Rb25det.....Worth it?

[woods1]

In recent months I've been starting to get itchy feet with my s14a. I've had it 2 years, stage 1a, good spec and its a really nice car but something is lacking and really fancy a change but don't think i could let the car go if I was to sell it.

Really yearning for some 6 cylinder noise, so thinking as I hate driving it over the salty winter months, take it off the road, get a crap daily, sell my mint sr20det and put some towards getting a r33 gtst running car and swap it over?

Am I wasting my time with doing a swap as I'm correct in saying a rb25det with breathing mods + map would be about 350bhp which would be similar to stage 3a?

Fairly straight forward swap I assume using a r33 cross member + custom short prop and modified gearbox mount?

It's either this or I get a r32 gtst but can't really bring myself to sell it as tbh I'd want more for it than its probs worth? Any info or people have done this swap with input would be great. I know it's common with the s13's but not too much on s14's.

[green_rs13]

seems like a bucket load o work to wind up with 350 a 2871r and some 740's will see you over that number

[boss]

i built RBS14a and i love it,

the engine is fairly stock, got pump, plugs, full 3" system, apexi intake, FMIC, run about 0.8bar, RB25det gearbox, and got a 4.1 diff,

and i LOVE it, so much more torque compared to an SR, very drivable ( if thats even a word )

the noise is amazing, and due to it being fairly stock, im gonna guess at circa 280bhp, its very responsive,

budget wise, think of what you're going to spend, and double it,

if you've got a donor car, then the swap will be a little more straight forward,

R33 cross member is definately the way to go compared to $$$ conversion mounts,

use a 180sx rad,

you'll need your prop modified, use the r33 g/box nose on the s body shaft,

move your rad forward into the slam pannel around 1" and use an SR20 viscous fan,

use an s13 power steering pump ( the union is correct for the s body power steering line, and the alignment is correct for the RB front pulley )

download john bennets wiring diagram,

there are LOADS of threads about this on the sxoc, and plenty of people doing/done it, i'm sure there was an RB register at some point....?

[woods1]

Yea there was a register but never actually gave details on builds, reviews and such.

How much did it cost you to build yours?

[boss]

it was about 2 years ago, so prices may have varied slightly,

engine, gearbox, cross member, harness, ecu, afm - 1500 delivered

prop - cost me £50, and a further £50 to have modified, propshaft clinic, which i believe dunning and fairbank took over,

rad - 100

loom, made myself, but there are people out there willing to carry out the conversion,

i already had the car, and there will be loads of things ive missed out, but its all the little bits that add up i guess, hoses, clips,

initially i made my own forward facing plenum by modifying the stock one, then i bought a freddy ( greddy copy )

i upgraded to vibratechnics engine and gear box mounts,

R33 front pipe,

you will want to fit an oil cooler, RB's seem to run hot, good excuse to fit an oil filter relocation as well, also, relocating the battery to the boot make things easier,

chucked a genuine cambelt on it whilst it was on the bench,

just reading back what i've written, it doesnt seem alot, it felt like i spent alot and gather alot more parts at the time....

i might have put a build thread up somewhere on here, i'll have a look

[woods1]

How hard was the wiring? Do all the gauges on the standard clocks still work okay?

What the shifter location like too? Does the box sit any further forward/backward?

For some reason I keep thinking the prop will be hard to sort but is it just a case of measuring how long it needs to be and give the prop place both ends to weld and balance?

[royellison]

Mate il show you my rb25 s13 if it helps, iv ran mine for a long time and did it all myself.

Only in ormskirk so not far from you. I pop down to much hoole a fair bit aswell.

[piman2k]

Can understand your love for the noise, I love it too I would consider one myself but IIRC the RB25DET is a big old heavy engine. Then again, if the torque is as staggering as people say then it could be very good fun. You're probably best having a drive in one.

[igralec]

I'm getting 0.5 bar at around 2k RPM in 4th, it's got a lot of torque (4th gear 1800rpm, you floor it and it pulls like a train), you don't really need more than 1500rpm for normal driving, if you're running the s14 manual diff 5th is a bit long though My ex stage 3a SR20 was plain dead below 2000rpm compared to this.
Stage 1 is ECU, exhaust, filter, 0.85 bar, grade 6 plugs, FMIC, that makes around 320hp give or take, i think stage 2 is a reworked stock turbo with steel turbine wheels that can take around 1.4 bar, Z32 AFM, 555cc injectors (or maybe 444), that should make around 400hp, maybe a bit more.
But the trick is it has torque low down so pulls nicely and smoothly (no kick, not even like a standard SR20, nowhere near the s13 kick), but overall it doesn't have a lot of torque as it's very limited with boost because the stock turbo can maybe run 0.9 bar if it doesn't blow up. I'd imagine it really comes alive with a decent turbo

[royellison]

Iv just baught a gt35 for mine, but at the minute it's running 0.8bar boost, fmic, apexi filter, 255lph fuel pump. Goes well just with light mods.
Te whole thing about it being unbalanced with a heavy engine is crap I think, I drive mine daily and don't notice te difference.

[zeppelin101]

I drive mine daily and don't notice te difference.

I can imagine you wouldn't, but you would notice for circuit driving. Not drift, I hasten to add.

[woods1]

Mate il show you my rb25 s13 if it helps, iv ran mine for a long time and did it all myself.

Only in ormskirk so not far from you. I pop down to much hoole a fair bit aswell.

Yes!!! il pm you mate

[woods1]

just trying to weigh up the costs against engine power, heard the stock turbo is weak but didnt think it was that bad

Part of me would just love the project over winter and the challenge, but im also scared id remove a mint sr20det for a "low milage" (like every engine advert says) rb25det that actually is in a bad state/high mileage and would go bang lol

[royellison]

Iv just baught a gt35 for mine, but at the minute it's running 0.8bar boost, fmic, apexi filter, 255lph fuel pump. Goes well just with light mods.
Te whole thing about it being unbalanced with a heavy engine is crap I think, I drive mine daily and don't notice te difference.

[danb]

stock turbo has ceramic blades - its recomended not to put more than a bar of boost for it, there are plenty hybrid steel bladed turbos out there available (£800ish new) and people regulary achieve over 400 from them with the supporting mods.

Im only in wigan, and ive got a 25 in mine (not mapped yet though but will be soon )

ill be doing some track days early next year all being well - so will see how the engine how affects the hadnling.

[s13silvia]

Stock turbo oil seals sh*t themselves in no time. The enging is prone to ring-land failure too, plus budget in some splitfire coilpacks. With a GTR crank/rods/pistons and a heavy turbo they can really shift - but they are a fairly torqueless motor, just like the RB26- all about the revs. If you like this kinda engine, go for it. Clutches are expensive and once you up the power this cost skyrockets, I know guys who've spent 2+k on race clutches for them to f*ck up within 1k miles of normal road driving.

I'd consider sticking with an SR20det and tuning it, as it's a cheaper base and tuning platform though the gains may be a little less. If I had my way I'd dump my RB for a VG30, they produce shit loads more low torque than a 26 and cost pennies to buy/get to 400hp.

Edit - for anybody who thinks the VG is a pig compared to the RB25/26 check out pentroofs direct comparison between an similarly tuned VG30 and RB26, both with twin TD06-20g's

http://www.ooparts-international.co....ntroof/record/

RB26-759.9rwhp at 7820rpm / 75.1kg.m at 7000rpm
VG30-746.5rwhp at 6550rpm / 119.7kg.m at 4550rpm

[craiglancs]

Stupid question but what mpg do u lot get with a 25 in an s body, i'm guessing better than if it was in a skyline due to the lightness of s body? I only used to get 17mpg out of my NA supra otherwise i might consider an RB swap at some point

[igralec]

Compared to a stage 3a SR20, i'm getting 2.5MPG less on a standard map RB25 on same combined driving (urban and hard driving is a bit worse on fuel i reckon). If running the s14 diff the 15mph or so longer 5th gear helps motorway cruising at 80mph a lot though

[craiglancs]

thats not too bad then, but all depends on what u were getting on the 3a sr20?

[igralec]

24.5 in the SR and 22 on the RB now, that's around 30% urban (35-40mph), 60% extra urban (50-60mph) and 10% motorway (80mph)