I know we have our lovely and very huge thread on the RB30 conversion already.


However the Rb26/30 GTR conversion has a few more bits and peices to make this process work.

How about we have a thread specific to the GTR conversion that covers:

* the Rb26dett head build up to suit
* Forged piston selection Vs compression
* Sump adaption and oil pick up.

A step by step pics based guide for DIY would be great to eventually have too, for anyone thinking of doing this in the near future to consider adding to this.

Saves wading through the hundreds of posts.

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Im also interested in some info on this topic, im soon to do the conversion.

Once this thread gets detail, ill add to the FI guide.

Being RWD lines are different to GTR conversions

Ok here are some for starters.

1) Sump/Diff Adapter: There are people offering these but they take alot of work to fit/line up. Chunks of the block on the diff side of the sump ie webbing needs to be removed to clear the studs from the sump.

2) Head fits straight on as per normail RB26/30 engines, only thing I recommend over and above the normal modifications is the additions of a oil drain back from the rear of the head to the sump.

3) Oil Pickup, im sure there are a few methods but due to the oil pickup on the RB30 being too far back this needs to be blocked and then be tapped into from the outside of the block, the pickup on my engine is boxed and mounted to the base of the sump with a line running to the turbo side of the engine/sump. this is then connected to the oil pickup tapped from the outside with an inline filter.

4) Compression ratio on mine is close to 9.0:1, by using positive RB26 CP pistons.

Hope this helps as a starter.

NissanFreak

NissanFreak,

Good starter. Do you have any pics of the sump issue?

REV210 Will try and arrange some, my engine should be done late next week

buy an os giken 3.0l bottom end

my 2c for you is start your own thread about os giken.

OS Giken from what I have seen has its own issues, only benefit is a fully counterweight billet crank which you can get for $6000 no need to spend $30000

NissanFreak

i am pretty sure i read somewhere that the OS 3L uses the N1 block. They then bore it out and i think it gets sleeved although i cant be sure on that. I asume you are talking about using an RB30 bottom end to create the base hence the sump adaptors and the like. There was a shop mentioned on here ages ago that talked about creating an RB26/30 using an existing normal RB26 block, then boring it, sleeving it, and then decking it to create the extra 0.4L capacity. But i dont think they ever did it in the end.

With regards to the RB30 or 31 bottom ends how do you go about putting the oil squirters in?

Also, isn’t there a problem with harmonics?

I will add a FAQ part to the first post to address the questions like ;

What about harmonics on the RB30? etc...

If we can keep to the Actual experience, images and advice of those who have built and fitted the Rb26/30 to a GTR that would be good.

Oh and specualtion about the OS-giken and other capacity enlargements can start another thread as this one concerns the RB30 conversion only.

Anyone got any more info on the RB30-GTR/GTS4 conversion?

I'm sure he'll see it but it might be good to point htis thread out to user "Fitzpatrick Speed Works" who makes the sump adapters.

also SK will probably have good input to this too.
I'm keen to know this aswell for my gts4

bring on the gts-4 4 door rb30 conversion

Hi guys doing the 25/30 conversion to my gts4 at the moment and wondering about the sump adaptor? Does anyone on the forum sell one? How much modification is required and does it bolt straight on

cheers,
Ant

1. Block mounted oil squirters can be fitted, but it is a bustard of a job and not all RB30 blocks are suitable. For temperature control, ceramic coating the piston crowns and oil retention coating the piston skirts works very effectively and costs less.

2. Grossly overrated, same bore and stroke as a 2JZ, never hear about harmonics in them. Proper balancing goes a long way and the block strength added by the 4wd sump adaptor helps as well.


cheers

Just make sure no one sells you RB26 pistons as RB30 twin cam pistons as many companys do.Use a piston made for the job like CP and Arias.
RB26 piston sits way down the bore and thats very dodgy.
We are building 30s now using CP pistons that are made for the job and their working very well.Ross is one piston thats sold as an RB30-26 piston that is really an RB26 piston and its a long way from the right piston for the j