Built rb20 or stock rb25?

[Skym]

I think the HKS 2540 is quite response (or GTRS) on RB25DET -

http://www.youtube.com/watch?v=rYa1Ux4qOwM

[burton160]

I'm putting down 330 rwhp and 300 torque in my rb20... I have jun cams, pistons, rods, valves and valve springs, n1 oil pump . 3 core rad and intake, hks exhaust, gt2871r turbo for quick spool. I've beat stock gtrs but it still lacks in lower end good on small tracks. I would go rb25 if your looking for over 400whp.

[r33_gtst]

I'm putting down 330 rwhp and 300 torque in my rb20... I have jun cams, pistons, rods, valves and valve springs, n1 oil pump . 3 core rad and intake, hks exhaust, gt2871r turbo for quick spool. I've beat stock gtrs but it still lacks in lower end good on small tracks. I would go rb25 if your looking for over 400whp.

Well put

[krystalized_jdm]

I'm not looking for a monster build. Like I said, this is around the 2k budget. So either a stock rb25 or a built rb20.

At this point I am convinced rb20 is my best choice. From what people have said, and skym's awesome responses I think that a semi-built custom engine is better then a bigger stock engine.

Still appreciate the responses, thanks guys

[krystalized_jdm]

This is what I'm thinking of a parts list for my rb20

Not including what I already have. This is what I want to add/upgrade


- rb25 turbo
- wahlbro fuel pump
- Exhaust
- Nistune or stand-alone ecu
- fmic
- possibly an oil cooler

Does anyone else recommend anything? How do the rb20 stock injectors hold up under higher demand w/ mods like this?

[Skym]

Don't forget sparkplugs, NGK PFR6A with 0.8mm gap or PFR7A if tuner recommends it (or are running a leaner A/F ratio) or NGK copper equivalent, clutch upgrade. I would swap turbo for Deatschwerks 550cc injectors, and Walbro for Deatschwerks 255lph fuel pump, Deatschwerks hardwire kit (don't forget new O ring from Nissan for cap where fuel pump is located) and upgrade turbo when it fails and add Z32 MAF + Z32 MAF plug.

Not ideal (270cc factory injectors), but they work up to 380hp max with bigger fuelpump, 100% duty cycle (don't want to go above 80% duty on racetrack, but on road can get away with 90% or so like done with factory injectors), ECU tune. Around 270-300hp is as far as I would push stock injectors (with stock fuel pump). Engine oilcooler is a must have mod.

I've beat stock gtrs but it still lacks in lower end good on small tracks.

Use gears. Drop down to lower gear and keep rpm needle into powerband. That's the way the GTS-R racecar with RB20DET-R, small powerband was driven.

[r33_gtst]

Why use an rb25 turbo? You won't get good numbers or good top end with that set up
Turbo can't take much past 12psi, has its limits.
A smaller Garrett/holset/precision/turbonetics with upgraded exhaust manifold, intake manifold, injectors and exhaust would be all you need if you want a responsive car. Don't be afraid to turn up the boost, with a good tune and turbo you would be surprised how well it will drive

[burton160]

ohh forgot to say i have 550cc injector and a walbro fuel pump. Id definitely recommand a fuel regulator and an oil cooler as skrym said. Just got one myself waiting on lines though.

[Skym]

I agree with FPR (new stock or adjustable Nismo), but new stock FPR is cheaper and should do the job. Fuel filter, fuelhoses, new injector loom are the others that are usually replaced at same time when changing injectors for reliability.

You can get away with adjustable FPR, fuelpump upgrade (as used on that R32 Targa car), but it's a band aid fix to the proper way which is upgrading injectors.

[garetth]

I've went the built rb20 route and from personal experience I ran 3" straight pipe, GTR Injectors, z32 maf, Nismo FPR, VG30ET Steel wheel turbo, rom tuned by Carl H from nico forums and other supporting mods. And I can tell you that running it as a street set up wasn't that much fun especially drifting technical corners hitting 15 psi around 4-4.5k rpm I'm sure with a proper tune it could have been down to 3500 rpms but the only bigger turbo I'll ever put on a rb20 again is a rb25, rb20 high flow or HKS 2530.

[supersayianjim]

so, how hard is swapping a rb20 harness to a rb25 engine?? i have a nistune rb20 ecu. would i have to change this to work with a rb25??

[nick-nismo]

The swap is really easy I just did it. Depending on what injectors your using you will have to wire in pig tails to match. No rewiring at ecu either. Then use the rb20 ignitor and coil pack harness on the rb25 for plug and play.
I say get the rb25 then build that down the road. There is soo much more low end power with the 25 it makes the car much more street able.

Edit. Also if you use the rb20 trans you can use stock r32 Gtst drive shaft

[Skym]

I've went the built rb20 route and from personal experience I ran 3" straight pipe, GTR Injectors, z32 maf, Nismo FPR, VG30ET Steel wheel turbo, rom tuned by Carl H from nico forums and other supporting mods. And I can tell you that running it as a street set up wasn't that much fun especially drifting technical corners hitting 15 psi around 4-4.5k rpm I'm sure with a proper tune it could have been down to 3500 rpms but the only bigger turbo I'll ever put on a rb20 again is a rb25, rb20 high flow or HKS 2530.

From what I understand, VG30ET turbo has a bigger A/R exhaust housing that makes it laggy. Hybrid RB20 turbo uses same internals (same TB03 CHRA and I think same size wheels) but with smaller A/R R32 RB20DET housings (bored out to suit bigger wheels). From memory peak boost (around 15psi) for HKS 2530 is around 4000rpm on RB20DET with split dumppipe. Adjustable camgears, stronger adjustable internal wastegate, good tune, boost controller, 3" bellmouth exhaust from turbo, etc can help to bring that down, get better boost response.

With ECU not tuned on car, a ECU tune like that (generic tune / tune used from another car or done on computer without touching car) wouldn't work very well and have a small hp gain. Generic chips never work right unless using exactly the same mods (factory setup is one example) and tuned on dyno, etc. Even then the power varies due to internal wastegate at slighty different psi on each car, etc.

RB20DET Greddy TD06 turbo kit with adjustable camgears, ECU tune, supporting mods like injectors, fuelpump, etc on dynochart has the same power curve as RB25 turbo but get higher peak hp.

This Skyline has that TD06 turbo kit, etc -

http://www.youtube.com/watch?v=LV-bcbzwrpg

Not cheap, but get the result's you want (over 400hp at engine with good powerband).

[magular]

Hey not trying to barg in, seems like I'm in the same boat as the person who is making this thread. I've read all comments, but someone said not to go bigger then rb25 turbo on rb20... Really that's the max? I mean not looking for big power anyways but I assume for response and not as good low end I guess makes sense, but getting a high flow rb20 or rb25 turbo, wouldn't they spool a bit quicker with the benig rebuilt and a but more capable of being safe at 15 psi instead of the usual 12-13 psi on stock turbos...?

Just few things maybe get cleared up for whoever else might was wondering similar.

[G-E]

"Big enough" and "too big" are really subjective, and a vg30et turbo is by no means big and laggy on a 2L, also they can be rebuilt into a 60-1 with a stage 3 wheel cheaply if you just want a lot of boost

Your driving impression all comes down to tuning and supporting mods, you can also free up hp from accessories, e-fans, e-wp, lighter flywheel, lighter wheels etc...