Tuesday, 8 February 2011

RB Power

Fast forward almost one year (!). Didn't have time nor money (in the proportion of 40:60) to continue :/ I couldn't work on the car, but I compensated by doing a lot research. And guess what, plans have changed. This is going to be a 300 - 400 hp track car.
Upgrading the L24 engine is not an option, at least not outside the US or Japan. Nothing useful to find here to crank out that much hp. Considered a Toyota Supra engine at some point but I preferred to keep it all Nissan. The 350Z engine would be an option but that'd be too much hassle and definitely not cheap. But way cool. Imagine a first gen Z with a nu-gen heart :)
After a lot of research I finally decided to go RB; with some mods RBs fit perfectly in the Z. And with some more mods you can crank out hundreds of hp. While most people go the RB25 or RB26DETT route, I've decided to go RB20DET, or have I? An internal debate is still ongoing...


Why RB20DET:
  • use the standard RB20 mounts with minor modification rather than spend top $$ on expensive motor + tranny mounts ($475 at Mc Kinney motorsports)
  • no expensive custom made drive shaft ($450 at Mc Kinney's) but use the stock drive shaft instead
  • use NISTUNE with the standard ECU
  • wiring is supposedly not too complicated
  • can be had for less than 2000 euros
    RB25DET NEO at least 2450EUR, RB26DET 3750EUR
  • in stock form it delivers around 220 hp which is almost double that of the L24 :)
The only thing I'd need is either an oil pan from a Nissan 200ZR (a Z31 with RB20DET, for Japanese market only, p/n 11110-20P00) or a $500 custom made pan.

In standard form RB25s or 26s can deliver more power and torque, but the RB20 swap is a lot cheaper and easier. With a bigger turbo and injectors, over 500 hp can be achieved! That's nuts on a Z! But like I said before, I'd settle for 300 - 400 hp, which can be achieved with relative ease.
To increase torque, I might consider stroking it and make it a rev crazy RB23/24 :) To make an RB23, I'd need the crank and rods from a RB26, and the Toyota 4AGZE pistons. Using the Tomei piston kit I'd get an RB24. Going beyond a 81mm overbore is not recommended though.

Another testimonial: "RB20s are NOT junk they are very well balanced engines. If you want to dump money into it you can go with a rb26 crank and rods. Bore it 3 mm over and the typical thing to do is use toyota 4agze pistons, and you will have a displacement of 2.4L. Use aftermarket forged pistons and the setup is bulletproof. The only thing you can do for the head that I know of is going with a 26 valve spring and lifter setup. With this valve train you can run stock 26 cams or go with a set of kelford cams 272*. I rebuilt a rb20 in a s14 mid last year for a customer, using stock pistons with the bottom end being re-ringed and new bearings, with a gt30, intake & exhaust manifolds, cams, and a power fc at 18 pounds put 388 to the ground. Porsches and BMWs are no match at road atlanta!"

RB20 stroker
info sources: 1, 2, 3
What follows is a compilation of information from various sources on the subject of stroking an RB20DET.
From Skylines AU

RB21/22/23/24
  • RB21: RB25 crank + std 78mm RB20 pistons
  • RB22: RB25 crank + std 81mm 4A-GZE pistons
  • RB23: RB26 crank + std 81mm 4A-GZE pistons and rings
  • RB24: RB26 crank + 1.5 mm oversize 4A-GZE pistons
    Note on 4A-GZE pistons:     RB20/26's gudgeon pins are 21mm. 4A-GZE pins are 1 mm smaller (20mm); use a bronze bush in the rod bored to the correct size. 
  • ACL bushings
  • ACL RB26DETT bearings
  • RB26 connecting rods
  • RB26 big end bearings
  • Aftermarket oversize RB20DET head gasket
  • RB26 oil pump
  • RB26 water pump 
  • RB20 head with GT-R valve springs

Stroker kit

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