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RB Enthusiast
644 Posts
Discussion Starter #1 (Edited)
Nizmodores S13 RB Swap Sticky Part1!

"Collecting the bits"


O.K there is a lot of intrest in putting Skyline/Laural Engines in the S13/240SX Chassis. I'm going to run through a mostly fool proof list of what you need and what options you have in installing a RB engine into your car....

I'll be going through things like engines (duh), gearbox options, cooling, Drive lines and mounts etc. And please I would like to keep this sticky clean so don't post silly questions on it. If you have any questions or things you would like to add PM me so I can add it! ;)

BTW I've only done this to a JDM S13. The American 240SX may be diffrent in some regards, and since I don't live in America, I really don't know what they are (Besides LHD and the KA engine)

Well, here goes! :D

List of external bits:

Parts options. Here are the three lists of what parts you can use to make your "hybrid" car....

Part 1, RB engines:

There are many types of RB engines, not just the famed (or infamous) RB26DETT. While the RB26DETT is the "pick" of the RB engines as far as paper peak power outputs are concerned, it is also the most expensive. I won't include engines like the RB30E, RB30ET, RB20E, RB20DE and the RB24-s simply as they are not viable to put into your S13, due to age, and power outputs. Eg the RB30ET produces more torque and slightly less power then the RB20DET, yet its a older engine than the S13 chassis, and in some countries like Australia, you can't put a old engine in a later model car due to emmisions regulations (well you can, but you won't get it Registered).

I also havent included the RD engines, which are really RB diesels....If you really wanted to be diffrent a Turbo diesel S13 would rock ;) I'm supprised this hasn't been done...oh well! :p


The RB20DET is the smallest of the RB engines. It produces around 153Kw @ 6400 rpm and only 265nm @ 3200rpm of torque. These engines come with a small intercooler and this needs to fitted in order for the engine to work correctly. You can live without the intercooler, but I'd suggest that you alter your turbo's wastegate control, so you don't run as much boost. While they are a good reliable and powerful engine, you REALLY need to push them hard to go anywhere fast. I've done a few swaps with these engines in VL Commodores and they are not really what I would consider a forward step from the RB30ET's they had in their cars to start with.

Also, I've been hearing about a RB20DET stroker kit that takes these's engines out to 2.4 litres. I have no experience with the stroker kit so I won't comment on how good they are, but needless to say I would imagine you would get a bit more off boost/low down torque with the stroker kit fitted...

Another thing to remeber is there are 3 versions of the RB20DET, the old NiC's Version and the later ECCS versions. There are two type of the ECCS RB20DET motor, the red top and the black top. Some people claim one is better than the other, but I call a spade a spade, and to me a RB20DET is a RB20DET!


Just because there is no turbo doesn't mean these engines don't go hard. With 145KW @ 6400 rpm, it produces slightly less power than the RB20DET. Useful if you can't get a turbo charged car insured and you still want a RB engine in your car.....Hmmmmm ;)

While it produces less peak (remeber peak) torque than the the RB20DET only 319nm @ 4800, its torque band is much broarder (this from experience, I can't give you dyno evidence!). This makes it a much more drivable engine. This engine uses the same bore size as the RB26 and RB30 so you can use pistons from the larger engines if you want (useful if your adding a turbo to it and want to drop the compression ratio)

Another thing to consider is, if you wanted to you could create a "hi compression" RB25DET, useing a RB25DE as a base and adding turbocharger from a RB25DET. This engine would be waaay more drivable than a RB25DET, yet produce less power on the top end (Rice boyz who live off their Dyno sheets need not apply!) In english High compression = less boost can be run, but engine comes into its power band faster, due to more off boost torque!

There are two versions of the RB25DE, one with VCT and one without. The only diffrent, it the VCT version has a better torque spread, and the extra control gear for the VCT on the engine....easy stuff really!


Some people think this is the best engine of the RB's for price to performance. With 187kw @ 6400rpm and 294nm of torque at 4800 rpm this is one good engine. They come standard with VCT, and require a larger intercooler than the RB20DET in stock form.


What can I say? The infamous RB26DETT, with its twin turbo's is every import drivers dream (well most, I know a few exceptions like myself!)

The Stock R32 engine has 209kw @ 6800rpm and 368nm of torque at just 4400rpm! Some people belive these engines came with a stock power output of around 230kw rather thaen the factory quoted 209kw....

The main diffrences between the other RB engines and the RB26, besides the 2.6 litre capacity and twin turbos is the use of solid lifter rather than hydraulic ones, and the head has much larger inlet and exhaust valves.

Hybrid RB engines:

There are also Hyrbid RB engines than can be built, useing a combination of parts from all the RB serries of engines besides the RB20E/DE/DET due to a driffrent bore size...


The RB30 serries of engines were contract motors that were designed for a Australian Company Holden to put in their VL serries Commodores. In short this means unless you live in Australia/New Zealand I wouldn't bother, unless you really wanted to be diffrent. A RB30E can be picked up for around $300 AUS, so if you factor in freight to the states it may be affordable....

The RB30's never go twin cam heads, however due to the fact that they share the same bore size of the RB25 and RB26 means that you can put one either one of these heads on a RB30E/ET block to produce a "hybrid" engine.

Stock power outputs of these hybrids are very hard to tell, due to the fact that they often go with aftermarket turbochargers, ECU's and very rarely use standard size intercoolers. However due to the fact of a 3 litre capacity I would imagine that they would produce far more torque at low RPM than any other of the RB engines, the RB26DETT included. eg the RB30ET non intercooled, SOHC turbo engine produces 296NM of torque at 3200rpm....cripes!

The use of diffrent heads also impact on the "hybrid" engines performace. eg the RB26DETT head with its huge inlet and exhaust valves and solid lifters is the best head to choose as far as power goes, but also the most expensive. A good choice is the RB25DE non turbo head, this head will give you a good boost friendly compression 7.8:1 when but on a stock RB30E engine.

When building a Hyrbid RB30 Twin cam, you need to relocate the cam belt tensioner and use a longer cam belt. If you want more information, please go here:

RB Enthusiast
644 Posts
Discussion Starter #2 (Edited)
Part 2, Gearboxes:

There are two main types of gearboxes for use on RB engines. I haven't inlcuded the 4WD Skyline GTR gearbox, due to the fact that most people who want a RB engine in their S13 don't want to go to the trouble of installing the 4WD system.....

Nissan FS5/MF5:

This is the stock gearbox that comes with the RB20 engines and the non turbo RB30 engines. The MF5 has single ring syncros while the FS5 has twin ring syncros on 2nd and 3rd gear, which means they take a bit more punishment, before they cry "enough!"

Compared to the larger MX7/R33 skyline gearboxes these are very weak units, however they will survive upwards of 220RWKW without too much trouble. The main problem people have with these gearboxes is when you start adding ceramic clutches. DON'T USE CERAMIC CLUTCHES ON RB20 GEARBOXES!!!!!!!!! Have I got my point across?

As with all Nissan gearboxes, they share a common design fault of the output shaft bolt comeing loose, allowing 5th gear to get destroyed. So If your going to put one of these boxes in you car I'd suggest you pull the rear houseing off and tighten up this bolt....not too hard really.....

Also these boxes dont have a syncro on reverse gear, so don't go jamming them into reverse while your still moveing forwards..please! I've seen a FS5 gearbox with the layshaft completely snapped off becasue the owner did this...well he selected reverse instead of 4th at 6500rpm but still!

Nissan MX7/R33 GTS-T:

Same as before, The MX7 is has single ring syncros, and the R33 box' has twin ring units. Only this time the R33 has twin ring units on everything! these boxes are built like a brick s**thouse (aussie term) and take a heap of abuse.
And yes you can use a ceramic clutch on these puppies...happy? ;)

Also as before 5th gear dies due to the output shaft and layshaft nuts, do 'em up!

Another thing, is these boxes are much larger compared to the the MF5/FS5 gearboxes. So if you install one in your S13/240' you may have to "massage" your trans tunnel with a hammer (I know it sound grusome) to get it to fit. Also they run a diffrent starter motor and flywheel (flywheel is much larger, thats for the bigger clutch!).

You will also require a diffrent, larger gearbox crossmember. You have been warned....

This shows the size diffrence between the MX7/R33 box and the FS5/MF5 gearbox. Image provided from Kneedrager from the Calaisturbo fourms ;)

Jatco Automatics:

Yes a auto. Only loosers drive autos? Rite? WRONG! Remeber automatics when they change gears keep the engine on boost. You may loose 10RWKW on your dyno sheet with a auto but you have a faster 400m time....

If your going to have a huge motor infront of your auto I'd suggest a large transmission cooler, try and source one off a large domestic American V8 with a automatic trans.

Also I'd recomend, a 2500rpm Hi stall torque converter, and a manual valve body. The valve body is optional, but with a high stall expect to drop some time off your 400m passes. If you really wanted to be insane, you could go with a 5000rpm histall and launch your front wheels...hmmmm ;)

Othermods, include uprated internal clutches and friction lineings, larger drive pistons and servos (2nd gear), and your input and intermediate shaft upgraded, either by heat treatment, or replaced by hi tensile this time you'll have no trouble running over 500RWKW through one of these gearboxes....

Nissan automatic gearboxes have a diffrent tailhaft yoke compared to the manual gearboxes, so you'll need a diffrent tailshaft if you want to go auto!

RB Enthusiast
644 Posts
Discussion Starter #3 (Edited)
Part3, Tailshafts and Diffs:


As I just said, the yokes on the auto and manual Nissan tailshafts are diffrent. Also some people say you need to shorten the tailsahft I never ran into this problem, depends on maybe what cross member you use for mounting the engine? or Maybe the 240SX unit is shorter?

Also the Larger MX7/R33 gearbox requires a diffrent tailshaft yoke, compared to the FS5/MF5 gearbox, just to make things VL Commodores which came with both of these gearboxs it is said that you need a difrent tailshaft for the larger have been warned....


The standard IRS diff on the S13's will live, however, I strongly recomend a LSD if you don't have one.

Other stuff you need!


The SR20/CA18 powered JDM S13 Silvia's require the fron subframe to replaced with a R32 Skyline in order to accept the Nissan RB engines (diffrent engine mounts). While the KA powered versionI'm told (remember I live in Austalia, I've never seen a 240SX!) will accept a RB engine with no mods....

Gearbox crossmember:

I prefer to fabricate a custom crossmember, rather than re-use a Nissan Item, I'm told (again 240SX not S13) that the 240SX member will bolt up backward to allow the installation of a RB gearbox....

Fuel System:

The stock fuel system will be fine, however I'd recomend the use of a external fuel pump as well as the internal pump, and please mount a fuel pressure gauge on your fuel rail, so you can see if you have any problems. It helps solve a lot of time when your trouble shooting!

Computer Loom for engine/gearbox:

Two options. Build a new loom from scratch (Like me) or splice a old loom. Your choice really!

Cooling System:

Some peole belive you have to extend the nose of the S13/240SX to get a RB to fit....wrong! :D While you cant use the stock clutched fan on front of the motor, you can install a pair of low profile thermo fans, they'll do a great job. Also people say you need a bigger

Radiator! Well I didn't in the swap I did and it hasn't had any overheating problems....

Other mods:

If you use any twin turbo RB engine, you may have issues with the rear turbo, fitting. I'd suggest that you fabricate a new turbo manifold, and move the turbochargers forward....

Also some people say you need to get rid of your bonnet supports (subframe) to allow the bonnet to shut correcty....


In summary:

Well thats all you need! Simple! Wait till next week when parts 2 and 3 come! Please, Please don't post on this thread untill I have posted all 3 parts (I've got a feeling nobody is going to listen to that, you post, you die!), and if your a admin, can you make this post a sticky? Thanks :cool:


134 Posts

This is one of the best pure tech threads i have ever read. Excellent work! I have deleted all other posts in this thread. It will be locked, but remain a sticky so that no other useless crap is added!

Once again...excellent work. This is the type of posts that make tech forums really beneficial!! You just got a big bump in your reputation points on this board from me!!

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