Jump to content
SAU Community

Recommended Posts

What an awesome thread! I thought that 10 page pdf was impressive but damn!

Im building an rb30/25 and have got the block almost ready to put into my 32 coupe. The parts used in the block are as folows:

-Rb30e block

-Factory crank (re balanced)

-Wiseco forged pistons (40thou oversized)

-Forged eagle rods

-N1 oil pump

-ACL race bearings (big ends and mains)

-ARP bolts

The block was honed bored decked and acid dipped and now is back in my possession.

Ive bolted up the mounts, sump, water pump and flywheel and it is about to go into the car. BUT only recently ive heard i should restrict the oil flow to the head using TOMEI gallery restrictors so the blocks oil isnt pumped all to the head.

Is this a necessary and recommended mod?

My next querie is will I need to replace the factory rb25de valve springs to cope with big boost? With the block ready to make mumbo i dont want the head to restrict me too much!

Any tips would be awesome

Cheers xsv 32

Um thanks but im from christchurch new zealand lol. Anyone know how to tell the difference between a r32 and r32 rb25de head??

the r32 doesnt have vct and has smaller ports afaik, the springs should be the same as any rb25 non neo (aftermarket wise)

Edited by R34GTFOUR

R32 RB25DE non VCT has different springs to R33 RB25 VCT - they are same as RB20 or RB26, equal length on both the ex and in so you can not use R33 ones.

the r32 doesnt have vct and has smaller ports afaik, the springs should be the same as any rb25 non neo (aftermarket wise)

Awesome. Im pretty sure its a r32 25de head which is perfect bar the weak springs...

Was just masking up the block to paint and discovered that the engine builder had already put oil gallery restricters in for free! SCORE. :)

Any suggestions on the best gasket to use? The block and head have only been surfaced and not skimmed so what thickness should i aim for to get around 8.5:1 - 9:1 compression.? Also the pistons are oversized about 1mm...

Based apon my thread named "Which RB engine combo?"

I'm looking at building a performance RB motor out of the bits and engines that I already own.

Here is the list;

RB30 engine (non turbo) complete

RB25DET complete (worn rings)

RB26DET rods and pistons (only)

Do I start with my RB25DET engine and work it or the RB30 and work it and say put the RB25DET head on it? Surely I dont have to use the RB25DET head on the RB30 to get 300plus rwkw? I know the RB26DET rods and pistons fit into the RB25DET but do they also fit into the RB30 crank and block as they are all the same bore size? Im not wanting to spend to much money but prepared to spend some money of course for extra performance bits. I'm wanting to get as much hp as possible and still use pump fuel and have boost under 20 psi.

Any other suggestions?

The engine will be going into a 1970 fibreglass car (total weight 750kg) that has no loom for these motors so I may consider a carburrettor version of the above or obtain the appropriate loom/computer.

________________________________________________________________________________

______________________________________________________

My latest thoughts

Ok...why cant I just use a standard rb30 head (maybe port the head a little) on my rb30 block? What benefit am I really going to get putting my rb25 vvt turbo head on to the rb30 block with all the head ache and modifications needed to do so?

Surely the rb30 head with some work done to it can do the job as well or better? The rb25 vvt turbo head is probably worth $700-800 at then I still have to change 2 cams in it costing probably $1500 plus in total. I only have to buy 1 cam for the rb30 head?

So...the rb26 turbo pistons fit on to the rb30 rods and can then be used into the rb30 block. What compression ratio will this give me using the rb30 head?

Edited by The Ant
Surely I dont have to use the RB25DET head on the RB30 to get 300plus rwkw?

The idea of the 3ltr is it spools a larger turbo quicker and makes more power 'under' the 300rwkw curve.

An rb20det can make 300rwkw but it will be as laggy as hell and have bugger all mid range.

I know the RB26DET rods and pistons fit into the RB25DET

The rods fit but the pistons will NOT unless you also run with the rb26dett crank.

The rb26 gains its additional 100cc by using a slightly longer stroke and pistons with a reduced pin height. Drop 'just' the rb26 rods and rb26 pistons in to an rb25det and the comp ratio will suck not to mention the piston sitting down the bore. So definitely not a wise move.

but do they also fit into the RB30 crank and block as they are all the same bore size?

No the rb30 has a longer stroke and rod length. So no. :blush:

Ok...why cant I just use a standard rb30 head (maybe port the head a little) on my rb30 block? What benefit am I really going to get putting my rb25 vvt turbo head on to the rb30 block with all the head ache and modifications needed to do so?

Surely the rb30 head with some work done to it can do the job as well or better? The rb25 vvt turbo head is probably worth $700-800 at then I still have to change 2 cams in it costing probably $1500 plus in total. I only have to buy 1 cam for the rb30 head?

You can but the rb30/25 will ALWAYS make the power easier and be much more fuel effient and friendly to drive.

Start working the sohc head with big cams to get near the stock flow level of the rb25det and fuel economy/driveability suffers.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • Had I known the diff between R32 and R33 suspension I would have R33 suspension. That ship has sailed so I'm doing my best to replicate a drop spindle without spending $4k on a Billet one.
    • OEM suspension starts to bind as soon as the car gets away from stock height. I locked in the caster and camber before cutting off the kingpin. I then let the upright down in a natural (unbound) state before re-attaching it. Now it moves freely in bump and droop relative to the new ride height. My plan is to add GKTech arms before the car is finished so I can dial camber and caster further. It will be fine. This isn't rocket science. Caster looks good, camber is good, upper arm doesn't cause crazy gain and it is now closer to the stock angle and bump steer checks out. Send it.
    • Pay careful attention to the kinematics of that upper arm. The bloody things don't work properly even on a normal stock height R32. Nissan really screwed the pooch on that one. The fixes have included changing the hole locations on the bracket to change the angle of the inner pivot (which was fairly successful but usually makes it impossible to install or remove the arm without unbolting the bracket from the tower, which sucks) and various swivelling upper arm designs. ALL the swivelling upper arm designs that look like a capital I (with serifs) suck. All of them. Some of them are in fact terribly unsafe. Even the best one of them (the old UAS design) shat itself in short order on my car. The only upper arm that works as advertised and is pretty safe is the GKTech one. But it is high maintenance on a street car. I'm guessing that a 600HP car as (stupidly, IMO) low as you are going is not going to be a regular driver. So the maintenance issues on suspension parts are probably not going to be a problem. But you really must make sure that however your fairly drastically modded suspension ends up, that the upper arms swing through an arc that wants to keep the inner and outer bolts parallel. If the outer end travels through an arc that makes that end's bolt want to skew away from parallel with the inner bolt, you will build up enormous binding and compressing forces in the bushes, chew them out and hate life. The suspension compliance can actually be dominated by the bush binding, not the spring rate! It may be the case that even something like the GKTech arm won't work if your suspension kinematics become too weird, courtesy of all the cut and shut going on. Although you at least say there's no binding now, so maybe you're OK. Seeing as you're in the build phase, you could consider using R33/4 type upper arms (either that actual arm, OEM or aftermarket) or any similar wishbone designed to suit your available space, so alleviate the silliness of the R32 design. Then you can locate your inner pivots to provide the correct kinematics (camber gain on compression, etc).
    • The frontend wouldn't go low enough because the coilover was max low and the upper control arm would collapse into itself and potentially bottom out in the strut tower. I made a brace and cut off the kingpin and then moved the upright down 1.25" and welded. i still have to finish but this gives an idea. Now I can have a normal 3.25" of shock travel and things aren't binding. I'm also dropping the lower arm and tie rod 1.25".
    • Motor and body mockup. Wheel fitment and ride height not set. Last pic shows front ride height after modifying the front uprights to make a 1.25" drop spindle.
×
×
  • Create New...