My 25/30 Build, Before And After. Results!

[sriver killer]

Hey guys,

Just want to throw some results up on here. Its been a long 6 months spending only a couple of hours a week on putting this bad boy together.

Finally got it tuned and run in! I am over the moon with my results + the way she drives over my 25. The thing made 380rwhp on a measly 13 psi on first run, I was impressed!

This started off with an RB30 that cost me $200 bux.

For my Dollars, It had 90 thousand kms and I could watch it running in car. The oxy acetelene was then brought out and 40 mins later I had an rb30 Ready to Rock.

Boost cruising supplied me a $100 rb25 head that I got rebuild. Strangely enough I got it crack tested and valve stems/seats done and IT was in perfect running order to begin with.

Nothing has changed bolt on wise between my 25 and 25/30.

Using different heads, but still using stock cams. Only difference is that I did some minor porting (I think will do SFA) otherwise its still a pretty good back to back.

Please excuse though that my VCT is not working.

Not really sure how it works, the tuner said it is turning on and off. Though it is not advancing the cam? So There is better bottom end/response to be had.

I have to look into it more, ive got the internal vct mod with (I think ) 1.5mm hole from the hyd lifter gallery into the vct. Not too sure what troubleshooting that I can do from here.

Turbo is maxed out atm.

EGT's were considerably low, so she has got more in her if I want to upgrade.

Back to back with my 25 she isn't as prone to pinging and heat probably due to the compression ratio.

Absolute dream to drive off boost, I am glad I went to the 3076 not a 35R as this combination is just smooth.

Never looking back on my 25. HA.

All in all whatever you think your gonna spend DOUBLE IT. I build engines regularly, I went into this aiming for a budget build as it was my own I was incredibly anal.

So it copped alot of stuff that I otherwise would/could have got away with.

25/30

Ive done what I believe is the absolute MINIMUM for a reliable build.

Brand new 25 oil pump

crank collar (two grub screws)

Blueprinted complete bottom end.

Removed all casting flashes in block, crank, rods.

Polished, streamlined crank and rods

Balanced complete rotating assembly (including clutch and flywheel)

New cast pistons (standard pistons so 8.3:1 comp)

oil restrictors 1.5MM(both)

opened up oil returns

Nissan bearings

mls head gasket

arp head stud kit + rod bolts +resized rods.

std cams + my secret home port to the head.

Remove casting flashes, imperfections, port matched to both inlet and exhaust manifold.

CC combustion chambers,

Internal vct mod(vct isn;t working atm)

Helicoiled every single thread on the exhaust side. No more exhaust gasket leaks or broken studs.

Port matched inlet and exhaust manifolds.

6boost, , plazmaman, 3076R.82Rear ext gate and 3.5inch turbo back.

Took me 4 boxes of rings til I came across a set of rings that I was happy with.

First box was a set of NPR rings, had the best ring gap of the day.

Closer to factory rb30 na ring gap requirements rather than the 25 ring gap(larger) however I wasn't happy with the design of ring gap.

Hastings rings were visually the best quality/seemed to be best designed.

However, first box I opened was consistentely 10-12 thou larger than the npr rings. second box was even worse.

After my frustration of unwrapping my new clean block 3 times I hit it lucky on the fourth with a set of ACL rings.

the happy medium between the NPR and Hastings.

Can't beat cubes, I honestly didn;t think 500cc and a bit of crank weight would be such an improvement.

Still have to fix my VCT though.

Please find attached my rb25 dyno sheet and the current rb25/30 dyno sheet

cheers

[The Mafia]

Very well done mate. My build was exactly the same except reused the standard pistons and put a set of new turbo rings in them. Didn't check them anally like you did, as I'm not as experienced.

Anyway, it made awesome torque, but like you my VCT wasn't working. Had the same internal VCT mod. I also had 1.3mm restrictors though. Anyway, I got off easy and it was the VCT solenoid playing up. Once working, the extra torque on top of the 3.0L wow was even more!

Keep at the VCT diagnosis, there is a fair bit to be had with getting it working.

Once again, very well done. I think I spent about $2k all up rebuilding mine. But you're right - double what you think it's going to cost.

I'm happy to answer any questions you might have - hopefully I can help.

[sriver killer]

Hey mate, I cleaned the standard pistons and was going to get them crack tested.

For not much more than the crack testing I could buy new cast pistons so I went with them.

One thing I made sure I did when putting brand new std cast pistons in was use a ridge remover to get rid of the slight lip at the top of the bore (barely noticable even with a fingernail).

Just to ensure that nothing could bind when heat comes into the equation.

The tuner did say the vct is working, and he can switch it on and off, though it is not moving the cam.

Might swap that solenoid over, not too sure if it is going to help me much though.

I have to do some finding and find out exactly how it works.

Yer I blew my budget out of proportion.

I ended up spending the majority of the budget on getting the head done and machine work.

Haven't totalled it up tho I think I am hovering on the 3K mark. I certainly wouldnt do it for any less.

3K for a brand new engine is CHEAP, no matter how you look at it.

time to sort out the vct!!

[R32 TT]

I see you're using an interesting replacment for a cat there...

Adds a bit of bark to it does it?

[sriver killer]

He is helper number one,

My wing man on the sunday shifts:P

Does indeed add a bit of bark

[LightAssassin]

Hey Dan,

Saw you at the servo today. Car sounds great too.

Hope to see you on the track sometime, would be awesome to hear it at full swing.

Cheers,

Ben

[sriver killer]

No worries man! for sure give me the low down on the next time you go out

[Dale FZ1]

I cleaned the standard pistons and was going to get them crack tested.

For not much more than the crack testing I could buy new cast pistons so I went with them.

One thing I made sure I did when putting brand new std cast pistons in was use a ridge remover to get rid of the slight lip at the top of the bore (barely noticable even with a fingernail).

So you've used the standard bores? How did they measure up for ovalling or barrelling? I like the work you've done to make it all right, just not sure if there was a relatively important step missed by not having it bored.

Regardless of that, the results are impressive and give a good idea of what a quality fabricated exhaust manifold can do for efficient gas flow and power production. It's got to be a good thing to drive on the street?

I have previously noted the tendency for 30DET builds running stock cams to nose over by 6000rpm. This one seems the same?

[ST240]

Nice dyno graph and good info.

You say the turbo is maxed out. In what regard? It does look like power is nosing off at the upper end. Yet you say you're glad you did not go GT35R? Where then would you go if you wanted more power?

The reason I am asking is I'm trying to decide between GT30R and GT35R for my RB30. Mostly a street driver with a moderate amount of drag racing. If I can have the response on the street with enough power for 11s then I'd love to join the GT30R club too .

[sriver killer]

So you've used the standard bores? How did they measure up for ovalling or barrelling? I like the work you've done to make it all right, just not sure if there was a relatively important step missed by not having it bored.

Regardless of that, the results are impressive and give a good idea of what a quality fabricated exhaust manifold can do for efficient gas flow and power production. It's got to be a good thing to drive on the street?

I have previously noted the tendency for 30DET builds running stock cams to nose over by 6000rpm. This one seems the same?

New cast pistons were used in standard bores, reason being as it wasn;t much more in cost than an actual crack test on the piston/ I like brand new stock pistons over 20yo ones.

I measured the bores myself and were still within factory tolerance for std size pisons. No ovalling or anything giving me reason to rebore.

A ridge removal tool is necessary when doing this.

I would recommend though for the less experienced/underconfident people building their own motor to either re-use the stock pistons or go straight for the rebore( with pistons supplied)

Two ways of doing it, I wouldn't have done it this way if the motor that I had pulled apart had not been close to brand new!!

Awesome to drive on the street, yer seems to just get to thtat 6-6500 and has got no more puff

[sriver killer]

Nice dyno graph and good info.

You say the turbo is maxed out. In what regard? It does look like power is nosing off at the upper end. Yet you say you're glad you did not go GT35R? Where then would you go if you wanted more power?

The reason I am asking is I'm trying to decide between GT30R and GT35R for my RB30. Mostly a street driver with a moderate amount of drag racing. If I can have the response on the street with enough power for 11s then I'd love to join the GT30R club too .

We got to the point where it didn;'t want to make any more extra power without screwing alot of boost into it.

Don't quote me but I think from here on it it took another 5 psi to make only an extra 15whp or so.

So the extra hp didn't warrant the extra heat the turbo produced, as intake and EGT's went up.

The car is a handful already and has better street manners than my 25 just due to the delivery, add the torque and I simply do nto require any more hp.

Another thing I took into the equation was could I build an engine that would stay together and handle 400rwkw on stock pistons. And last 200,000kms +?

From here I would probably go back to a hypergear ATR43I. Back to back I had better results than my current 3076R

11's are easily achievable with a gt30R even on an rb25.

12.6 @ 119mph 2.1 60 foot on street kumho's with old dyno sheet above I am hoping to maybe do a low 12 tomorrow night at willowbank

[Slideways_Master]

hey man which stock pistons did you use 25 or 30's???

[sriver killer]

hey man which stock pistons did you use 25 or 30's???

Stock RB30 pistons are the goods mate

[sriver killer]

I wish I knew how to post that so you all you had to do was just click

[KiwiRS4T]

I wish I knew how to post that so you all you had to do was just click

You have succeeded - what kind of clutch are you running?- how does it hold up at the drags?

[sriver killer]

You have succeeded - what kind of clutch are you running?- how does it hold up at the drags?

I am a firm believer in the organic.

I am running a stock R33 gtst pressure plate, with an aftermarket gland in it with a shitload of clamp.

3200lb of clamp pressure. Using excedy organic clutch plate.

Alot cheaper/ easier to drive than any button/cushioned button. and its on par with the 10 inch plate clutch assembly that NPC offer(though not as light on the pedal)

Its done 3 years, prob about 50 1/4 mile passes, and gone through about 20 sets of rear tires. without slip!!!

I will never go button!!

[MRHD66]

How's the RB25/30 goin

[sriver killer]

How's the RB25/30 goin

Sweet as, treating her to a new sump as sump ventilation is one of the easiest things to overlook with a 25/30.

Getting rid of the hopes and dreams internal vct mod now goingto the traditional head feed, and slapping on a 35R for good times ahead

[MRHD66]

Sweet as I wanta do internal VCT on my RB25/30 how hard is it

[sriver killer]

Sweet as I wanta do internal VCT on my RB25/30 how hard is it

VCT is well worthwile having,

there is a thread on it here in the 30 section. works for some and not for others, this didn't work for me.

I would recommend people just use the traditional method of drill+ tap a front head feed. Because its a PITA to pull the head off again if it doesnt work for you.