Rb25det Head Query

[MC-WOSHY]

Hey guys,

I have a S1 R33 with a S1 RB25DET. Recently I did a compression test on it and it says low on compression. So I bought another 25 head which I plan to swap over.

However upon taking it to a Head Shop today, they have stated the head may be a NEO 25. On the exhaust side of this head it says 5L83 and I'm just wondering if anyone can confirm this is indeed a NEO?

Also, is this going to now not be compatible with my S1 RB25 block? Just because this new head is straight and in good condition.

Cheers for any help!

[Ben C34]

Put up some pics.

If it is a neo head your compression will be too high.

[MC-WOSHY]

This is the only photo I have unfortunately as the head is at the head shop now -_- probably not gonna help

[MC-WOSHY]

[Ben C34]

This is the only photo I have unfortunately as the head is at the head shop now -_- probably not gonna help

You are correct. ...

[MC-WOSHY]

I think I may need to ring Nissan and give them the code, they should be able to tell me

[AngryRB]

a neo head uses a different cas, black cover on it, I'm after a neo and selling a S2 head with tomei cams , might be interested in a deal here

Edited April 25, 2015 by AngryRB

[MC-WOSHY]

Oh ok, I just got the bare head as you see in the picture, didn't need the other stuff so I think I'm unable to tell

[Ben C34]

Once you can get a pic of the timing gears from the front, or even the same shot you posted with nothing wrapping the head.

Can tell easily from.that.

[AngryRB]

wouldn't it be easy to tell if its solid lifters or not ben?? they have smaller runners too don't they, wonder what the difference is there....

Edited April 25, 2015 by AngryRB

[MC-WOSHY]

Ok mate, will get that tomorrow!

[Ben C34]

wouldn't it be easy to tell if its solid lifters or not ben?? they have smaller runners too don't they, wonder what the difference is there....

The runner size difference is minimal, unless its the na head, which is noticeably smaller.

The lifters are pretty obvious but the vct allen head grub screw rather than bolts and lack of vct oil drain on the side of the head is obvious from a distance.

[iruvyouskyrine]

That pic you posted is a neo head.

[sonicz]

Yup Doctor Neo Cortex has a pretty big head.

[xntrq]

Yes it is a NEO head. The coilpack bolts straight onto the head in the NEO as with the non NEO engines are mounted on a bracket which are then bolted on by 12mm bolts.

[MC-WOSHY]

Ok, cheers for that info guys!

Next question is, is it going to fit on my S1 RB25 block? Without any issues? As I know the NEO has VCT etc

[scotty nm35]

No, the compression will be way too high as has already been said above. Swap with Angry RB?

[MC-WOSHY]

Ah ok! That's fair enough and swapping might be the go!

But I'm in WA and idk where he is

[iruvyouskyrine]

Yes it is a NEO head. The coilpack bolts straight onto the head in the NEO as with the non NEO engines are mounted on a bracket which are then bolted on by 12mm bolts.

Correct. This is how I was able to tell.

[MC-WOSHY]

So I have some more photos,

These help at all!? Just to be super duper positive it is in fact a NEO before I decide to sell it off or swap it

Edited April 28, 2015 by MC-WOSHY