converting rb25 series 1 to Neo?

[meet07]

I wondering if I could take a Neo rb25 and use all my series 1 stuff. I mean I have series 1 harness, intake plenum,turbo header,rail and a AEM as well.I know the CAS's are diffrent as well as the cam key, but unsure about everything else.

[Carl H]

unless you replace the pistons with decomp pistons you'll end up with mid 11:1 compression using a neo head on a r33 bottom end.

if you want to run a neo off of an aem then just make a jumper harness and run it off of the neo harness...else there are a lot of plugs to splice.

[meet07]

I dont want to use the neo head on the rb25 series 1 block. I currently have a series 1 that has all the supporting mods......aftermarket intake,injectors, AEM for the series 1, stec manifold, s366 turbo,dp, injectors and all. I've messed the motor up a few times. I was kinda trying to weigh my options. I was considering starting from scracth with a stock rb25. The Neo's are going pretty cheap now days and if it only takes a few parts or a few wiring changes to make the neo work then I might consider it...

[ncturbospecv]

Ive actually been looking into this myself. Using a neo longblock(bottom end and head) with all the s1 accessories. As far as i've gathered from a few threads it is possible to use the s1 electronics as long as you swap a few things but there are a few issues.

1. CAS. from what i've read you simply repin the cas plug to use the neo cas. from 1234 to 4321
2. Coils. the coils not only have the ignitor built in but mount differently in the head. you can either make mounts for your s1 coils and use the igniter or wire in the neo coilpack harness by eliminating the igniter.
3. injectors. Can be fixed if you just use your greddy style manifold with the injectrors you are currently using.

then there's the differences in neo blocks between the r34 and stagea. stagea's awd blocks need the oil pan baffles trimmed a bit because the pickup is a little further forward than the rwd block but the rwd oil pan should bolt up otherwise.

I think thats it but i might be forgetting something. If anyone else has definite answers or if anything i posted is wrong please let me know as i am looking into this as well.

[meet07]

No see I already have the series 1 oil pan. As far as the oil pick up.....I wonder if the series 1 pick up will bolt right up? I'm using the LSx truck coil packs. Pretty much The ignitor is built into each coil pack so I should be good there. As far as repining the CAS that sounds like cake. So from what your telling me I should be able to convert from my series one short block to a NEO short block with little headache!!

I guess the only other question is will the AEM CAS disk pit into the NEO/series 2 CAS??

Guess I may need to do a little more digging...

[ncturbospecv]

Problem with the oil pickup on the AWD blocks is that the pickup is actually placed forward on the block itself. In the pick below you can see there's a flat spot on the block behind the existing pickup where the normal rb25 pickup would be. This is only on the AWD blocks. If you get a normal r34 rwd neo then its just like a normal block with no issues.

The only other info i couldnt find a definite answer on was the fact that some of the stagea neo's might not have oil squirters or the rb26 rods. So the safest and more simple route would be to make sure you get an r34 rwd motorset.

[ncturbospecv]

So basically if you get a rwd r34 neo motor its basically just dealing with the coil packs and changing the CAS pinout.

If you get a stagea awd motor then you have to deal with the oil pan issue as well.

[Orthank]

Anything not internal to the head should bolt up fine except the coils like was said. ECU is all different but from the mods you listed above all you have should fit.

My RB25DET NEO in my r34 is at the tuner right now, and I have had a hell of a time with parts during the build because virtually everything is unique (in weird ways) on the engine and more of a headache to work around. That being said it is a much better engine that the R33 s1 and s2 RB25DET. Many GT-R internal goodies were added to the NEO to make it run better and with more power. One more note not using an ECU solution designed for the NEO will hurt the performance because some functions of the engine will not work right or in some cases at all.. The only ones that I am aware of are The Power FC, HKS FCON VPRO & IS and the NISTUNE mods. If you know of any others let me know. But that is one of the other s*** things about the NEO.

[Miguelone]

The coils themselves mount up in a slightly different pattern but apart from that they are exactly the same as S2 coils, When I first bought my car it actually had Neo coilpacks in it(Only held in by 1 bolt each). But they do work fine. All you'd really need to do to make them fit properly would be to swap over your coilpack brackets with your S1 33 ones. Other option is of course to keep your S1 coils, they're no better or worse they just have a separate igniter.