RB25 Neo Block Compatibility

[throckmorton]

Hi all,

To preface, I have searched tirelessly, to no avail.

As far as I can tell, RB25 S1, S2 and NEO blocks are identical. The Neo heads are obviously very different. I have an S2 25 head and have found a good deal on a NEO block. I can't seem to find a definitive answer as to whether I can use the Neo block with the S2 head. I'm going fully forged and am looking for confirmation that the Neo block and crank will accept forged non-Neo 8.5:1 pistons and rods and not run into problems with the S2 head. As far as I can tell, this should have the same outcome as an S2 block with the same rods and pistons.

Preemptively, buying a Neo head is a last resort due to my location and freight costs.

Cheers

[ChrisW434]

I'm building a forged Neo myself right now, and the different pistons allow for the different cylinder heads, and the relevant compression ratios. Got to run the correct piston to suit the head, if you want the package and known compression ratio to be simple, and easy to tune etc. Blocks should be same.

Do some research on oil gallery restrictors (in the deck of the block) as well, as their configuration depends on the head you're running as well (VCT or non-VCT). Platinum Racing Products has a good diagram on their Insta page explaining this...

I'm not a guru yet, so confirm what i've suggested elsewhere as well. But as far as i can tell, get those couple things right, and you should be sweet.

 

 

[Rusty Nuts]

6 hours ago, throckmorton said:

To preface, I have searched tirelessly, to no avail.

 

You did not try very hard at all, over the years this has been discussed many times

If you search Neo block you find many pages, I guess reading through the titles was  too time consuming

Edited August 25, 2020 by Rusty Nuts

[GTSBoy]

VCT oil drain differs between them. You will need to do something about that. But the blocks are otherwise able to swallow pistons from either with do problems.

Neo rods are RB26 rods and therefore better than vanilla 25 rods.