First Rb30det Advice

[LRyder]

Hi Guys,

I am in the process of putting together my first Rb30det, and have spent hours reading the threads. I would like to here some of your thoughts on the setup I am planing to run.

Currently I have a

- r32 Rb25DE Head, which has been cleaned up, new valve stem seals, and equivalent GTR valve springs.

- 2x RB30 Blocks

- ACL rebuild kit (cast pistons over-sized, rings, bearings ect)

- All new gaskets

- Rb26 Oil pump

- Crank collar

Support mods include

- Rb25 GCG High-flow 14psi actuator (min psi it can run)

- Sard 650cc injectors

- Splitfires

- FMIC, 3" turbo back (no cat)

- z32

- Sard FPR

Drive train

- RB25 Box with 5 puck button Exceedy.

Tuned Via Nisstune ECU.

I am doing this on a budget, and can do alot of the work myself, I have all the support mods from my current RB20 set up (hence the RB25DE head). But I have heard the NA heads have bad flow and can be restrictive.

This engine will be used for hill climbs and drift, mostly drift, so I want a reliable motor.

Concerns:

- My power goal would be around the 250rwkw (please let me no if you think this is un-achievable), and would love 700nm + torque.

- Could my goals be achieved on a standard Rb30 bottom end? Or should I rebuild it with my cast pistons and new bearings?

- Also for my goal and intended use, is standard pistons ok? Or should I really consider forged?

- The small RB25 high flow turbo could also see as a restriction, choking up the exhaust side. Or power-band could be peaky to early, maybe unusable? Thoughts?

If you have any other thoughts or suggestions on my planed build please let me no your thoughts.

[R31Nismoid]

Do you have the GCG already?

If so, thats ok.

If not - 3076 or 3071 as stated (.82)

[LRyder]

stockies will do. but i wouldnt rely on your ecu.. any detonation and bang. you budget just doubled. since new turbos are all around the same price id go a nice gt3076. .82a/r

Yeh stock rebuilt? Like ACL, or just freshen up the old stock bottom end?

I will be going with a reputable tuner, and I no nisstune can be a limitation, but it does retain stock knock sensors. But yeh the stock internals doesn't leave much room for internals.

I would be planing to keep Revs below 7000 (along side all relivent oil control mods)

New turbo is really pushing the budget, but is something I am considering in future.

[LRyder]

Do you have the GCG already?

If so, thats ok.

If not - 3076 or 3071 as stated (.82)

Hey mate, currently running this turbo on my RB20.

Also trying to get my hands on an OP6 rear housing, which would be a cheaper option having it rebuilt then a whole new turbo.

[T04GTR]

stockies will do. but i wouldnt rely on your ecu.. any detonation and bang. you budget just doubled. since new turbos are all around the same price id go a nice gt3076. .82a/r

[TiTAN]

there isnt that much difference between a GCG rebuild and a new turbo. you will find the power peaks and is all over by 5500-6000 on the RB25 highflow.

[LRyder]

Will this turbo likely make 23-250rwkw? and alot of torque?

[TiTAN]

it will have a chunky power band from 1500 - 5500 more than that and there is so much exhaust gas that the turbo cant get rid of it and backpressure starts killing off all the power.

[LRyder]

it will have a chunky power band from 1500 - 5500 more than that and there is so much exhaust gas that the turbo cant get rid of it and backpressure starts killing off all the power.

This was one of my original concearns in my first post. Is there anything bar changing the turbo to help relieve this? A freerer flowing exhaust manifold (or porting out the stock manifold), heat wrap on the manifold and dump? , larger dump?

[R31Nismoid]

The turbine housing is the problem, a OP6 will make a minor difference.

You really need a turbo with a .82 rear IMO.

[sky30]

I wouldnt waste time building the motor with ACL cast pistons and rings. Stock rings are stronger, so id just use a stock bottom end (un-touched). you would be surprised how much power they will handle

I started with RB20 hiflow on mine and made 240rwkw, so you should do 250rwkw with the rb25 housings.

[LRyder]

I wouldnt waste time building the motor with ACL cast pistons and rings. Stock rings are stronger, so id just use a stock bottom end (un-touched). you would be surprised how much power they will handle

I started with RB20 hiflow on mine and made 240rwkw, so you should do 250rwkw with the rb25 housings.

Thanks mate, yeh I always have a spare bottem end to build up if somthing goes in this one.

Would it be worth just freshening it up? The bores are abit glazed, and new rings wouldnt hurt.

Also if I need to fit a crank collar the whole thing needs to come apart anyways. Thoughts?

[bubba]

If you're pulling it all down then make sure the crank is straight and has no end float, I didn't do that the first time and ended up having to pull the engine out, put new bearings and oil pump in. Cost like $100 to get the crank ground for oversize bearings.

[GT-RZ]

IMO when you have the block sat there you may as well hone it and fit new rings. minimum. i wouldn't want to use a worn 200,000k+ RB30 for my build. But +1 on using the stock rods and pistons rather than aftermarket casties.

You would be better off doing what bubba said too and fitting new bearings across the board while your at it.

[LRyder]

Thanks GT-RZ and Bubba thats most helpfull, I think I will freshen up the the stock bottem end, with new rings, bearings and hone.

Also looking at my turbo options.

Considering a 3076r .82 A/R, when does this turbo make full boost, and what kind of power would I make with this turbo. I would like it to be responsive, and maintain and beefy and linear power curve.

[GT-RZ]

Refer to this thread:

http://www.skylinesaustralia.com/forums/30...on-t285067.html

page 2 or 3 i asked almost the identical question you did. I'm leaning towards the gt35 twin scroll (1.06 rear housing) but have not dropped the idea of the 3076 with the 1.06 housing, not considering the .86 anymore though.

[LRyder]

Refer to this thread:

http://www.skylinesaustralia.com/forums/30...on-t285067.html

page 2 or 3 i asked almost the identical question you did. I'm leaning towards the gt35 twin scroll (1.06 rear housing) but have not dropped the idea of the 3076 with the 1.06 housing, not considering the .86 anymore though.

haha thats crazy, I just read that thread to only come back here for you to suggest reading it.

I think now for me is whether to go a Gt3076 but in .82 or 1.06. Very interesting read tho, I was actually going to refer to it here to see others thoughts.

I am also considering internalgate just for simplicity, cost, and stock look low mounted.

[GT-RZ]

have you considered the gt3082 1.06? seems to be the medium. If you want gt30 go the 1.06?

[LRyder]

have you considered the gt3082 1.06? seems to be the medium. If you want gt30 go the 1.06?

Oh I know! I looked at this also, sooo many options, I am just waiting for someone to sugest that in the previous thread.

[bubba]

I've gone for a GT3582R with a 0.82 exh housing, stock 25DE cams for now - will let you know how it goes in a month or two.. I'll be happy if it makes 1bar about 3000rpm and 500rwhp!

Edited August 30, 2009 by bubba