RB FAQ

Canada Nissan Automotive
1

we know the rb26 is top, and the rb20 is bottom. Lets just shoot some info out on all the engines to help other people decide on engines. Also lets leave price out of comparing engine to engine cause that always turns into the deciding factor anyways. Everyone shoot there feelings or good info on a specific engine. I can edit it in to make it easier. try not to get in arguments. if you disagree just say so. no need to make a fuss about it. Mod is gonna be strict on this one to make it clean. *this is just trying to make things a little easier for other people

General

Pros
-its an RB! from a skyline!
-closest thing to a real skyline
-I-6 potential
-the awesome sound.

Cons
-Yes, it is more weight, around 150lbs more for a rb25 swap. the weight isnt important tho, its the weight shift. it really depends on engine/transmission and how you mount it (i.e. crossmember or aftermarket mounts), but realistically your looking at 2-3% overall weight shift. if you look at the numbers in a 3000lb car thats only a 60-90lb shift forward. just to put that in perspective, 12 gallons of gas weighs roughly 100lbs so there is more of a shift between a full and empty tank, than a RB swap. IT DOES NOT DESTROY THE WEIGHT BALANCE OF THE CAR

-Parts are still rare and expensive, but things are starting to come over
-mounts or crossmember swap required

RB20

Pros
-cheap
-skyline engine (?)
-WD-racing was saw near 400hp with his
-easy swap
-free revving up to 8k is possible on stock valve train
-excelent gas mileage off boost (it is a 2l after all)
-can make good power with minimal mods.
-sensors interchange with lots of usdm cars

Cons
-SR is easier with same potential (for your lower goal people). out of the box both will make near the same power, and upgrade easily to near the same numbers.
-cheap turbo (ceramic wheel)
-“weaker” tranny, nearly the same as KA/SR trans
-akward intake manifold

  • its getting old 89-93 production years
    -high mileage engines need proper mantinence ie timing belts and water pumps
  • tiny injectors (270cc)
    -intake manifold flange is diffrent from rb25 (greddy manfold does not bolt on)
    -some rb20’s can have the same problem as the early rb26 engines with the crank collar issue
    RB25

Pros
-good potential (500+ on stock internals)
-VVT
-strong tranny (also include this when you price rb25s)
Cons
-expensive clips (when you get that strong tranny)
-becoming rare and expensive parts
-weak pistons ring lands
-not full glory as rb26
-another lame turbo, but better than the RB20’s
-factory hp overrated (easily achieved with basic swap upgrades though)
-side feed injectors (hard to find)
-akward intake manifold
-custom driveshaft required (unless you use RB20 tranny?)
RB26
Pros
-the GODZILLA of RBs
-most potential of all
-twin turbo stock
-upwards of 300+ out the door
-bullet proof
Cons
-$$$$$
-$$$$$
-r32 crank coller issue (kills motor)
-need for rb25 tranny
-hard to find r33 motors
-impossible to find r34 motors
-did we mention $$$$$?

2

regaurding rb20, do the math, 6 270’s on the rb20 would be equal to running 405cc injectors on a sr.
Many many people believe the rb20 to be a better engine than the rb26 once the head has been re-worked with solid lifters and new valve springs.

The greddy manifold fits fine if you slot the mounting holes just a few MM.

You forgot to mens ion rb30, and both forms of rb24. 1 being a bored and stroked version ofthe rb20 the other being a SOHC motor that nissan sold in some LHD cefiro models in the Caribbean.

RB24 consists of specially designed 82 or 83mm pistons(the rist pin is in a different location), GTR rods and crank. The block must be relieved slightly to fit the crank as the counterweights are larger. Power from these engines have exceeded 700hp and rev’s to over 11000 have been seen in some cases.

RB30 is a combination of a Holden(motor was made by nissan) Block from a early VL Comedore, and any of the rb heads. Some heads prove more difficult to swap on than others. The 1994 r32 rb25de is a direct bolt on, letting you use a stock head gasket. Rumor has it that sr 86mm pistons are a direct swap for forged pistons in the unit. Power figures for these motors are in the low 400’s on t3/4’s at around 1 bar. RIPS in New Zealand will build create motors along with any other parts for any rb.

It should be said that although the rb30 is the cheapest way of getting a 3L rb, the block is not strong enough to push 1000hp like the N1 and nur spec blocks.

Other hybrids include the RD28 with rb26 head.

3

dunno if this should be posted here or not, but, how would an RB25 respond to two smaller turbos?

4

the rb25/rb26 have the same bore/stroke, so i dont see why it wouldnt respond like a stock gtr would…but for the money to do it the gains in power would be tiny and not worth it

5

i’m not in it for max power… i like torque, lol

6

lets put it this way, the COST to make a rb25 TT along with purchase the rb25 would cost you more than an rb26 to begin with.

7

just clarifying, how can the rb25 and 26 have the same bore/stroke?

bore X stroke gives you the displacement, the numbers would have to a bit different

8

can you elaborate on how it would cost more?
not tryin to sound like a dick, but i don’t see how it would at all…
taking into consideration the fact that i need the RB25 tranny and oil pan which needs to be modded. if i used T25’s they’re not that expensive…

9

rb25/26 manifolds do not interchange, means custom exhaust manifolds, e downpipes as the manifolds wont put the turbo’s in the proper place for the gtr to use.

Intake pipe, ic pipes, ecu, intake plenum as the stock design would be just silly.

I don’t see the reason why you’re on this TT kick, you wont make much more power than a stock rb25det and you’re adding a bunch of cost. To be what? different? The head of the rb25 doesn’t flow near the same as the rb26, hydrolic lifters really suck for choises of cams, and the standard RB25 injectors can’t support 2 stock gtr turbo’s at 1 bar.

If we Add up the cost, $3500 for rb25 motorset, $800 for standard rb26 turbo’s. $1000 for front facing plenum $500-2000 for ic kit, now the next part is all custom. IF you can do the work yourself it’s just time and material. But if you can’t, $custom manifolds, $custom downpipes, $custom 1-2 turbo inlets, $custom 2-1 turbo outlets.

Since it’s not a skyline, add electric fans, driveshaft and mounts to the cost.

my bad on the bore stroke of the 25/26, but i know second hand rb26 rods and pistons bolt right into the rb25

RB25 - 2.5 L (2498 cc, bore: 86.0 mm, stroke: 71.7 mm)

RB26 - 2.6 L (2568 cc, bore: 86.0 mm, stroke: 73.7 mm)

.1L difference won’t effect spool much boys and girls.

10

ok i see where your coming from now…
but here was why i wanted to do it.

we all know a big turbo produces big power but can be very peaky… and produce no torque in comparison… and a small turbo does the oppsite, makes low end torque and falls off in higher RPM ranges.

now the reason i want low end torque and not peak power up in the high RPM range;
how many of you guys rev the piss out of your car to its limits daily driving? (this is why i don’t understand people slapping on massive turbos for the street, or Honda owners making all their power at 9k RPM). i know i don’t the highest i tend to drive the car is 6k and thats pushing it.

back to the turbo… t25s are small… and would produce more low end torque, but if you have a single t25 on an inline 6 thats silly as the turbo would not be able to handle all the flow right? but two t25s would…

as far as all the custom stuff goes… its just cost of material for me…
however… i was informed that there wasn’t much difference in the two engines i.e lifters, head
another reason for the TT set-up… i just simply like the RB26 set-up the way it is… and no it wasn’t to be different… that goal is for the 13b into an s13 or s14 :smiley:
one reason why i didn’t go rb26 is: the obvious tranny and oil pan issue, and i’ve been told that its easier to wire the RB25 for a S14 than the 26.

11

I think before you start to try and build cars and setup engines and such you should take a read through a few books… the reason for smaller engines having to rev higher to make the HP… is because they have to , there is no way they can make big hp at low RPM. The best your going to find in a 4 banger is the EJ series engines, making the bulk of it’s power at the mid range. ( ~4500rpm) 4 bangers simply don’t have the low speed torque to make the power… ( there are exceptions like the Porsche 3.0L I4 but that engine is a study in trade offs) … if you want small displacement and lower RPM torque then you’ll have to get a 2.0L V6 this has ~ 8 deg. of negative torque pulse as opposed to ~15 deg in a 4 banger. Anyway that’s just the tip of the iceberg…

Twin turbos are fine but you can’t simply take two turbos that match the flow of one single and expect it to do what you THINK it will. You need to calculate in thermal eff. frictional losses, flow losses, pressure and velocity differences between twin smaller Vs single larger… piping eff., and IC ingress…

just thought I throw that your way before you decided to play ‘car tuner’ with the UNI crowd…

12

to be specific…

Mods For RB26 DETT swap

-You have to cut the RB 25 oil pan baffles in a shape that would make room
for the Rb26 oil strainer. then the rest of this part is bolt on.

-if your RB26DETT is the early r32 version(aka if has a short snout on the crank), you might require an “oil pump drive collar” for fitment. look for one at takakaira.com this will make sure that you dont damage your oil pump specially if you plan to replace it with diff ones like HKS or N1…

-It is Better to Use a RB25DET tranny as it tends to hold up the power of the engine better than a RB25DE/SR20 tranny. RB25DET tranny will bolt on jus fine.

-get a LSD

-Buy a custom drive shaft For this installation

-Custom engine mounts are needed.

-Firewall must be dented with rubber mallet to reduce engine vibration w chassis (Must Do)

-whether you are going for a det or dett setup… you will have to custom bend your downpipe to avoid hitting the stirring column. (tight fit)

the bitch part…

-Splice the upper RB motor harness with your upper KA motor harness… then reinstall (ask a master electrician or master mechanic to look into both cars wiring diagrams and do the job) you dont want to screw on this one.

-OR-

-For $150 Us plus shipping and taxes by our beloved govt!!! Buy the EZ Mini 20 Wiring Harness. itl provide a clean look to your engine bay. www.ezwiring.com

-Buy Bosch 20/30A SPDT relays… need it to make everything work.

Automotive Relays

Common Relay Pin Configuration (Bosch-type)
Overview
Relays are widely used in electrical applications where one circuit is to be energized or turned “on” by the presence of a voltage, provided by another circuit. An example of this is when an automotive radio sends out a triggering voltage to turn on an external amplifier or activate a motorized antenna. Anywhere a switch can go in a circuit, a relay can replace it, (as long as there is a triggering voltage available to activate it).

The “switch” in a relay is more often called a solenoid. A solenoids is like a piston that pushes outward when energized with electricity. This push mechanically trips the switch in the relay, completing circuit and allowing the switched voltage output.

A relay can be triggered with an electrical pulse as small as 150 milliamps. The switched output can be as high as 30 or 40 amps.

For more info Go to: http://www.partsexpress.com/resources/relays.html

Hope this info helped aspiring RB26 swappers.

13

You could also get the Syko kit(havent used it, anyone know what it is like?). Check out the march 07 edition of SuperStreet, they have the install all layed out in there. Its hard but it does have a TT downpipe for low-mounts. They use the RB26 tranny and tell you how to modify it and why to use it.

I want one!!

-Shawn