rb20 vs rb25

[demonic s12]

ive been looking at the rb20 as a possible swap for my s12, i was wondering if the rb25 is the same as far as dimensions go, like will it fit in our engine bay?
im in the beginning process of looking at these at possible swaps, im aware of the advantages and disadvantages, the main thing is i want a totally unique car that can do everything reliably and well, my goal is in the 350 range to the wheels with great handling to match, anyways let me know youre thoughts

[nismo200sx16]

rb = $$$$$$. if you are only looking for 350 go sr20det,ca18det.or a ka24det. a turbo ka in a s12 would be unique. I would say just having a nice s12 would be unique. the rb will fit. I think the rb 20 25 and 26 all have the same size block. the rb will not handle very well. lots of under steer.

[demonic s12]

isnt there a way to correct the understeer via swaybars etc? the rb is cheaper than the sr20 which was my first choice, front clips sre available starting at 1100 bucks, i just want something special, thats why i bought this car, ive maybe seen 3 s12s in my area and they look like crap, so i think  my car deserves to be untouchable...
ive thought ka...but wouldnt that be as heavy as the rb? and would it really have the internals to make 350 rwhp reliably?
im also (realistically) looking at the ca18det, but again... can it make that power?
the sr20, id like to have above either of the others, except the prices are becoming prohibative!
unless you all know something i dont?

[Cavi Mike]

I still don\'t see the point of using a RB20 over a SR20. They\'re both 2 litres. The only reason would be for the \"I\'m cooler than you\" factor. In another words, the 2Ghey2Delerious factor.

[Simon]

I dont see how fitting an RB25DET would be any harder than an RB20DET.

Go the RB25, engine is a little bit taller, but shouldn\'t be a problem in an S12, plenty of bonnet space (I crammed an RB25 in my S13)

RB25 will produce huge power with little mods, and produce it happily all day.

If you want reliable power, you cant go past an RB.

For some reason a lot of people dont like the idea of putting RBs into s12s or s13s.  They carry on that it\'s too heavy and the car will handle poorly.  The car will not necessarily handle any worse, just differently than it used to before it stacked on the pounds.

You have two realistic options to get big power:
1.  Build up an SR, but remember, it\'s still just a 2.0L 4cyl, you will really be ringing it\'s neck to get the same power you could get from an RB25.
2.  Build up an RB it will handle the power much better. Downside is you will have to deal with the extra weight (bigger breaks, better suspension)

just a note, most people who dis RBs own SRs themselves, have a look around on nissansilvia.com for threads where people are installing RBs.  Even threads where the poster clearly states they dont want their thread hi-jacked by SR extremists..... in they come, flaming wands in hand ready do dish out a serve to anyone who dare opose the all mighty SR.

I\'m not saying either engine is necessarily better than the other.  They both have pros and cons.

Just make up your own mind based on the facts.

*end rant*

[nismo200sx16]

if you can get an rb clip for 1100 go for it. thats cheep. my sr clip was 2800 shipped. I am one of those SR extremists with the flaming wands in hand ready do dish out a serve to anyone who dare opose the all mighty SR. but I would like to see different swaps in the s12. its not all about whats best its about whats best for you.

[Simon]

if you can get an rb clip for 1100 go for it. thats cheep. my sr clip was 2800 shipped. I am one of those SR extremists with the flaming wands in hand ready do dish out a serve to anyone who dare opose the all mighty SR. but I would like to see different swaps in the s12. its not all about whats best its about whats best for you.

HAHA   :lynch:

[iB6uB9]

the 25 is a taller motor at the rear due to inlet manifold, but this can vary depending on model ie neo or r33.
i would go rb any day of the week becasue sr\'s are fragile and dont like to be reved, you can bounce an rb off rev limit effortlessly, without too much worry.

if you decide on using a 25 you would be best off using the steel brakets and mounts off an r32 because it will make mounting the engine much easier

[Simon]

R33 mounts bolt up the same as R32 but the engine will sit a little lower.

I have R33 mounts in my S13 and still have clearance issues.  It\'s not fun when your speedo cable gets jammed on the bonnet at full throttle ;-)

[Jsvob03]

...HEY, back off the turbo KA in an s12...thats my project...(still in research/planning stages)...

[demonic s12]

im just kicking the idea around, of course i have to look at the ups and downs... of each engine and weigh what the best choice is, also, i think itd be cool to make a huge bbq out of a skyline front end for my backyard. :banger:

[Joel07]

LOL, I wouldn\'t expect much out of a clip for $1100.  Beware when buying JDM parts, often times you get what you pay for.

[sak1782]

bringing a thread back from the depths of old threadness...


what is the size difference from the rb25det and the rb26dett? the obvious is the twins hanging off the drivers side, but could this work...

please, please, dont reply with "anything is possible with enough money"

Im new to the nissan world, but not to cars or engine swaps. Im expecting to spend around 12k to get this all done.
Thanks guys,
Scott

[sak1782]

i just browsed through some older threads, and found some people talking about it...but no pics or real words on what is all needed.

What are some other good nissan sites that I could look around for guys who have done the 26 swap in a 240sx?
Is there an RB20/25/26 forum out there?

Thanks in advance guys.

[ryan206]

You need to talk to Colin (Draconis) about this.. He has an RB20DET in his S12 and could probably give some good advice on it.

I'd go RB over SR.. Why? RBs are cheaper, and they can handle the power better. SRs are good engines, I'm not saying they're bad, but why pay more for an engine that has 2 cylinders less?

The main thing the SR has over the RB is the fact there is more aftermarket support.

Personally, I'm going CA18DET or KA. I want a CA18DET cause they are a drop in engine, very little work required, but I love the way RBs sound and preform.

An RB20DET half cut goes for $2000 and an RB25DET goes for $3200 at UP Garage. KAs go for around $200-$500 and CA18DETS go for $1900

[Draconis]

Ok, here's some of my info.

RB20 usually cost less than a SR20, but as of late, prices have gone up due to an increased demand for them.  There is actually more aftermarket for the RB than the SR, it's just being able to access it.  RBs are much more tunable and you yield a lot of gains just by playing with the timing.  SRs are more fagile than RBs.

Thing is, if you are looking for a good budget swap and really only want 300-350hp, then I would go CA18DET or KA24DE-T.  Much easier to do, more access to parts and just about every part of a CA18DET has a domestic equivalent from other Nissan engines that did come Stateside.

And Cavi Mike, I just want to say that your comment is ignorant.  I thought about all my options when I did my engine transplant and came up with solid data from multiple points that led me to the RB20.  First of all, just ask the Australians.  I think Ib6ub9 is also Australian for I have approached him and others for information.  And he is right.  The Australians got their shit straight and from the many I've talked to, the vast majority will point to the RB20 for several reason and one of which is being reliable.  They are far ahead of us Yanks in terms of Tuning/drifting/Japanese imports.  I've also talked to a couple Formula D drivers and techs and though they are split due to their own preferences and such, it only goes to show that the RB20 is a great alternative.

[RB25sx - SLPR]

Ok, here's some of my info.

RB20 usually cost less than a SR20, but as of late, prices have gone up due to an increased demand for them.  There is actually more aftermarket for the RB than the SR, it's just being able to access it.  RBs are much more tunable and you yield a lot of gains just by playing with the timing.  SRs are more fagile than RBs.

Thing is, if you are looking for a good budget swap and really only want 300-350hp, then I would go CA18DET or KA24DE-T.  Much easier to do, more access to parts and just about every part of a CA18DET has a domestic equivalent from other Nissan engines that did come Stateside.

And Cavi Mike, I just want to say that your comment is ignorant.  I thought about all my options when I did my engine transplant and came up with solid data from multiple points that led me to the RB20.  First of all, just ask the Australians.  I think Ib6ub9 is also Australian for I have approached him and others for information.  And he is right.  The Australians got their shit straight and from the many I've talked to, the vast majority will point to the RB20 for several reason and one of which is being reliable.  They are far ahead of us Yanks in terms of Tuning/drifting/Japanese imports.  I've also talked to a couple Formula D drivers and techs and though they are split due to their own preferences and such, it only goes to show that the RB20 is a great alternative.

Amen my RB brother.

To all those who quote that the RB will make the car understeer etc, im sorry, but that is a crock of shit. I find it funny that people mistake forum jibbery-joo for reality and fact.

IN the s12 chassis, the primary reason to go with an RB20 is the transmission.. If you look at my thread in the hybrid section you will note that the entire transmission tunnel had to be cut out in order to make room. IN ADDITION, the driveshaft yoke is uncommon and needs to be special ordered from somewhere like thedriveshaftshop.com. The RB25 has a much stronger transmission, but at the cost of fitment, and expense. NOT ONLY THIS, but I have been having cooling problems since day 1 as I can only use that car above 60km/h or else it pukes it's coolant.

Also, if you look at aftermarket 'plugin' EFI systems, its pretty much either RB20 or RB26.. Even BIKIROM only works with an RB20 ecu.

You will be faced with the fact that you have less than an inch between your crank pulley and your radiator, and need to be ok with that..

For your power goals, it is simply not advisable to get an RB25.

Draconis and I can give you pointers in terms or wiring, but he would be best as mine is simply a hack job and I am going standalone shortly..

Just go KA, get it running, then turbo it, and be content.

-Dan

[Draconis]

I agree with the understeering issue.  That is a bunch of bull.  Actually, I weighed my car with the RB vs the VG and there is very little difference when looking at the car as a whole.  If anything, it makes the nose a little bit heavier, but for all those who want to drive their car, it's better since you can swing your rear out while having your front a little more cemented in place.

As for going Stand Alone, nice!  I havent gotten the chance to go there.  I got away cheap with buying a Emanage Ult at a really cheap price off a guy who ditched his RB20.  Saved me about $400 as compared to me going Emanage at all.

The amount of power you can get out of a RB20 is perfect for how much extra weight you have in the car.  It is easily upgradeable and can reach with at least 332rwhp (proven in AUS) with stock internals, just upgrade turbo/injectors/bov/wastegate and the controllers to go with.  And up to 4-500 if not more with some actual work done to it.  And even then, it is still cheaper than going SR considering all the costs.

[Arro]

THANK GOD Dan and Colin finally spoke up... this thread was useless without the input from people who actually run RB's in their S12's. And I think they established that it's fine... and in fact, a far better choice than an SR for a number of reasons.

To get it 100% back on topic, the original question was RB20 vs. RB25, and it seems like now the only real consideration is price and availability, so the choice is up to the OP of this thread.

[falkhen]

well...
another note thats needs to be covered is the Power Steering lines in the RB as factory the engine comes with Oil cooler to fix this.
your stock lines will work but over time about 3months they will sweat and final rupture.
I have covered this in a howto power steering mod.
cost like just under $80 to fix the highpressure side.


the best feature about RB is the amount of cylinders.
even if the SR was like that( wow thats a CA20DET )
its possible to make the power but how long will it take.( time is refered to RPMS)
More cylinders is better in making power when it comes to Pistons driven engines, though mass is its draw back.


steering issues are resolved with Suspension proper fitment of the right sized tires... 215's are not wide enough....lol
225's and larger.

Sway bar in the front wont fit with out modifieing the oil pan or custom sway bar.


Im running Stock suspension(non lowered) car handles fine.
ask Colin, redkneck. and those who have riden in the car.
though its a bit loose err boatish..