of talk about them recently, Im thinking about either going the gears from JPC or hanging out to see results from the splined oil pump drive idea.

Ross Balancer, still need to get one of these.

Bearings, unsure of what to use there

ACL rb30 metal head gasket.

headbolts, unsure again. Might just get some new nissan bolts.

Sump is still standard, not sure what to do, a aftermarket ones kill's my bank account.

Turbo is a IHI C7, its large, plain bearing and has some sort of weird V-band rear on it.

Highmount stainless manifold, trust wastegate.

Not a whole lot of info on the IHI, only thing I could find that the RX6 superceeded the C7.

Measurements say its inbetween the gt30 and gt35.

480cc jdm s15 injectors, big enough?

greddy style inlet, stock throttlebody.

(Also have a complete rb26 throttlebody system here thats had injector bungs welded to it running a extra 6 injectors on a rail, no idea on injector size until I get one tested. I was thinking about using the rb26 stuff but have no idea on what to do, loom wise)

Ecu: z32 remap

Possibly I few other things ive forgotten.

Goal: 300rwkw, max reliability.

Any other idea's, thoughts or corrections you guys might have are welcome

[Dale FZ1]

How hard are you going to rev the thing? Leaving cams and ports stock won't stop you making the power target, but would put a ceiling on rpm where it starts to flatten out.

Might be overkill and overspending on the rods and harmonic balancer if your target is going to be achieved under 7000rpm.

Those S15 injectors actually flow 450cc at std rail pressure, so not likely to do the trick for 300rwkW unless you play with FPR.

[works 510]

Rev-limiter was going to be set at 7000.

Rods and balancer was just a do it once,do it right kind of thing, as no doubt i'll be hunting down more power in the long run.

When does the quest for power ever end?

Balancer mainly to try keep the N1 pump alive, and my stock one isnt in very good condition.

FPR, I have one around here somewhere, its fairly old though and doesnt have a pressure gauge built into it.

[CEF11E]

my 740cc injectors are running 72% duty cycle at 310rwkw with lots of load. so you might need a set of 550's.

there are a lot of people using smaller but at really high duty cycles.

My injectors are 370cc standard purple tops I have hiflowed. I have done about 7 sets now and have had 100% success rate with them. they are difficult to get cold start right but they are fine after 15 seconds of driving.

the pintles are machined then you ultrasonically clean them and replace the pintle caps and flow test them.

cheers!

[bubba]

Definitely get a decent sump dude, I went with the ASR RB30 sump from Justjap.. it was basically a High Energy Pro-circuit sump without the High Energy pricetag.

[works 510]

Might aswell update this thread.

Have been slowed down by my machinist who just brought a heap of new machines for the shop, so work over the xmas holidays till now had stopped.

Which sucks, I want my car running!

Got in contact with CEFF1E, got some hi-flow 740cc injectors done by him.

Seen his personal car run, spoke abit of crap, nice guy.

Had a good think about oil pumps, ended up putting a order in with jpc for their aftermarket N1 pump gearset after going in there for a chat and to look at some VLt's.

Asr s/c sump purchased.

Decided to ditch the vct and run rb20 cams and timing covers, mainly for the fact some big cams will be fitted later on and I want to retain my "RB20" top timing cover.

Slowly getting there, spare funds pending.

[ST240]

Thats a budget build? o_O

My previous engine was RB20DET as well. I was considering fitting the RB20DET cams in my RB25DE head... What differences in performance would one see by doing this?

Edited February 24, 2010 by ST240

[works 510]

Well, depends on what you define as budget.

A large majority of the parts were sourced from the usa, motor assembly will be done in the shed.

maybe call it a medium budget build? haha

it sort of snowballed (this tends to happen) with the main cost factor was the oiling system as I wanted reliability as the car will be finally entered into comp drift and not just a street bomb anymore.

As for the cams, probably no gain at all, it was just a way of making the motor more simple, and maybe abit more cost effective now i can just run one of the few r32 gtst ecu's I have lying around insted of going the z32 ecu path.

Plus retaining the rb20 timing cover and putting me in the position of bolting in big cams when some good price secondhandies are found.

[bubba]

Thats a budget build? o_O

My previous engine was RB20DET as well. I was considering fitting the RB20DET cams in my RB25DE head... What differences in performance would one see by doing this?

I had an engineer at work look over the specs of 20DET and 25DE cams, he said I'd be losing a little bit of power with the 25DE cams.

I think the main difference is less overlap on the turbo cams and possibly slightly more lift (been a while since I looked at the specs).

[MBS206]

I had an engineer at work look over the specs of 20DET and 25DE cams, he said I'd be losing a little bit of power with the 25DE cams.

I think the main difference is less overlap on the turbo cams and possibly slightly more lift (been a while since I looked at the specs).

If you're running a 25DE head, make sure you change the valve springs as the 25DE springs are soft, and do not like boost.

[bubba]

If you're running a 25DE head, make sure you change the valve springs as the 25DE springs are soft, and do not like boost.

The head I've got is maybe 7,500km old and with stock cams and springs (albeit new), made 365rwkw @ 22psi (with no sign of valve float) in the last car it was in.. so I think they should be fine

Edited February 26, 2010 by bubba

[ST240]

Yeah ive heard of guys having issues with valve float so i have a set of gtr valve springs on the way. $100 bucks is cheap insurance.

With regards to the cams yeah i saw a pic on here somewhere you can definately see the 25DE cams have more overlap. Maybe ill fit the 20DET cams then . The flip side is ive seen good results on the 25DE cams too. Can anyone else comment? (not to hijack your thread )

[MBS206]

Yeah ive heard of guys having issues with valve float so i have a set of gtr valve springs on the way. $100 bucks is cheap insurance.

With regards to the cams yeah i saw a pic on here somewhere you can definately see the 25DE cams have more overlap. Maybe ill fit the 20DET cams then . The flip side is ive seen good results on the 25DE cams too. Can anyone else comment? (not to hijack your thread )

I run an R33 RB25DE head, valve floats about 6500RPM with 1 Bar of boost on my turbo (Big mean mother trucker).

I also run the R33 25DE cams, the car "makes" 250RWKW... BUT this was on a dyno there was complaints the following day of ultra low readings, add to the fact no matter what we did it wouldn't stop wheel spinning above 5000RPM...

[[200]]

I had a look on the Nissan Fast software and the valve springs from the rb25de, rb25det and rb26dett have the exact same part number. Unless I am doing something wrong...???

Edited February 28, 2010 by [200]

[MBS206]

I had a look on the Nissan Fast software and the valve springs from the rb25de, rb25det and rb26dett have the exact same part number. Unless I am doing something wrong...???

Nearly everyone with a 25DE has found them to be soft.

I have a set of 25DET springs in my room, when I pull the head off my 30 I'll compare the springs from the 25DE head to them.

Edit; And when I checked with the guy at Nissan he mentioned different part numbers for them.

26DETT should DEFINITELY have different valve springs.

[fletch rb30]

I compared a set of r33 25de and det springs and they were identical height and spring rate

[Cartman]

rb26 definately have different valve springs, r33 rb25de and 25det wouldnt suprise me if there the same as they are both VCT, r32 rb25de are different again tho as these are the heads people were experiencing soft valve spring problems with, non vct head. from memory anyway haha

[[200]]

Nearly everyone with a 25DE has found them to be soft.

I have a set of 25DET springs in my room, when I pull the head off my 30 I'll compare the springs from the 25DE head to them.

Edit; And when I checked with the guy at Nissan he mentioned different part numbers for them.

26DETT should DEFINITELY have different valve springs.

See attached, identical part numbers. It seems as though the rb26 has the same part number for both inlet and exhaust springs compared to the rb25's.

And the R32 RB25DE has the same part numbers as rb26dett

Edited February 28, 2010 by [200]

[ST240]

Wow what the deuce?! Can anyone confirm or deny this?

Everywhere I've read people are talking about valve float with the R32 RB25DE head. Certainly it can't have the same springs as the RB26DETT?

[bubba]

Wow what the deuce?! Can anyone confirm or deny this?

Everywhere I've read people are talking about valve float with the R32 RB25DE head. Certainly it can't have the same springs as the RB26DETT?

Not everyone.. my R32 RB25DE head with stock cams and springs handled 22psi with no valve float, maybe if they were old and tired..