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Na Rb26/30 Built .....help Need

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I'm running 25DE pistons that have been shaved, also had the block shaved and the head leveled I think from memory. When it was all said and done the compression ratio was over 12:1 which is so border line having to run race fuel (something higher than 98 - 100 octane at least anyway) that on a hot day here in Australia it would ping. I now run a 1.8mm steel multi layer drag style head gasket which has brought the compression just under 12:1.

I have spent almost 9 months in Dubai and it's not just hot, it's F**KING HOT!!! So here are a few little things that I see that might be a drama from the time that I have owned my 26/30, the carbs while they would make any RB lover moist in the crutch hearing them at 8000rpm+ probably aren't going to work very well with the humidity and the temperature that is in Dubai even when it get's 'cold' (less hot), you will also need someone that knows how to tune carbs and knows skyline motors well, because if something goes wrong it's going to go wrong in a big way, believe me and it gets expensive after a while.

Not trying to put a downer on anything, all the power to you for making a wicked N/a motor, I just don't think it's going to work very well where you are unfortunately.

Hey Silhouette in which engine you were running these DE pistons?

Finally just got rid of my RB25DET motor and starting this next month. For anyone below is one of the features done on my car


Coming to the thread and I honestly appreciate the inputs from the guys both in favor and against this, its just this project is now a powerplant project.

After checking with people here for the carbs it was advised to leave it for the time being built the engine run it on ITBs (stock 26 or aftermarket) and then do carbs at later stage once engine is all done and running.

Now again two options and need some option and feedback, I am sorry to ask so many questions but not that good in these technicalities

Option 1

Rb26 or RB26/30

Positive points:

Better engine, higher redline and comes with ITBs so less fabrication.

I have mixed feedback, some guys said better just take a 26 engine and just change the piston remove the turbo and run it. Is it doable? got quotes from Nitto and JE they can make custom pistons to increase the compression to 10.5/11. Should I be looking to change anything else in the engine to convert from TT to NA?

Can add a RB30 block better stroke but revving will be lower/

Option 2

Rb25DE head (neo or non neo) with RB 30 Block

Positive points:

Cheaper to set it up (cost 550$ for both engines), compression might be better.

Only thing needed here might be aftermarket ITBs or RB26 ITBs custom fit on this. Only thing saw people going against is that it revs low and 26 head is better then 25

So whats the suggestion guys for both the options? if changing pistons and rods in option 1 can make it run fine then I am more inclined towards it

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Out of luck I went roaming in the scrap yeard to see if by any chance they have some those rare ones RB26DE and found this


Engine came from Japan and was told a fresh import, Seems like series one RB25 head mated to RB30 block very rare to see that done in Japan.

Major upgraded parts I can see were:

Tmoei Cams and Cam gear

Longtube aftermarket headers (huge not sure will fit in S30)

Very neatly done wiring and hooked up on HKS Fcon along with ECU

Greddy intake manifold and a bigger throttlebody

Auto gearbox

Couldn't check anything else but seems like a neat unit there, guy was asking 2500$ for it which is tempting and might come down a bit without intake manifold and gearbox and maybe headers.

Will it be a good idea just to use this and install ITBs/Carbs on it?

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Which way did you end up going?

Have a 240 as well and just found a 26/30 that is built but will likely get torn down to up compression and head mods for more cam lift.

Keeping it NA for the noises but will be using factory ITB  and sorting trumpets....

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