ARC240's RB20DET 240SX Build

[ARC240]

Hey guys, I bought my 92' 240SX fastback about 3 years back. I've always loved both the S & R chassis, with a special liking for the RB-series engines. I knew for sure that whatever I bought was going to be a Nissan of some sort and while car shopping, I bumped into a few R32 GTS-t's. The ones that I came across weren't in the best of shape, but I took a special liking to their RB20DET powerplant. So, I figured the most enjoyable setup for me would be an S13 240SX with the GTS-t's RB20. Around a year after I had bought the car, I had done my research and acquired enough cash to do the swap...but, I made the mistake of handing my swap over to a shop (would have done it myself, but I figured a shop could do it more quickly and would have the proper tools), something which I will never do again. The owner of the shop assured me he knew what he was doing and that he was experienced with the RB-series engine...only to find out midway through the conversion that my project was the first RB into 240SX he had ever done . After receiving the car back from said shop (with the RB20 barely limping home and running on 5-cylinders no less), I was fed-up with the crap from that shop, so I decided to start digging in to the engine myself. All of last winter was redoing the entire engine harness that had previously been botched beyond belief and making the engine run properly. I had it running perfectly last summer, passed emissions with flying colors and had so much fun.

I've really wanted to do a built RB20 for a long time, so this year, she's getting a refresher. In the end I'd like to make around 400-500hp, so, for the sake of safely building that kind of power, having peace of mind and fulfilling the want of a built RB20, I decided to haul the engine out and rip it down to the block. I realize that building a high horsepower RB20 isn't the easiest, but I'd like to see how far I can take it. I'm not planning to hit my horsepower goal right away, I'd like to take it slowly as I do with all of my modifications, I find that I enjoy it more that way and I can pay closer attention to detail. The basic parts outline for the build as of right now is predominately focusing on the bottom end, after the bottom end is built exactly the way I envision it, up the boost a little bit more (not much, I may boost around 10-12psi just for now, make fueling provisions and then move onto the head, which is said to be the weak spot of the RB20 and do everything I can to allow it to flow better. If anyone has any questions or if you want any information, feel free to PM me, I'd be more than happy to answer your questions.

So...to start you off, here's what the engine looks like as of now. I've taken the cylinder head off and have begun bringing the engine down to its primary components. I expect to have the block completely gutted and off for honing within the next few weeks. Keep checking back!
Thanks for looking guys,
Enjoy !

Mark (ARC240)

What the engine looked like in early January


Here are the pictures as of today

[SEANISSAN_GTS-T]

i'm just starting the exact same thing, just got the block and will start ripping it tomorrow, going for around the same power, what are your build plans?

good luck,
sean

[Skym]

Cool project.

Group-A RB20DET engines produced 370hp, 400hp, 450hp. Gibson racecar had 370hp and 450hp when fully developed. In Europe it was around 400hp.

I'm aiming for around 340hp (low boost) - 370hp (high boost) with my cars engine, due to hp level that can be put to the road with less wheelspin. You'll want to aim for 400hp max at engine, due to gearbox longevity (safe hp limit).

Roy's R32 GTS-T is producing around 372hp at engine (230rwkw / 308rwhp) in this videoclip -

http://www.youtube.com/watch?v=y2az4jeRzvg

For 500hp, requires alot more mods like upgraded gearbox, drivetrain, etc for reliability. That's why most buy a GTR, as it easily makes 460hp-500hp with similar mods and has a reliable drivetrain + can put hp to the ground with 4wd.

Also you might want a JUN crank collar (or similar). JUN crank collar instructions -

http://www.skylinesaustralia.com/forums/Jun-Crank-Collar-Instruct-t130430.html

Also change the valvesprings, valve guides, seals, etc while head is off. It's alot easier to change them when head is off. Then when it's time to change cams (can afford to change them), just remove stock cams and fit new cams with engine in the car. Basically don't need to remove head again.

This is a 364ps RB20DET build in Japan. Engine has a HKS 25/30 turbo (includes dynochart) -

http://skylinist.blog.eonet.jp/hcr32/

Specs of engine are down the bottom of page.

This S13 has similar mods (cams, turbo. etc) as the 364ps RB20DET, so gives you an idea of what it drives like with that amount of hp -

http://www.youtube.com/watch?v=LKVqmzp1piQ

He list's the mods (S13) on top of right side in this videoclip -

http://www.youtube.com/watch?v=jyEp5WHZu1E&feature=related

[RABBIT]

cool build , i realy want to see this thing

[BurlyR32]

Roy's R32 GTS-T is producing around 372hp (230rwkw / 308hp) in this videoclip -

http://www.youtube.com/watch?v=y2az4jeRzvg

I believe hes still running stock internals on a TD06-20G, emailed him some time last year. 325whp

[Skym]

From what I can remember, stock engine. He said in the comments below another one of his videoclips, that it had around 230rwkw. The 260rwkw (or roughly 400hp at engine) is at a higher boost level. The 260rwkw plot would be on the dyno chart in the RB20DET dyno result thread.

[jessem]

From what I can remember, stock engine. He said in the comments below another one of his videoclips, that it had around 230rwkw. The 260rwkw (or roughly 400hp at engine) is at a higher boost level. The 260rwkw plot would be on the dyno chart in the RB20DET dyno result thread.

any idea what kinda boost hes running?

[SEANISSAN_GTS-T]

skym, when you said 400 was the limit did you mean of the rb20 tranny? because i'm am planning on using the RB25 tranny for 400 whp

[love_boost]

nope thats for the motor and imo 400whp is pushing the envelope on an rb20?

good luck with the build! definatley be nice to see a built rb20 around

[Skym]

Not pushing the limits, some RB20DET racespec (forged) engines had around 420rwhp all the time.

Roughly 400hp at engine is the "safe limit" that some tuners use for stock RB20DET gearbox. SR20DET gearbox is the same, most stick to 400hp. On dyno, stock RB20DET, SR20DET gearbox can handle more hp. But when loaded up on the road or racetrack with cars weight and semislicks (you'll need good tyres), they can fail.

SR20DET gearbox has the Nismo upgrade option. RB20DET gearbox has a aftermarket upgrade option, but is not cheap.

The option that most with high hp RB20DET's use is stock RB25DET gearbox, stock GTR diffhead, stock GTR halfshaft's, GTR subframe, custom propshaft.

Roy's car mod list is in this RB20DET dyno result thread below -

http://www.skylinesaustralia.com/forums/Rb20-Turbo-Upgrade-Dyno-t103095.html

I think it produced around 20psi with 260rwkw. You would have to ask him to be 100% correct, as dynochart is not there anymore.

Here's the latest videoclip from dude who owns that 364ps RB20DET -

http://www.youtube.com/watch?v=JuRmNDgezuk

Wow, the car hauls.

[plankworx]

semislicks (you'll need good tyres).

Truth. Random wheelspin in third when you're goosing it on the highway isn't very fun when you dont expect it. 350+hp really makes the gts' traction issues obvious.
That said, if you WANT to break 'em loose on the highway in third, it's a hoot and a half.
Good luck with projects.

[BurlyR32]

I'd say your best option is to pick up an R34 GTT Tranny. Apparently one of the strongest RWD trannies nissan makes.

[ARC240]

Alright guys, I know it's been a while since I've updated the thread, so here it is, there will be more updates to follow today.

I've managed to strip the block entirely. Looks as though I'll need new oil jets though, 1 became very brittle and cracked . Pistons, rods, crank, oil pump, sensors, everything is off of the block.

Here's the RB20 block getting ready to be painted, this was about 2 weeks ago.


Freshly degreased, powerwashed & pat-dried (exhaust side).


Intake side after degreasing & powerwashing.


Picture of the 6 lonely bores.


Mmmmm...wet paint , decided to spray the block in a super-matte cast-iron paint, this is really, really heavy duty paint, I used the same thing on my exhaust manifold and it simply refuses to let go of metal. You can't tell it's true color when wet though, looks super glossy before it dries completely lol.


Parts I've collected so far for the build, which include: Tomei metal HG (thanks to Adam @ Feast ), OEM Nissan gaskets, nuts & bolts (replacing just about every nut & bolt on this engine with new stuff), crank timing gear and plates, Nismo T-stat, HKS cam gears & Nismo Timing Belt (were on the engine before the build), NISSAN frost plugs, TiAL 38mm wastegate & Turbonetics turbocharger (will release turbo specs later, bought both of those items last year, didn't have the funds to finish the project, being optimistic about it this year lol, not 100% if this turbo setup will actually be installed).


Updates:
- Forged H-beam conrods should be here by tomorrow/Tuesday
- Custom forged pistons are almost done being made, went with a +0.5mm overbore, should be here withing the next few weeks!!!
- ARP head studs should be here this week as well!

**Looking for a top-mount manifold to suit RB20/25, should be in good condition, if you (or anyone you know) have/has one, send me a PM, must suit a T3 turbo exhaust flange.

As for transmission, I'm not going to bother swapping anything until this transmission kicks the bucket, still has tons of life in her and shifts extremely smoothly.

More parts still to come, still looking for a hefty racing oil pump (JUN/Tomei).

[RABBIT]

cool looks like we have very similar out looks for our engines, only differences is drive train and body lol

[FITZY_07]

Mark man its looking good buddy!
I forgot to ask you what are you running for managment? And who do you have in mind for tuning?

Must be pretty excited man...