Neo Rb25 Vs R34 Rb26

[zebra]

oil feed for the VCT in the NEO, and head bolts are bigger in diameter for the 26

[Don Dada]

Never seen a high powered 25 neo out of Japland.........just sayin

[joeyjoejoejuniorshabadoo]

Also this might be wrong but I see a lot more blown up rb26s than I do rb25s, could this be due to the higher rpm limit?

this is more to do with the RB26 usually being strapped into a GTR that has 4wd and can generate more sideways g forces than a similarly specked RWD car...

car is running high revs on track, and oil is all up in the head with the sump running low.... 4wd GTR comes out of a corner HARD @ 8000 revs and the slight amount of oil remaining in the sump is thrown to the side and misses the pickup. car gets no oil @ 8000 rpm = bang

RWD car does same thing but doesn't grip as hard an oil does not get thrown as hard and does not miss the pickup, hence RB25 stays alive

So how do the AWD block RB25s neo and non neo differ from the RB26? Many of the Stagea blocks I've seen have interchangeable sump and sump parts with the Rb26.

stag motor is a 25 head on a 26 block/sump setup with all 25 internals....

i just put one into my 33 gtst

[DVS JEZ]

Does the block have rb26 stamped on it Joey?

[Simon-S14]

Never seen a high powered 25 neo out of Japland.........just sayin

and?

theres plenty here in aust.

Mercury motorsports 700 rwhp stock bottom end neo in VC commo for one thing. however unsure how hard it gets driven.

then theres mine... pushing far more power then stock and gets driven hard at as many track days as possible.

[joeyjoejoejuniorshabadoo]

bombtrack's neo has been pushing 300rwkw for 3 years now... although not tracked as yet

[Rolls]

bump for this tid bit

http://www.skylinesaustralia.com/forums/topic/251820-got-over-400kw-atw/page__st__1000__p__5902568#entry5902568

None, all the technology in the RB26 head is present in the Neo head. Valve/port angle etc. The only benefit the 26 head has is more readily available parts

[045HOW]

i have owned 2 R33's, one with S1 engine and the other a S2 engine. when i hit 5500RPM(ish) i get a big kick onwards in torque. i have also driven a NEO RB25DET several times, it feels completely different to drive(obviously because of the constantly variable VCT as opposed to on/off VCT) and has no kick whatsoever. just a much smoother rev range all the way through. can also verify another mate feels the same way about his 34 and notices the difference when he drives his mates sil80 with a 33 RB25DET installed. is this kick coming from vct coming on or off?

also iirc:NEO uses GTR connecting rods to compensate for the smaller combustion chamber.

[Simon-S14]

for the last and final time. the neo has NO constant variable cam timing. its an on/off system the same as r33.

[045HOW]

for the last and final time. the neo has NO constant variable cam timing. its an on/off system the same as r33.

Well. bring the ruckus.

Where's your info and your explanation to my post?

[Hanaldo]

It's been discussed to death. R34 VCT is on/off.

Obviously a 25DET Neo and a 25DET are going to feel different, there are lots of differences between them.

[Simon-S14]

the neo is a smoother engine to drive. you can thank ECU tuning, the intake runner differences and the turbo differences for that.

[045HOW]

the neo is a smoother engine to drive. you can thank ECU tuning, the intake runner differences and the turbo differences for that.

fair enough. do not like. i prefer driving a 33 over a 34.

[JonnoHR31]

i have owned 2 R33's, one with S1 engine and the other a S2 engine. when i hit 5500RPM(ish) i get a big kick onwards in torque. i have also driven a NEO RB25DET several times, it feels completely different to drive(obviously because of the constantly variable VCT as opposed to on/off VCT) and has no kick whatsoever. just a much smoother rev range all the way through. can also verify another mate feels the same way about his 34 and notices the difference when he drives his mates sil80 with a 33 RB25DET installed. is this kick coming from vct coming on or off?

also iirc:NEO uses GTR connecting rods to compensate for the smaller combustion chamber.

the kick at 5500 is just the standard map in the ecu, at any airflow higher than stock its rich and retarded everywhere on boost but especially around the midrange, sometimes the changes in individual cells are so big its like flicking a switch as you described.

vct is on/off as said. neo just has it activated over a slightly different rev range from memory.

neo does use gtr rods but its nothing to do with the chamber size, they're the same length as 33 rb25 rods. the smaller chamber is allowed for in the pistons.

Edited July 9, 2011 by JonnoHR31

[Rolls]

Interesting, I thought the rod change was due to the combustion chamber change and the pistons were the same, happy to be proven wrong though.

[Adriano]

Does the block have rb26 stamped on it Joey?

No, rb25

[discopotato03]

I wish someone would prove conclusively that Neo chambers were smaller because I've never seen anything to show it .

I know that on some later/last versions of some engines manufacturers went to long reach spark plugs so they could improve cooling galleries around the chambers , do Neos use different style plugs to R33 RB25DETs ?

Anyway I gather Neos use the same sized valves and if pistons are same/similar the static CR must rise if the chamber volumes are less .

What truly gives ?

A .

[Simon-S14]

im pretty sure neo's use same plugs. i use BCPR6ES's in mine anyway.

im with you.. not all that convinced that the chamber is smaller... maybe a slightly different size

[666DAN]

im pretty sure neo's use same plugs. i use BCPR6ES's in mine anyway.

im with you.. not all that convinced that the chamber is smaller... maybe a slightly different size

As far as I knew it was only the lean-burn RB20's that were marginally smaller (also a redesigned shape)

[wolverine]

I wish someone would prove conclusively that Neo chambers were smaller because I've never seen anything to show it .

I know that on some later/last versions of some engines manufacturers went to long reach spark plugs so they could improve cooling galleries around the chambers , do Neos use different style plugs to R33 RB25DETs ?

Anyway I gather Neos use the same sized valves and if pistons are same/similar the static CR must rise if the chamber volumes are less .

What truly gives ?

A .

The pistons are different so this should account for the same static comp but different chamber volumes.