Reliability at 400wrhp(310wrkw)

[Guest Lord]

Well, since i couldnt find a directed anwser in searchs.

I am look for swapping a RB engine into usdm 240sx s14, and there are so many opinion on s14's forums, which dont really help me on the decision. so i decided to ask you guys who owned or at least see a skyline.

I want a engine which will be able to give me 400wrhp(310wrkw) of solid output. i DONT go higher than that.

i also need it to be streetable everyday. i want it to be durable and reliable.

RB20det- 400wrhp will cut its life too much

RB25det- seems to be a good choice...but some say it wont be reliable

RB26det(t)- some say it will be useless if i go only 400wrhp

well....a shop told me that i have to drop one turbo in rb26dett to make it fit in 240sx.. ?!?!

Suggestion ?????

thx

[meggala]

the rb 25 can use rb 26 internals that should make it handel 400 rwkw those to are you only choices the rb 20 would not be suitable

good luck

[Guest RedLineGTR]

good luck man sound like a sweet goal

[Guest Lord]

what part of rb26 internal can be use in rb25 ?

thx for help

if that so, why dont i just use rb26 ?

[Cubes]

Why not look at building up a RB30DET?

Buy the bottom end, rebuild it and buy the nonvct RB25DE (Non turbo) head that bolts straight on.

Then you have a fresh motor. Forged pistons internals etc.. It would be a better option and possibly save you in the long run a rebuild.

[Guest RedLineGTR]

whats in your budget...or how big is it.

[Guest RedLineGTR]

if alot then get a rb26dett and add some parts and you'll get the preformance and reliablility

[Sydneykid]

Hi son of rajab, the problem is you are going just over the limit of pretty much everything in an RB25DET. Injectors, fuel pump, camshafts, pistons, rods, oil pump, water pump, sump capacity, cylinder head flow, inlet manifold, fuel pressure regulator, fuel rail, ECU, intercooler, pipework, internaly wastegated turbo, exhaust manifold etc etc. They all run out of capacity over 450 bhp (280 rwkw = 380 rwhp).

Now you can fix all that if you have the budget. But is 20 bhp really worth an extra $A10K? Because that is the extra it will cost. Our experience has been 450 BHP = $A10K and 500 BHP = $20K. So aiming for 500 bhp is pretty silly because for that same $A20K you can get 650 bhp. The difference is simply a bigger turbo and there is no real cost difference there.

So, my suggestion is to either lower your requirements to 450 bhp and spend $A10K or move on up to 650 bhp and spend $A20K.

Either way, post it and I can give you a comprehensive list of what you need.

Hope that helps

[Guest RedLineGTR]

good info sydneykid.

[Roy]

Im guessing your 240SX is LHD, i would be sticking with a single turbo RB26.

You best talk to some local Montreal workshops and see if any have any experience with the RB family of engines. If there is not much in the way of experience, id be avoiding using RB26 cranks and rods in the RB25 block. Little things like which oil pumps to use, etc could throw a spanner in the works, and add further complication.

As posted above by Sydneykid, that sort of power out of an RB25 is obtainable, but a lot of parts need to be upgraded.

Only my opinion, but if you track down a good condition RB26, ensure the ancillaries like fuel pump, injectors, intercooler, oil cooler are up to scratch. If i understand correctly Turbonetics are pretty big over there, so something like a Turbonetics T88 (or a little smaller) and an internally stock RB26 with an 8000rpm rev limit should do the trick nicely and be reliable.

Some may disagree though.

Some crude calcs in Aussie dollars would be:

RB26DETT- $7500

Turbonetics T88 - $3000

Wastegate and manifold -$2500

IC/Oil Cooler/Injectors/Fuel Pump - $3500

ECU - $2000

R33 Gearbox & Clutch - $3500

Those figure are on the heavy side, but i believe you could comfortably beat those prices if you shopped wisely.

Then you have to get it to fit the LHD engine bay.

Only a thought, i have seen a 1JZ-GTE in a S13 RHD. Id imagine a 2JZ would go into an S14. And id imagine there is a lot more local knowledge with regards to the 2JZ. But then there is the NIssan/Toyota thing.

[Sydneykid]

Hi guys, oil pumps and water pumps are interchangeable. I have had RB25 water and oil pumps on an RB30 block. Last week, I fitted R32 RB26 oil and water pumps to an RB30 block. The only issue I have found is with R33/R34 RB26 which has a larger diameter oil pump drive on the crankshaft. So if you use an R33/R34 RB26 oil pump on the smaller diameter cranks (RB20, RB25 and R32 RB26) then you need an adaptor ring. We use the Jun one.

As I said in the previous post, and Roy's estimates show, you can get 500 bhp but it will cost $A20K including labour.

Hope that clarifies

[Guest Lord]

240sx is a LHD indeed, i have to use only one turbo.

now, between rb25det and rb26det

if i put around $A10k(without labor) on it. which will give me more HP ? both have same lvl of reliability at 450bhp??

guys, i have to admit it, thses are best anwser i ever got since.. i love this board

oh, lets just forget RB26 cranks and rods in the RB25 block.... there are no expert here(can)

[Guest Lord]

reliability and durability. between rb26det and rb25det

???

[hippy]

why not just stick to the rb26 since its been designed to handle the power easily? i don't really see the advantage of using an rb25 when u have to spend that much extra money whereas that extra money could be spend on the 26 and ensure u have that reliability ... or am i over estimating the 26 and underestimating the 25?

[Guest Lord]

u have a good point.

[Guest nismo_trip]

What engine did the American S14 have in it ?

[Guest Lord]

a KA24DE

about 150crank hp and 150crank torque

does quarter in 16s lol

[Steve]

son of rajab, when you say 400rwhp, what type of dyno are you talking? Just noticed that there is a huge difference between the way a Dyno Dynamics (used alot in aust) dyno and a Dynojet (popular in US) Dyno. Always better to compare apples and apples Dyno figures are a strange thing.

In Japan it is common practice to decompress an RB25 - have been told around 8.6:1 is good (HKS 1.6mm gasket) to stretch the RB25 to a reliable 300rwkw. VVT keeps the offboost reasonable, and the engine is alot more boost friendly.

I think one of the big advantages of the RB26 over RB25 is a lower compression ratio, as it is difficult from most accounts to get high boost reliably with 9:1 comp ratio (RB25DET) - thats when you need to start looking at forged pistons etc.

I know what Sydneykid will say about decompressing the engine with gasket:p, but its ALOT cheaper to fit a $300 gasket than fully build a bottom end or buy rb26 internals.

If the engine does blow, just buy an RB30 bottom end and go for it (have to cut holes in your bonnet though:))

[Guest Lord]

i am talking about numbers on Dyno Dynamics.... which gives more conservative whp amount.

i dont think i will be able to get any RB30 stuff in america. first of all, if i swap a rb engine in s14, i will be the first one to do it in my area, maybe entire Canada, which means we dont have experience or knowlege on RB here, so rebuilding an engine or using different type heads or bottom end..will be out of question for me, i wont be able to do any fabric parts or custom fitment.

as i see here, RB26 seems to be better choice than rb25, too bad i can only use one turbo on it. pluz i have to get RB25s R transmission to fit that RB26det. and do custom ic pipes(which i can buy from a company in US*), custom downpiper(*), maybe r33 x-member.......

any here can give me a comprehensive list of setup i need ?

Sydneykid ?

and Roy, the setup you quoted seems to be nice, if i use that Turbonetics T88 turbo, does engines life gonna be cutted?

thx for help

[Roy]

I think most people would agree that an RB26s internals are stronger and better suited to higher hp then the RB25. If you keep boost levels sensible (say 1.2bar) and revs to around 8000rpm, i think the RB26 wil hold together well.

Only prob is higher purchase price of RB26 over RB25. Also you will need to change sump etc to suit RWD.

Also if you were to use the RB25DET the added engine height due to the inlet pipe crossing the rocker cover could introduce height/clearance problems. (could... im not sure)

It always great to be different, but do many local folk put SR20DETs into S14s over there. Would have to be a far simpler conversion, and you could always do a JUN 2.2 stroker etc. With correct turbo sizing you should be able to make your power goal, and will have good internals courtesy of the JUN (or other) internals.

Best of luck with the project, Signal Performance have offices in the US, and i know they have put RB26s into S14 in Japan. Sure RHD but could be a good starting point.