Rb25+ Bolt-Ons And Manual Box, Or Rb26 Swap?

[floody]

After some experience here, looking at ploughing some time and money into our S1 Dayz this year.

Two dominant options are:

-Keep RB25, do some bolt ons (i.e. turbo, intercooler, exhaust, injectors, ecu), manual swap, bigger brakes.

-Buy RB26 front cut or smashed R33 GT-R, swap in engine, box, brakes, freshen up (i.e. pumps, gaskets etc), dumps and exhaust, but otherwise keep mostly stock.

What's going to be better bang for buck for similar dollars, mild bolt on RB25 or near-stock R33 RB26?

Goes without saying would do coilovers etc at same time.

Of course there is 'just buy a 260RS' but I am more keen to stick with the devil I know.

[KiwiRS4T]

It really depends on your goals but mostly doing up the RB25 will be easier and cheaper.

Just to take the RB26 first - a fellow Aucklander bought a GTR half cut for his Skyline and ended up having to put a new crankshaft in it. Even without that an RB26 half cut is not that cheap and you will need to pay for other bits and pieces as well as some labour (depending on how much you do yourself). And how many GTRs are just driven to church on Sundays by an old lady?

An unopened RB25 in good nick with a good tune can run at up to 300awkw for years if treated right.

260 - 280kw is really quite fast and easily acheivable with either a GT3076 or a Hyperdrive turbo, good front mount, Z32 afm, 3in turbo back exhaust and better injectors. A new fuel pump would be wise but stock bov, fpr, manifolds should be fine. For ecu a Link would be ideal but a Z32 ecu with a Nistune chip would do fine (with a manual box).

A set of GTT brakes with decent pads and brakefluid won't set you back too much.

[coparts41]

remember a 33gtr only puts out the same as a 25 neo ,still got to modify it to get any gain,may as well do the 25 that you have.

[4bidn1]

remember a 33gtr only puts out the same as a 25 neo ,still got to modify it to get any gain,may as well do the 25 that you have.

Exactly right ! This is what i considered when doing my replacement in my s1 ended up putting a neo engine with a gtr gear box behind it usual mods 3076r snail nistune cams blah blah should be finished within the next few weeks just got to find time to work on it lol. Same turbo with 550cc injectors on only 15psi on my stock s1engine made 244rwkw through an auto never got to yurn boost up .+1 for rb25

[Duncan]

the rb26 will have a lot more potential for power in the future if you think that might be a factor.

But either will be good fun....I went the rb30+manual route on mine and it is brilliant

[4bidn1]

the rb26 will have a lot more potential for power in the future if you think that might be a factor.

But either will be good fun....I went the rb30+manual route on mine and it is brilliant

just wondering on what basis would the rb 26 have more potential for power? rods and heads are basically the same rb26 to neo, so your looking at 100cc more displacment and every other factor is a variable bolt on ie plenum turbo/turbos injectors just interested.

cheers jase

[KiwiRS4T]

RB26 comes with better head - would have liked one for my RB30 but no budget for that! Also the 26 intake plenum points straighter so doesn't impinge on the battery space as much as the Greddy type.

As Duncan says I can highly recommend the RB30 route - so much low down torque - but its a bit of a major compared to a few bolt ons.

[4bidn1]

hmmm rb26heads and neo head castings are virtually identical rb26 heads have slightly better hardware ie cams springs ect but if your after signifigantly more power from ether you would be changing these any way, as you would the plenum on the 25,(only a real advantage at over 350ish kw) where as the 26 plenum would do you. so would the extra original out lay of the 26 be worth it when that money could be spent on mods for 25.

but def a 25/30 would be the best

[Duncan]

yeah I'm sure it is possible to get similar or even better results out of an rb25 neo head, but I mean for 95% of people. rb26 bolt ons are easy and cheap and plentiful for anywhere from 250-400kw. getting the same power out of an rb25 will cost more, but is certainly not impossible.

If we're talking about building a full house motor, go for it, the sky's the limit! But I guess that's not really OP's question.

[jet_r31]

a rb26 over a rb25 neo in a stageas conversion is a pretty pointless conversion(in my eyes) the Rb26 will cost lots more to modify, let alone the fact that

the Rb26 is more likely to spin a set of bearings and need a rebuild,( and this is the biggy for me) your way more likely to get a good condition neo that will last much longer.

people are saying there f**kloads of Rb26 s/h perfromance parts around, well theres f**kloads of s/h Rb25 performance parts on this site aswell...i woudn't pick a motor for that.

Over 400rwkw i can see the pont in a 26..but its still in a stagea, your talking huge money, broken gearboxes would be just the start.. If you talking full rebuild i's rather have a 30 bottom end on a 25 top , auto,

built for torque

and wide rev range, rather than a peaky 26, to shift

the fat lard arses C34 weight.....if you want a fast car..buy something else thats lighter..or win lotto, as these things need massive power to go half decent compared to most cars.

How much power does the Op want?, i bet its not 350-400awkw?

cheers

darren

Edited March 10, 2012 by jet_r31

[Dream15]

Why not spend 5k and make 300kw out of an rb25 neo than spend almost all that just for an rb26 which will be making stock power. And when are you going to use 400kw in a stagea? Certainly not on a stagea cruise seeing as most are making not alot of power and spend more money on light globes than performance parts.

[wolverine]

RB25/30 if you are pulling a motor out.

[4bidn1]

RB25/30 if you are pulling a motor out.

Im pritty sure he was looking at a cheeper way not spending all his money on sump adapters and converting the head to fit a 30 bottom end and running top mount manifold to run a decent turbs on coz the 30 block sits a lot straighter. hell if we are doing all this lets go a 3.3l stroker bottom end lol the truth is power performance vs $ the neo engine and bolt ons come up trumps how much power does he want to make

[wolverine]

I am pretty sure he said existing RB25 with bolt-ons OR an RB26 which will require the engine to come out. 'Cheap' and 'RB26' are two words that rarely go together in a sentence.

IF the engine is coming out then why frig around with an RB26 (or neo RB25) which does nothing to address the lardy nature of the Stagea. More torque down low as Duncan can attest is a winner.

Personally, I would go the bolt on option with the existing engine as it is the cheapest way to go.

ps. the RB30 can still use low mount turbos.

[floody]

Ok to clarify. I have an S1, so its not a NEO, but I think thats academic. Either way it will get a manual box, and will have coilovers, bigger brakes. So purely talking about the engine and attached bits.

My thinking is with the same budget I can either add a lot of high end bolt ons to the RB25, i.e. turbo, injectors, front facing plenum, ecu etc and do a manual swap, or pick up a bargain RB26 halfcut/parts car, give it a quick freshen and install it pretty much stock standard.

So, basically, choice is between mild bolt on RB25 (low mount turbo, good ecu, injectors, plenum, exhaust, maybe cams) or fresh, near stock RB26 (maybe with N1s or similar, probably Power FC).

End of the day want something responsive and fuss free, for day to day use - this is why I like the RB26 mostly OEM route - but I gather I should be able to see the same results from the RB25 then with a good turbo and choice of tuner. It just strikes me I may be able to sink more into good supporting mods with the RB25 compared to RB26. Mid 200s to 300kw would be plenty.

Am I on the right track?

Edited March 12, 2012 by floody

[4bidn1]

The 25 is the way to go no need for plenum just run fmic,piggy back ecu greedy ulitimate or link , larger injectors i used 550cc high flows, z32 airflow meter coil packs i used yellow jackets a garrett 3076 or a hypergear highflow 14psi actuator, intank pull pump i use a walbro, surge tank and external 044 this combo on a s1 made 244kw on 15 psi through an auto so for a manual you woulf expect 260ish then chuck some pon cams in turn up the boost you should see 280ish maybe more (still have my injectors for sale) lol

[4bidn1]

Also just finished my manual conversion last week end so if ya got any qs about that pm me. do all my own work on my cars past and present so any help i can be fire away

cheers

jase

[rb30dett]

keep the 25 shift kit the auto add bolt ons then when time to rebuild go the 30/25 I love the rb30 behind a good auto rb25/30 + t67-25g, 3k stalled auto FTW?

Edited March 12, 2012 by rb30dett

[wolverine]

The 25 is the way to go no need for plenum just run fmic,piggy back ecu greedy ulitimate or link , larger injectors i used 550cc high flows, z32 airflow meter coil packs i used yellow jackets a garrett 3076 or a hypergear highflow 14psi actuator, intank pull pump i use a walbro, surge tank and external 044 this combo on a s1 made 244kw on 15 psi through an auto so for a manual you woulf expect 260ish then chuck some pon cams in turn up the boost you should see 280ish maybe more (still have my injectors for sale) lol

[4bidn1]

keep the 25 shift kit the auto add bolt ons then when time to rebuild go the 30/25 I love the rb30 behind a good auto rb25/30 + t67-25g, 3k stalled auto FTW?

yeah my car was awsome to drive with the shift kitted auto would have been perfect with a highstall and the 3076r on it . looking back would have kept the auto but had gtr box sitting there . s1 shift kitted auto still up for grabs to