Rb30 Pre Build Advice

[raZ1911]

Hey guys

I been looking around and reading about the best way to make a RB30DET by looking at other builds and info on this site etc, i have 3 questions where i am just stuck on as i don't have enough experience.

I know the R32 RB25DE non VCT will go straight on., But will the RB25DE with VCT go straight on as well? (bar the fact that you have to drill some things to the block etc for VCT to work)

To me with not much experience in making RB30s etc this seems like the RB25DE with VCT head Vs the R32 RB25 non VCT will be a lot more expensive is this true? as i wont be doing it myself.

and lastly is it worth the trouble to connect VCT? I am wanting to run twin turbo system on this and im not sure if VCT is even worth the fuss?

Thank you.

Edited September 18, 2008 by raZ1911

[R34GTFOUR]

VCT is good for a daily driver and most will say its worth the effort (its not hard to connect, just a simple oil feed)

If you running big cams and big turbos and arent worried about the down low repsonse and cant be bothered hooking it up thats fine, a few people that have done the conversion havent connected it and its fine, but if you were running stock cams i would definately hook it up.

The rb25de vct bolts straight up the same as the r32 rb25de head, you just have to block the oil feed on the bottom of the head on the vct head, its all in the rb30 pdf though

[raZ1911]

Yeah i want the whole down low response thats why i want the RB30 haha

Yeah i read that RB30 pdf, was a good read. Just thought i would ask to be sure as i dont want to go out and buy a RB25DE VCT head then go damn its to much work.

So the RB25DE with VCT head goes straight on pretty much, just have to set up and drill a few spots for the VCT to make it run, other than that its the same as the R32 RB25de non VCT head from then on?

[TiTAN]

On the R32 25DE the cams are different (32 style to not suit VCT), the cas is different (again R32 vs R33), and you need to upgrade to GTR valve springs as the R32 25DE springs will start to give valve float with not a lot of boost.

[raZ1911]

Yeah i would definitely get the GTR valve springs eather head.

At what HP does VCT become pointless? due to other mods etc disabling it.

[TiTAN]

You can not use GTR valve springs in the VCT head, it uses different springs.

[bubba]

On the R32 25DE the cams are different (32 style to not suit VCT), the cas is different (again R32 vs R33), and you need to upgrade to GTR valve springs as the R32 25DE springs will start to give valve float with not a lot of boost.

Not necessarily true, my R32 25DE head made 365rwkw @22psi in it's old car with no float whatsoever.. stock cams and springs

Edited September 19, 2008 by bubba

[raZ1911]

oh didnt know that, seems a lot easyer to go the R32DE way lol.

what would be the springs to use for the RB25DE VCT head?

[R32Abuser]

it all depends on the car its going into...

R32-the R32 RB25DE head is the pick as its almost as simple as taking everything off your RB20DET and putting it on the RB30DET with no sensor etc etc changes

R33-then you'd obviously go the R33 RB25DE as you wouldn't need to change any sensors.

If you decide to put a 33 25de into a 32, you will need all the R33 RB25 sensors and the R33 RB25 ECU for the conversion to work....

the simple rule is:

Use the same ECU and sensors from or for the car you got your head from to make life easy

Price wise, you will pay more for an R32RB25DE head as they are rare as i got mine for 800, but a R33RB25DE would go for around 500

The R33 RB25DE also bolts straight on...bar the VCT work

Edited September 19, 2008 by R32Abuser

[raZ1911]

Yeah i have a RB20DET in the car at the moment. But i can sell / swap for RB25 parts that i need.

But if im doing it now i may as well do it right from the get go and keep VCT, as if i dont it would allways be on my mind.

As R32Abuser said about sensors and what not, Will keeping VCT make it more expensive to upgrade?

and is it true that you can use a remapped VG30DET ecu as it has VCT?

[R32Abuser]

Keeping VCT will only make it more expensive due to tapping to feed, and needing an RB25DET ecu to run it rather than your RB20 ecu that you have which can be remapped. Whereas teh RB25DET ecu cannot or is more difficult. As you said you can get a VG30DET comp to run the 33 head, but at the end of the day id personally rather go with a PFC.

If its going in a car which had a RB20DET, go with the R32 RB25DE head...trust me it will cause you less headaches in the long run. VCT isnt that great in the scheme of things, and if you ever want to do cams you lose this ability anyway.

[bubba]

Mucho easy to go in a 32 if you use a 32 25DE head. We did my conversion in a weekend and I drove it out of there at about 3am Monday morning on the stock ECU.

[raZ1911]

So if i dont go with the VCT head then im not missing out on much?

Because it seems like if i go with the R33 RB25de VCT head then i have to get the different set of side feed injectors, different ECU, sensors Loom, etc

Bit if i go R32 RB25DE then i can use loom, ECU, Manifold, exh manifold, sensors etc.

The only thing im worried about is low down power, Would i see much of a difference between a RB30 with VCT and without?

Im aiming for around 400 hp to 500 hp max, So would i most likely have to get cams in there anyway to achieve this so would going to all the bother of getting the R33 head on there be pointless?

[R32Abuser]

more or less going with the 33 head is pointless in a 32 unless you cant find a 32 RB25DE....

for example, Cubes makes 308kw with a GT30R, which gets full boost all in before 3000RPM i believe and a set of cams (you'll have to check with him on specs)...which is around the 420hp range. This is with a 32 RB25de from a R32. You would reach this power level without cams however you would require a larger turbo or larger A/R on a GT30 to push the appropriate flow, which lessens your low down response and is more ideal for higher end RPM power-something you don't want.

As what has been said, go with the R32 RB25DE. Its easier to fit in the car, and the small (read very small) gain to be had from using vct, is not worth the hassles you would have to go through to fit it in a 32/ceffy.

Edited September 22, 2008 by R32Abuser

[raZ1911]

Yeah i think i will just go with the R32 RB25DE head.

I created a list of everything i need, does this seem right:

1. RB25DE (R32) Head

2. GTR valve springs

3. Head Gasket

4. Inlet Manifold and Plenum (RB20DET)

5. grind down the water galleys protruding lumps that run from the front to the rear of the block.

6. Short Motor (RB30E Series 2)

7. RB30E Pistons (~8.2:1 CR)

8. Prepped stock rods

9. full length crank collar installed

10. Engine Bearings, (Genuine Nissan Bearings or better?)

11. Oil Pump RB20DET

12. Water pump & Thermostat (RB20DET)

13. Power steer bracket grind the lug flat so the bracket is able to sit flat on the block.

14. Use a longer piece of oil resistant hose for the oil drain pipe, you will also be required to bend and stretch the oil and water lines to meet with the turbo.

15. Gearbox RB25 Series 2

16. Relocate 33mm of tensioner studd

17. Cam Belt

[TiTAN]

3. not just the head gasket you will need all the new gaskets.

7. if you do go with forged pistons there are many options available however the CP 9.0:1 CR pistons are the normal recommendation.

8. for the price of prepped stock rods seriously consider the spool imports forged rods as they are not that expensive - see user spoolup on these forums

11. use an RB26 item or jun/tomei if the budget allows.

12. use a standard RB26 item.

14. if possible use a mostly metal oil return, the rubber/silicone drys out and cracks after a while due to the heat.

[bubba]

Yeah I wouldn't bother with prepping the stock rods, I am chasing a lowly power figure (300rwkw) for now which should be well within the realm of possibility for my stock RB30 rods. When I decide to chase more I'll be going for a set of Spool rods (and maybe even a stroker crank ).

[raZ1911]

stroker sounds nice!

So ill take out the prepping the stock rods i can do that later with more power.

For what would i need just to get the thing running and in the car without anything fancy does this sound right:

1. RB30E S2 block

2. R32 RB25DE head

3.Head Gasket (But what one just to get it running?)

4. Inlet Manifold and Plenum (RB20DET)

5. grind down the water galleys

6. stock RB30E Pistons (so for now the CR will be decent)

7. full length crank collar installed (do i need to do this?)

8. Engine Bearings

9. Oil Pump RB20DET (just to get it on the road)

10. Water pump & Thermostat (RB20DET) (just to get it on the road)

11. Power steering bracket

12. "Use a longer piece of oil resistant hose for the oil drain pipe" - will i have to do this with a stock RB25 turbo?

13. Relocate 33mm of tensioner studd and Cam Belt

14. RB20DET ECU - remapped

And that should get it running so i can drive it around for the time being (i wouldn't be driving it hard.)

[bubba]

I'm just running a new RB20 headgasket.

That will get you around driving, I drove mine for a few months on an ecu chip from a groupbuy (basically just had airflow cut and speed cut removed).

That said, you WILL max your airflow meter.. I maxed mine pretty quickly so when I went for a tune I threw a z32 afm and some 550cc injectors in there to make the most of the tune cost.

[raZ1911]

Yeah i have a Mines ECU in the RB20 at the moment.

But i think its best if i get some GTR injectors (when using the R32 RB25DE head?) and a AFM and tune it wit the stock ECU (not myself obviously)

The car I have is a 180sx with a RB20DET with a RB20DET box behind it, now i know its ok for the 20 box to go with the RB25 as its a lighter car than a 33 and such, BUT how long do you think it will last with the RB30?

Will it be ok seeing as though it is in a 180sx? (only for a short amount of time.)