Spec S - Engine swap options?

[Trial_S15]

I'm being tempted by the truely evil JP and I wanted some more info on my options. He rang me yesterday and said that he knows somebody who would be interested in buying my SR20DE for a project they have (and possibly the box aswell). I know there are loads of threads on here about SR20DET conversions but what about RB20DET'd S15's? - the reason I ask is because I'll be on a tight budget and they're reasonably cheap! (plus they're a bit different, 6 cylinder & will sound fantastic!)

If I sell my SR could I keep the box & diff and get the SR20DET from an S14a/200SX or will I need a new diff & box?

Alternatively, if I go with the RB20DET is there any benefit getting it from one model Skyline over another, what sort of power/torque could be expected from a standard unit & turbo and what is the best engine/box/diff combination I could go with? I was considering/hoping to go with the box from an RB25 (so I won't need to replace it again if I ever choose to up the power) and keeping my Spec S diff....

Also, how easily tuned are the RB20's? Similar to the SR20DET for eg?

All help is much appreciated,

Colin

 

[Trial_S15]

Loads of queestions I know!

I've done some searching and there appears to be one S15OC user in Peru who has done it but no project thread

I know the RB25&26 are quite heavy but I had hoped the 20 would be light enough as to not effect the handling too much. But reading this I think I may be wasting my time.....
http://forum.s15oc.com/showthread.php?t=3020&highlight=rb20&page=2

I don't want to go to the hassle and expense and be left with crap balance/handling, am I better off going with the tried and tested route & get a 14a DET - and if so how much of my spec S running gear can I keep?

 

[meddler]

talk to evilchap. He was the one that bought Nicely's S15 and is currently doing an RB26 conversion. As far as I know the RB26 engine is the same as the RB20. Atleast but an RB25 in it if you are going that way. I think an RB20 would be a waste. No real big gains, just some more torque and a different exhaust note. You may as well fit an SR20.

I personally would just fit the DET. Unless you are drifting or want crazy HP, the SR20 is more than enough.

 

[Trial_S15]

I've read Evilchaps thread on the sxoc, what a car! But doesn't the firewall need to be cut or something to fit the RB26? I figured the 20 would be a good bit smaller & easier to fit? It's also a significantly cheaper way of getting a turbo into my Spec S (as the 20's are held with as little regard by skyline owners a the DE is with Silvia owners so are going cheap) but as you said I'll probably be better off going with the SR!

Will I need to change my gearbox or diff if I went with a 14a DET?

 

[200WEI]

why rb20??? why not jus go for much newer sr20 turbo?? then u get ball bearing turbon its much lighter engine n most of all, they were made for silvia.

 

[meddler]

I think that all the RB seies are pretty much the same dimensions.

If yours is a spec S (SR20DE and 5 speed) I see no reason why you couldn't just bolt up the S14a engine to your existing gearbox. It was only the 6 speed that had a different flywheel, etc. Someone on here should be able to tell you 100% for sure tho.

 

[Trial_S15]

.....If yours is a spec S (SR20DE and 5 speed)......

Yup It would make it a lot easier if I could use my existing box & diff!

200wei; The RB20 because its cheaper and has a lot of potential. Plus if I did the conversion I wouldn't just have another DET'd spec S - But I honestly thought it would be a good bit lighter and smaller than its bigger brothers...

 

[slammedmind]

if you were going rb then the rb25 would be the only option, for the effort it will take to re-wire and fit the rb20 its not worth it. The sr20det is what the car was designed for, if i were you id hold on, save up forge it and put a nice gt-rs tubby on it then drop it in and enjoy it

 

[DeanS15]

sr20det would definely be the most cost effective in terms of what you'll get for your money. surely the rb20 as was said would be a bit of a waste of effort and the rb25 would be a bit more xpensive once everythings been dealt with, not just the purchase of the engine, box, loom, turbo etc. but all the extra things that would need doing.

there are bundles of breakers on the sxoc at the moment. why not take a look........few rb projects as well, finished and ongoing

 

[Trial_S15]

Thanks lads. I'll forget the RB so and see what I can get SR wise. So can I keep my current box & diff then?

 

[DeanS15]

depends what box is fitted to the s, but if its the same box as the r (6 sp) then you can keep it provided you remain with an s15 flywheel and clutch to fit to the sr. you can also keep the diff afaik, but if im not mistaken its highly recommended to fit the helical from the r.

 

[raytsang]

JP's got a helical diff hes selling..
yeah s14 engine or a s13 sr20det redtop... is the way i would go. lots of people crashing s bodies nowdays so should be easy enough to get your hands on one.

 

[Trial_S15]

It's a 5 speed box with a vicsous diff. So I can keep the 5speed and go with a 200sx (14a) clutch and flywheel then? I'd love to have the €2k asking and rob the complete running gear from that white Spec R which is being broken but by the time it was fitted that'd be megga money

Jp is selling a helical! He told me I'd be better off with the vicsous???? He hasn't rang me back yet though so I may not have a buyer for the engine afterall

 

[raytsang]

It's a 5 speed box with a vicsous diff. So I can keep the 5speed and go with a 200sx (14a) clutch and flywheel then? I'd love to have the €2k asking and rob the complete running gear from that white Spec R which is being broken but by the time it was fitted that'd be megga money

Jp is selling a helical! He told me I'd be better off with the vicsous???? He hasn't rang me back yet though so I may not have a buyer for the engine afterall

the guy at the last meet really wanted to buy a n/a sr.
sell that and invest in the sr20det garanteed best mod ever. and saving yourself money not tuning the n/a.

engine swap would be pretty much plug and play.
so if you can get him throw in all the part for 2k..
-ecu harness
-ecu
-engine with turbo
-tranny, clutch fly
-intercoooler
-wiring harness for boost gauge and probably boost gauge.

it should be a straight forward swap... sure stiv would have it all done in a day.. he charges resonable money too.
swap jp engine many a time no bother. give stiv a shout he give you better info and a list of anything else im missing.


and about the diff.. its up to yourself what your comfortable in.
JP's just so use the viscous.. the helical feels odd to him.
might not be so with yourself.
alot of people on this site have driven the viscous diffs on s14 and swap over to the s15 with helical and love them.

for drifting the viscous is better i heard.
helical is torque driving so can throw torque from one side to the other when confused. but it really all down to your driving.

 

[Trial_S15]

Cheers ray, thats probably who JP was on about then but no word yet.....

I'd love to buy James' engine but 2k is well out of my price range, epecially now that we've been told we're taking a pay cut in work :annoyed:

Ah well, back to dreaming about more power

 

[s15andy]

Mine was an an auto spec-s and i found an early low mileage s14 engine and box and stuck that in. Bought it as a front cut so i could take everything out myself, i wouldnt fancy doing the wiring having not seen how it came out! You will find a thread on here somewhere about others doing the conversion without the aircon and abs. I wired mine in fairly easily, just so you know if yours is used as a comfy road car.

If you want any more info give me a shout

 

[Trial_S15]

Cheers Andy, Jp's buyer can no longer afford the project though so I definately can't afford the swap at the minute (TBH I was kinda fooling myself as it was). She is my daily though - no1 could accuse her of being comfortable with the HKS coilovers & Nismo bushes but I do need the air con.......

 

[silv15]

Hi, im the one who swapped a RB20det on my s15 spec S.
As I said on my old post, i was first looking for a RB25....Ive allready found it and swapped it allready, ill post pics when i can....it was the same as fitting the RB20, has the same dimension, etc etc, no firewall was cutted....I had to upgrade my brakes to Evo 7 Brembo...because of the engine weight.
My car has the next upgrades.

Rb25det from nissan skyline r33 from 1998
20002 R34 gts-t Gear Box
HX35 Holset turbo at 25psi
GREDDY R33 Intake plenum Manifold
100mm throttle.
Header.
850CC SARD inyectors
forged wiseco pistons
rb26dett rods
Nismo suspension.

it will get out from the garage in about 1 month.....i will post videos and pics of the swap...hopefully i will get 550 hp at 25 psi or more

 

[Matt_S]

RB20 is old hat and not that easy to get uprated parts for.
You dont need to cut any firewall, just bang it about a bit for fitting RBs on the Skyline Crossmember.
THe std DE box is OK but doesnt have the uprated bearings that the S14 DET box has as std.

 

[Trial_S15]

Would be interested in seeing the update on that Silv15 :thumbs:

Thanks Matt, is the viscous diff the same job (ie not as good as the S14 one)?