Rb30det/tt Gtr Conversion Thread

[rev210]

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.

[sky30]

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

[R31Nismoid]

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

Being RWD lines are different to GTR conversions

[NissanFreak]

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

[rev210]

NissanFreak,

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

[NissanFreak]

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

[Turbz_13]

buy an os giken 3.0l bottom end

[rev210]

buy an os giken 3.0l bottom end

<{POST_SNAPBACK}>

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

[NissanFreak]

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

[[WLDCRD]]

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.

[manage13]

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?

[rev210]

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.

Edited February 18, 2006 by rev210

[sky30]

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

[TTT]

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

[Mr GTS4]

bring on the gts-4 4 door rb30 conversion

[FORZA-MOTORSPORT]

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

[Sydneykid]

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

2. Also, isn’t there a problem with harmonics?

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

[N I B]

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 job,5mm or so down the bore.

RB30 etc crank oil pump drive extensions are cheap in WA now, cheapest in the country and done very well.

Theres really not many down sides to RB30-25-25 engines these days as there well catered for now,I have had 2 gearboxes fail on the dyno in high output 30s but the OS cross mission gear set is lasting.

[Butters]

There are some straight answers I would like.

I am not building a RB30 but have seen a few issues semi answered that need to be cleared up I think.

So can anyone explain the following in-depth ?

Use a piston made for the job like CP and Arias.

RB26 piston sits way down the bore and thats very dodgy

Define "dodgy" ??

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 ?

Next one

1. Block mounted oil squirters can be fitted, but it is a bustard of a job and not all RB30 blocks are suitable.

Now the oil squiters still seem a mystery.

What makes one block "suitable" and another not SK ?

Has anyone ever seen or got pictures of Oil Squiters in an RB30 ?

[Sydneykid]

Now the oil squiters still seem a mystery.

What makes one block "suitable" and another not SK ?

Has anyone ever seen or got pictures of Oil Squiters in an RB30 ?

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, S1 blocks are not better (thicker/more consistent) than S2 blocks, N/A blocks are no worse than turbo blocks, Skyline blocks are no better than Commondoor blocks. Basically you buy 10 X RB30's and start measuring, only 1 or 2 will be suitable. It is still a bustard of a job to do, takes hours and a special jig, so very costly. Even then the result is not guaranteed.

My own RB31DET has oil squirters and no I am not pullng it out of the car to take photos. It doesn't look any different to RB20/25/26 oil squirters anyway, there just isn't the raised section where they bolt on.

We have built lots of RB30's without block mounted oil squirters, they show no signs of additional wear or damage when they are serviced. My suggestion, forget block mounted oil squirters in RB30's, ceramic coat the piston crowns, oil retention coat the skirts and move on.

cheers