Rb30det/tt Gtr Conversion Thread

[Bl4cK32]

I have also read that if you deck the block then 25/26 pistons work well .... is this true ??

What comp ratio do you roughly end up with when using RB25det pistons ?

Cubes and i are using Wiseco rb25det pistons in our rb30det. They decked the block (20 thou?), and added a 3 layer metal head gasket, and compression works out to around 9:1 if Cubes' calculations are spot on

Oil squirters are overrated. Do like SK says, ceramic coat the pistons etc if you run cast ones, or just run forgies and dont worry about it

Having a piston sit down in the bore is dodgy, because its supposed to end its stroke flush with the top of the block. Otherwise compression, squish etc are all off.

No one has mentioned about the rb26 head having larger head studs that the rb25. You need to retap the rb30 block out to bolt the rb26 head on.

[FORZA-MOTORSPORT]

I am still wondering about the SUMP adaptor, cant u just use the sump from the GTR/GTS4 on the rb30? U might have to modify it a little? Also is it ok to use a VL turbo headgasket with the 25de head? If not will an rb25det metal headgasket do the job?

[TTT]

I already mentioned in this thread who makes the sump adapters.

yes you can use the RB30 gasket.

you can buy a VRS gasket kit which has all the gaskets for everything.

[Sydneykid]

I am still wondering about the SUMP adaptor, cant u just use the sump from the GTR/GTS4 on the rb30?

The bottom of a RB 2wd block looks nothing like the bottom of an RB 4wd block. The 4wd block is much wider, has many more and much larger diameter bolt holes. As you would expect to hold up a big diff, drive shafts and large cv joints for the front drive.

cheers

[FORZA-MOTORSPORT]

Yes well i am a noob to this, so feel free to drill me all you like . Well if a sump adaptor has to be used then ill have to get one, the guy that sells these on the forum does he answer his pms? Its just i hope to have my motor finished by sunday and hence ill need the adaptor before i can put it in next week so id like to get it kind of soonish... Also how many are going with a custom plenum to solve plenum hitting bonnet problems? If you do modify the engine mounts to suit then wont the gearbox and everything else be out and be under a lot of stress, hence why i am just getting a custom plenum top $200 bucks let me know if anyone else needs one.

Sorry to ramble so much in the one post but i have a few more questions . Which turbo would be ideal for this motor Gt3540, injectors GTR 440's, Q45 TB and Q45 AFM? At the moment i have a HKSGT2510 which would make it more like a supercharged 25/30 :lol:

Edited February 24, 2006 by FOOLBOOST

[Bl4cK32]

ok, well i'll point out if you are doing the rb26/30 conversion, you would be using the rb26dett head, which already has the front facing plenum from factory.

gearbox etc, can be spaced down the same amount the engine is dropped, but ive been running my car without doing it with no vibrations, or problems.

Turbo, i suggest whatever power you wish to strive for with the supported mods. Gt2835r or upwards (gt30r minimum), and a longer diff ratio.

25/10 is way too small like my turbo. On boost its useless, just wheelspin.

[Butters]

The castings are slightly different, the oil gallery that the squirters have to be tapped into has variances in its diameter and the wall thickness varies as a result. I have found no common ground

Thanks SK, mystery resolved.

no I am not pullng it out of the car to take photos

lol ..... and why not ??? no help internet people of today :lol:

Cubes and i are using Wiseco rb25det pistons in our rb30det. They decked the block (20 thou?), and added a 3 layer metal head gasket, and compression works out to around 9:1 if Cubes' calculations are spot on

Cheers black32

I am suprised it works out so high comp wise as the extra CC in the head drops the comp a bit from what i understand.

Just to confirm you decked the block for the sole purpose that the pistons sit to low ? and not to gain comp ratio ?

[Bl4cK32]

Cheers black32

I am suprised it works out so high comp wise as the extra CC in the head drops the comp a bit from what i understand.

Just to confirm you decked the block for the sole purpose that the pistons sit to low ? and not to gain comp ratio ?

Cubes is the details man, more of a memory than i

Bit of iffy area about what our comp ratio works out to be, as the engine builder worked it out to around 8.5:1, but cubes says he worked it out to be 9:1. And going by somethings (like the amount of timing we run ?) he seems to think it may just be.

[N I B]

The correct piston is avalible so why not use them.CP and Arias are on the self(Rocket have sold out of Arias but in stock again soon)

[Guilt-Toy]

i know this is a bit off topic but i have got a sump / front dif setup for a rb25 stagea if anyone is interested in buying it pm me.

[Fitzpatrick Speed Works]

Hi all,

My adapter plate allows you to bolt the rb26 sump to the rb30 block. It is CAD designed to match the rb30 block to the wider 4wd sump. However there are other mods that have to be done besides just the adapter.

After that you will have to fabricate an external oil pickup due to the different pickup locations for a rwd rb series engine and a 4wd engine. You will also need to lastly modify the studs on the cv side of the sump to 2 long bolts, and also die grind or mill flat a part of the rb30 block to allow bolts instead of the studs on the diff side. This all sounds hard but i provide detailed instructions on how i did it and how you can do it, and if you are mechanical you can do alot yourself, I have done around 6 know and have sold many plates. This aside i sell the bare plates laser cut from cadium plated mild steel for $450, and if you got the rest done at a workshop it would cost no more that $4-600 in labour. So total cost is around the 1-1.2g mark, which is very competative considering RIPS will not do the job without selling you a built bottom end for $3800, and NIZPRO and AVO will not do it with out your own motor and sump sent to them and they charge $4200, theres is slightly different but I also offer different versions of tha adapter, however I am not bagging these workshops they do good work, but if you are a DIY'er then my setup is perfect for saving some money and getting involved.

If you have anymore questions please dont be afraid to ask. But i don't really want to give out pics and detailed instructions just yet when it took me so many r and d hours to work it out for myself, like i said the other guys that do the conversions wont even sell the plate seperate cause they dont want to give away secrets!!! But like i said if you have questions about the process of fitment please dont hesitate. The plate i sell is straight forword and guys out there could make one themselves but it takes time to get spot on, and most people would rather buy soemthing they know has worked ad yeah I am not in this to make money so i basically sell the plates for what they cost me.

Cheers,

Daniel

Oh and FOOLBOOST if you want to chat give me a call on 0418 327 427, not on the computer much anymore so dont get to check my pm's.

[FORZA-MOTORSPORT]

Guys i have now got a problem cant find an r32RB25de non vtec head, so looks like i will be going rb26 this will also solve the bonnet/plenum clearance issues. Was wondering what mods have to be done to the stud holes with regards to being smaller? Also will it be a nitemare to setup the inlet plenum throttle linkages and wiring to go to the rb26head? I am also thinking of going single turbo if i can get a single turbo manifold or is twins better would be much easier since id be getting the twin manifolds with the head anyway???

[N I B]

26 head is easy.Get your machine shop to tap the block for the bigger studs,linkage mounts up very close to the same but the 25 cable is longer so it looks ugly looped so just use a GTR cable.Over all the 26 head is easyer then the VVT head.

[FORZA-MOTORSPORT]

Have located an rb26 head with plenum and exhaust manifolds complete 1500 apart from injectors, cas and ignitor. Now can i just bolt on an r32rb26 head with mods to the bolt holes and use my gts4 injectors, cas and ignitor and power fc??? Then i will have to locate twin turbos or run a single if i can find a single turbo manifold!!

[FORZA-MOTORSPORT]

Ended up getting a complete r32rb25de non vvt head with injectors coil packs, manifolds etc $500. Have finished bottom end pistons and crank, just waiting on metal headgasket and head goes on. I have also just received one of daniels sump adaptors nice piece of work! Now all i will be left to do next is modify the bottom end to suit the 4wd and relocate the oil pickup etc does anyone sell these already done??

Edited March 7, 2006 by FOOLBOOST

[FORZA-MOTORSPORT]

Heads on, ran into the problem of the exhaust manifold touching the block, so have decided to grind the manifold down rather then the block. Also just bought a GT3540 with 1.06 rear AR hope thats not too big or i will be changing to .82 soon if its too laggy. Will be making a custom adaptor plate to standard manifold which runs an external wastegate along with custom dump pipe, ill post some pics up.

[FORZA-MOTORSPORT]

My 25/30 motor is finally finished and there seems to be one thing i have overlooked, it says to grind down the webbing in the sump on the rb26 sump, since i am using a 10mm sump adptor plate will i still need to grind the webbing down?? I need to know asap as the whole motor is finished and i want to make sure the rods arent gonna hit on the bottom of the sump??

Edited April 2, 2006 by FOOLBOOST

[Fitzpatrick Speed Works]

Ive never had to grind any webbing on the sump itself. I assume you mean for the webbing to clear the cross member? IF so you dont need to it doesnt touch!!

[BlownNBoosted]

i just got my RB26/30 engine back from my engine builder and was wondering what people do for oil and water feeds for turbo's, i am using a high mount twin setup if that makes a difference

[FORZA-MOTORSPORT]

rb20/25 sumps have webbing towards the rear of the them which has to be grinded down otherwise rod cap will hit, rb26 sumps dont have webbing so dont have this problem! What the hell do i do with the gearbox since the top 4 bolts line up but the bottom 4 dont any ideas??? Thinking of just using the top 4 and leaving the bottom ones out