RB20DET vs RB25DET vs RB26DETT FAQ

Discuss the RB20, RB25 and RB26 series engines.
User avatar
krayton
Posts: 1090
Joined: Tue Jun 24, 2003 11:10 am
Contact:

RB20DET vs RB25DET vs RB26DETT FAQ

Postby krayton » Mon Sep 12, 2005 8:08 pm

Ok here it is. Im thinking we make a faq comparing all the engines. Now 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. damn right i am. if this turns into a flame fest ill lock it and we will never discuss this topic again -Kamin

*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

-$$$$$-$$$$$-r32 crank coller issue (kills motor)-need for rb25 tranny-hard to find r33 motors-impossible to find r34 motors-did we mention $$$$$?

RB30det hybrid

Using the higher displacement 3 L block from the RB30 engine mated to the RB25 or RB26 head can yield a very powerful engine. Here's a thread with details. zerothread?id=188136

For Specs on engines and good info also check:- http://www.meggala.com/nissanrb3css.htm



User avatar
Joe
Posts: 7275
Joined: Sun Feb 09, 2003 8:29 pm
Location: Phoenix, AZ

Re: RB20DET vs RB25DET vs RB26DETT FAQ (Kamin)

Postby Joe » Thu Sep 15, 2005 8:20 am

thread has been updated and cleaned. please feel free to keep commenting on this

i like where its going.

User avatar
Kansei240sx
Posts: 1356
Joined: Mon Nov 01, 2004 10:17 am
Car: S13 - RB25 Circuit car
71 240z - street/track day car
AE86 - Daily Drizzle/track day car
Z31t - Paper weight/street car
Contact:

Postby Kansei240sx » Tue Sep 20, 2005 5:25 am

I think you guys should differentiate the series of RB motors with in the 20 and 25


Modified by Kansei240sx at 8:31 PM 10/26/2007

User avatar
Eikon
Moderator
Posts: 11033
Joined: Sat Apr 24, 2004 3:20 am
Car: 71 240z, 93 Supra TT
Location: Lake Orion, MI
Contact:

Re: (Kansei240sx)

Postby Eikon » Tue Sep 20, 2005 6:51 pm

I beleive this info is correct: (**Edit - info reviewed and corrected by Gawdzilla)

RB20det = Top feed high impedance injectors. Stock is 270cc. Each injector will pass on about 10 ohms. Each is wired in parallel so that the total return to the ECU is ~10 ohms.

RB25det = Side feed high impedance injectors. Stock is 370cc. Each injector will pass on about 10 ohms. Each is wired in parellel so that the total signal return to the ECU is ~ 10 ohms.

RB26dett = Top feed Low impedance injectors. Stock is 440cc. Each injector will pass on about ~ 2 ohms. Each injector is wired in parallel to the ECU but in Series with a resistor. That resistor passes on about 7-8 ohms. The two signals add up to ~ 10 ohms returned to make the ECU happy.


Modified by Eikon at 7:55 AM 9/21/2005

gawdzilla
Posts: 2028
Joined: Sat Sep 18, 2004 11:51 am
Car: none

Re: (Eikon)

Postby gawdzilla » Tue Sep 20, 2005 8:38 pm

Eikon wrote:

RB26dett = Top feed Low impedance injectors. Stock is 440cc. Each injector will pass on about 1.5 to 2 ohms. All injectors are wired in series so that they add up to return ~ 10 ohms to the ECU. (6 x 1.67ohms = 10 ohms)
that explanation/calculation should be corrected...injectors are still wired in parallel, but a resistor is put in series on the +12v side of each injector. Each resistor (there are 6 in the box) is ~7 ohms, and the calculation is ~2 ohms per injector + ~7 ohms per resistor = ~9 ohms per injector pin for the ECU to ground, reducing the current going through your ECU so it doesn't fry.
Modified by gawdzilla at 12:18 AM 9/21/2005

TOPSECRT88
Posts: 1235
Joined: Sun Apr 03, 2005 10:58 am
Car: S14

Re: (gawdzilla)

Postby TOPSECRT88 » Wed Sep 21, 2005 5:52 pm

Just a quick question......

exactly how much power can the stock internals hold on an RB20?

Thanks

User avatar
masticatingcow
Posts: 2414
Joined: Fri Nov 07, 2003 8:39 am
Car: 94 Mazda FD3S

Postby masticatingcow » Tue Sep 27, 2005 8:05 am

TOPSECRT88 wrote:exactly how much power can the stock internals hold on an RB20?
zerothread?id=135005

Maybe this will help.

dsm007
Posts: 120
Joined: Sun May 08, 2005 4:07 pm
Car: 1995 nissan 240sx SE
Contact:

Re: (Eikon)

Postby dsm007 » Mon Oct 10, 2005 4:30 pm

so I guess with
Eikon wrote:I beleive this info is correct: (**Edit - info reviewed and corrected by Gawdzilla)

RB20det = Top feed high impedance injectors. Stock is 270cc. Each injector will pass on about 10 ohms. Each is wired in parallel so that the total return to the ECU is ~10 ohms.

RB25det = Side feed high impedance injectors. Stock is 370cc. Each injector will pass on about 10 ohms. Each is wired in parellel so that the total signal return to the ECU is ~ 10 ohms.

RB26dett = Top feed Low impedance injectors. Stock is 440cc. Each injector will pass on about ~ 2 ohms. Each injector is wired in parallel to the ECU but in Series with a resistor. That resistor passes on about 7-8 ohms. The two signals add up to ~ 10 ohms returned to make the ECU happy.

Modified by Eikon at 7:55 AM 9/21/2005
so I guess an RB20 is topfeed fuel rail,and it uses low impedance injectors,the injectors use a fat nose like a bosch?Or one that slims down and inserts inside on the head instead of like sitting on top of an o-ring,the DSM(eagle talon turbo's and eclipse's) 450's are LOW's and insert inside of the head,they would seem to be an easy one to find and could work.....anyone try them?

User avatar
masticatingcow
Posts: 2414
Joined: Fri Nov 07, 2003 8:39 am
Car: 94 Mazda FD3S

Re: (dsm007)

Postby masticatingcow » Mon Oct 10, 2005 4:48 pm

RB20 injectors are high impedance top feed. The 26 injectors are a better match, since you need to wire in resistors parallel to the ECU anyway... and at 440cc, they're nothing to scoff at.

User avatar
Joe
Posts: 7275
Joined: Sun Feb 09, 2003 8:29 pm
Location: Phoenix, AZ

Re: (Kansei240sx)

Postby Joe » Tue Oct 11, 2005 9:38 am

Kansei240sx wrote:I think you guys should differentiate the series of RB motors with in the 20 and 25

I have the SII motor and it doesnt not have the ceramic wheeled turbine, nor does it have VVT.
S2's have VVT, thats what the big hump on the front timing belt cover next to the CAS is.

User avatar
Swedish Mike
Posts: 1199
Joined: Tue Sep 27, 2005 9:31 pm
Car: Golf TDI, Volvo 850T5 and 200sx S13 Hatch

Postby Swedish Mike » Sat Oct 15, 2005 12:10 pm

How about the crank shafts, can you use RB26 crank in a 20 or 25?Only asking about lenght and bearing size, not stroke.This engines got pretty much the same block right? (Accept bore.)

User avatar
eh?
Posts: 1781
Joined: Sat Jan 24, 2004 2:26 pm

Re: (Swedish Mike)

Postby eh? » Sat Oct 15, 2005 1:24 pm

Swedish Mike wrote:How about the crank shafts, can you use RB26 crank in a 20 or 25?Only asking about lenght and bearing size, not stroke.This engines got pretty much the same block right? (Accept bore.)
Yes you can use rb26 cranks in both. No they're not the same block. RB26 supposedly had larger or stronger webbings.

User avatar
Swedish Mike
Posts: 1199
Joined: Tue Sep 27, 2005 9:31 pm
Car: Golf TDI, Volvo 850T5 and 200sx S13 Hatch

Re: (eh?)

Postby Swedish Mike » Sat Oct 15, 2005 1:37 pm

eh? wrote:Yes you can use rb26 cranks in both. No they're not the same block. RB26 supposedly had larger or stronger webbings.
Thanks!

Ah, ok. But the RB20 and 25 is probably strong as hell, even the small CA18 block or the aluminum SR20 can handle a lot with forged internals.The crank thing is good, I found forged ones to the 26 but not the others.

Do you know if I can use 26 cams in the 25 head? Diameter and lenght?

/Mike

User avatar
Nismochick240
Posts: 2022
Joined: Wed Sep 07, 2005 9:00 am
Car: 95 240sx- BONE STOCK.. for now
Contact:

Postby Nismochick240 » Mon Dec 05, 2005 12:32 pm

ok i have a question. I am starting to think that ka-t is not the way i want to go. Its about the same amount of money for an rb25 but you just dont get that SKYLINE sound! hehe!

So anyways, on this custom driveshaft, where can you purchase one at? I was looking at the "where did you get yours" thread and saw 300plus picked a rb25 clip from jarcoinc.com and it came with a stock driveshaft. Can I use that one or would it have to modified in someway? thanks guys!

User avatar
Joe
Posts: 7275
Joined: Sun Feb 09, 2003 8:29 pm
Location: Phoenix, AZ

Re: (Nismochick240)

Postby Joe » Mon Dec 05, 2005 12:46 pm

Nismochick240 wrote:ok i have a question. I am starting to think that ka-t is not the way i want to go. Its about the same amount of money for an rb25 but you just dont get that SKYLINE sound! hehe!

So anyways, on this custom driveshaft, where can you purchase one at? I was looking at the "where did you get yours" thread and saw 300plus picked a rb25 clip from jarcoinc.com and it came with a stock driveshaft. Can I use that one or would it have to modified in someway? thanks guys!
it needs to be custom. you use the yoke (part that goes into the transmission) from the skyline/300zx and the rest needs to be shortened/made.

call a local driveshaft shop for estimates, they are in the phone book.

BTW that could have been easily found by searching if your seriously considering a RB swap the search function needs to be your best friend because its not anything like a KAT or SR.

User avatar
Nismochick240
Posts: 2022
Joined: Wed Sep 07, 2005 9:00 am
Car: 95 240sx- BONE STOCK.. for now
Contact:

Postby Nismochick240 » Mon Dec 05, 2005 12:57 pm

yea i'm searching right now for stuff on the RB. hmmm...My dad owns a machine shop. I wonder if he could shorten it. I'll search a lil bit more before i ask any questions

User avatar
Wulfgang
Posts: 908
Joined: Tue Oct 28, 2003 5:41 pm

Postby Wulfgang » Tue Dec 06, 2005 8:34 am

Hmmm... maybe we should also get a sticky (or just another thread) where people post FACTS about the weight change. I did not weigh my S14 before or after the swap, but here's my fact:

My floor jack now has MORE clearance (about 1/8") when I push it under the front lip. This is after swapping to RB20, including everything but cruise (kept stock A/C, battery location and size, SMIC, etc). In addition, I now have two PermaCool High Performance fans in front of the radiator, which probably weigh about 5 lbs more than the stock fan setup (they have steel frames and heavy motors). I also have the N1 Dual exhaust, which would seem to be heavier than stock, but I did not weigh it.

At any rate, the springs don't lie. There is no arguing that the RB20 is heavier than the KA24DE, but the center of gravity must have shifted backwards a bit to make the front lip come up. Perhaps that is the extra weight of the exhaust. No matter... the balance has shifted toward the rear, and that ain't bad.

[EDIT] In case I am not being clear, my basically stock RB20 swap shifted the balance favorably toward the rear wheels.

User avatar
Joe
Posts: 7275
Joined: Sun Feb 09, 2003 8:29 pm
Location: Phoenix, AZ

Re: (Wulfgang)

Postby Joe » Tue Dec 06, 2005 8:43 am

im all about getting the weight balance bull**** taken care of

only problem is only a very select few people have weighed their cars PROPERLEY before and after the swap. and only 1 to my knowledge has corner weighed the vehicle. i have access to corner scales at work but have never gotten around to doing my car. maybe i should..

User avatar
Shocker
Posts: 2082
Joined: Sun Aug 01, 2004 2:40 pm
Car: 89 240sxHB rb26/30

Re: (Kamin)

Postby Shocker » Tue Dec 06, 2005 9:56 am

I was considering this idea as well, i have a local Lafarge around here.. "mining company" they have trucking scales all good to within 10 lbs, i might bring my daily up there sometime, fully wet, and put her on the scale, then take the project once thats done.. see the difference.

User avatar
Flicktitty
Posts: 4252
Joined: Tue Sep 21, 2004 11:56 am
Car: 1989 Nissan 240sx XE - 2JZ-GTE Swap
2008 Lexus IS350
2010 Toyota Prius
Contact:

Postby Flicktitty » Fri Jan 06, 2006 10:08 am

thanks!

andrewmp6
Posts: 72
Joined: Sat Sep 24, 2005 9:42 pm

Postby andrewmp6 » Sat Jan 07, 2006 4:46 am

2 kinda dumb questions will the rb26 main bearings fit the rb25 and will a intercooler kit for a r33 fit a s13 or will i have to make it fit

mugengsr
Posts: 76
Joined: Tue Mar 08, 2005 1:46 am
Car: SKYLINE GTS-T TYPE-M
Contact:

Re: (andrewmp6)

Postby mugengsr » Mon Feb 06, 2006 9:04 am

main bearing in all three rb`s are the same

David_NISMO
Posts: 44
Joined: Sun Apr 02, 2006 11:27 pm
Car: RB26DETT powered S13

Back on Topic

Postby David_NISMO » Sun Apr 02, 2006 11:38 pm

The RB25 crank is not FULLY counter balanced. The RB26 is.

My favorite part about the rb26 is that the entire motor will support over 425RWHP before any modifications need to be made. This includes, injectors, mafs, turbos, and ofcourse all internals.it also has internal throttle bodies which create better engine responseStock bottom end has been taken to over 1000hp.

RB25DET is 9:1 Compression, better low end torqueRB26DETT is 8.5:1 Compression, bring on the boost baby!!

All RB motors are basically Factory Blueprinted. I love seeing the look on people's faces when I tell them that.

User avatar
Joe
Posts: 7275
Joined: Sun Feb 09, 2003 8:29 pm
Location: Phoenix, AZ

Re: Back on Topic (David_NISMO)

Postby Joe » Mon Apr 03, 2006 5:39 am

its individual throttle bodies, not internal.

sure the engine can see 425whp without much modification but the 10,000$ pricetag for a 26 swap you could fully build a 20 or 25 and see 600whp.

all engines are "blueprinted" thats the list of specifications found in any service manual that is used when the engine is assembled.

David_NISMO
Posts: 44
Joined: Sun Apr 02, 2006 11:27 pm
Car: RB26DETT powered S13

Re: Back on Topic (Kamin)

Postby David_NISMO » Mon Apr 03, 2006 5:50 am

I'm totally borrowing this from Race Bread

Yes, different engines have different size bearings. Instead of a one-size-fits-all-hope-it-works system like some low budget engine manufacturers we won’t mention here (Chevrolet, Ford, etc.), Most Japanese manufactured engines run on exact clearances (blueprint). Because the machines work engine after engine after engine, tolerances vary. To make up for this, there are different bearings, pistons, etc. to choose from. For example: Standard main bearing thickness for grade 1 for the SR20 is 1.977-1.980mm and grade 6 is 1.995-1.998mm (There is only one size for undersize bearings). That’s a 0.021mm or 0.0008” difference between the thinnest and thickest shell for a total of 0.042mm or 0.0016” total difference per journal. This system works awesome in two respects; it ensures that every engine leaving the factory has spot-on clearances (Yes, this means that the RB26 is, for the most part, “blueprinted” in stock form), and it gives high performance engine builders a range of clearance options. The “old” way for “the other” engines is to mike bearing after bearing to try and find a thicker or thinner one to meet your needs.

all of this is from Matt... the skyline pimp... i take no credit i just was lucky enough to get the information

That's all I know. Thanks for the correction on the ITB, I was a bit tired.

User avatar
Joe
Posts: 7275
Joined: Sun Feb 09, 2003 8:29 pm
Location: Phoenix, AZ

Re: Back on Topic (David_NISMO)

Postby Joe » Mon Apr 03, 2006 6:03 am

dude all engine manufacturers use a specific set of clearances for bearings and wall clearances and runout and thrust and everyother thing you measure in an engine when assembling. thats what blueprinting is.

David_NISMO
Posts: 44
Joined: Sun Apr 02, 2006 11:27 pm
Car: RB26DETT powered S13

Postby David_NISMO » Mon Apr 03, 2006 6:51 am

o.k. so what's the big deal with people having their motor's blueprinted.

Does that mean that a lot of rebuilds, people used to just slap in some bearings and call it good? And those who get theirs "blueprinted" just means they took the extra time to get their tolerances as exact as they can? Note to Moderator:Thanks, and feel free to delete these last few posts as they are definately off topic

User avatar
Joe
Posts: 7275
Joined: Sun Feb 09, 2003 8:29 pm
Location: Phoenix, AZ

Re: (David_NISMO)

Postby Joe » Mon Apr 03, 2006 6:58 am

if anyone just slaps bearings in an engine they are building, they should not be building an engine. measuring for exact tolerances is a necessity when building an engine and every good engine builder on the planet knows this.

all blueprinting means is its built within the specs as the manufacturer reccomended in the service manual.

David_NISMO
Posts: 44
Joined: Sun Apr 02, 2006 11:27 pm
Car: RB26DETT powered S13

Re: (Kamin)

Postby David_NISMO » Mon Apr 03, 2006 7:02 am

okay, thanks

User avatar
Black on Gold
Posts: 6542
Joined: Wed Oct 12, 2005 5:20 pm
Location: Winterthur, Switzerland
Contact:

Re: RB20DET vs RB25DET vs RB26DETT FAQ (TOPSECRT88)

Postby Black on Gold » Mon Jun 12, 2006 7:48 am

TOPSECRT88 wrote:Awesome sticky man. This should eliminate the 100,000 RB20 v RB25 v RB26 swap topics. We shoulda thought of this earlier.
Word. Thats my dilema right now


Return to “RB20DET / RB25DET / RB26DETT Forum”