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RB20 vs RB25

5.1K views 24 replies 13 participants last post by  DLSracing  
#1 ·
Hi guys

guys I must choice between this 2 engine the RB20DET or RB25DET

what do you think

my goal is low 11s at the drag track so I want the shortes way to my goal

I do alot of search befor I post here and found alot of info. but tel now I can not choice between them.

how many HP can product with those to engine RB20,RB25 with the full bolts on (FMIC, 3" ex, air filter, 12 psi) and what is the 1/4 mile time on those.

I know that the RB20 is

* 214hp (silver top)
* smoother than the RB25
* higher rev. than RB25
* lighter than RB25
* easy to swap in S13 than RB25 (as I know)

and about the RB25 is

*250hp
*more displacment by 0.5L


so any one have more info about those engine plz info me

my main Quz is:

1- which engine is easy to swap in S13 ?

2- which one has more problems on it ?

3- if the Bolts on (FMIC, EBC, 3" EX, air filter) in both engine what is the diff. in the HP will be between it ( is it good power to spend those extra $ on the RB25)


My car is 89 200sx Euro. ver. came stock with CA18DET with ABS and LSD

I want the car to the drag race not alot intrested in drift.

so PLZ guys any post will help me :thumbsup

thanks
 
#2 ·
stupid question...
RB26DETT hands down. if thats completely out of the question then the RB25 will be what you want.

i dont know if you could see 11's on an RB20 without alot of work.

I know that the RB20 is

* 214hp (silver top)
* smoother than the RB25
* higher rev. than RB25
* lighter than RB25
* easy to swap in S13 than RB25 (as I know)
RB20 will give max of 200RWHP once its in and running.
it is no smoother than the RB25
it does rev higher, but that doesnt mean anything
it's not any lighter than the RB25 to make a difference
not any easier than the RB25 (RB25 requires a few more parts, but labor is the same)

I would not get an RB20. the engines are old, have lots of miles, and have probably been sitting for along time. If you want 2.0 liter get an SR20DET

Also, I have swapped, an RB20, an SR20, and an RB25. the RBs are about the same amount of work (easy if you have the right tools)
and the SR20 is very easy and i like it more than the RB20. (doesnt sound as nice, but the power feels nicer.)

i could see an RB25 with those bolt ons hitting 300RWHP (get a light weight driveshaft), just remember that the stock turbos on RBs shouldn't be run past 12PSI if you want to keep them.
 
#3 · (Edited)
theXfiend said:
stupid question...
RB26DETT hands down. if thats completely out of the question then the RB25 will be what you want.
I say RB20 or RB25 coz I can not buy a RB26DETT


is the RB20 tranny same as RB25 tranny ?

I need to know the HP numbers for the 2 engine with the bolts on

I know that the RB25 will product more HP than the RB20. is this more HP good for the more $ in the price
what I mean here, is this diff. in the HP number (40hp @flywheel stock) good for this 500$-1000$ diff. in the price.

thanks
 
#4 ·
........................

in before lock.

You should know better than to post such a question :nono. Use the search button if you want to know about Rb20 vs RB25.

20 revs better than the 25
25 bigger than the 20
25 has more horse power than the 20
20 is cheaper than the 25
20 can use the same drive shaft as the KA
20 is lighter than the 25 because of the tranny

How big is your bank? if you can afford a 25 then get one. If not get a 20 if you want. Note "you want" because thats what it's all about. It's about what you want to put into your car. You can hit 11 sec with a SR20,RB20,RB25. If you don't like to have to rev a motor high to make power get the 25. You will have more HP out the box just becareful how you tune that high comp motor or BOOM! lol j/k

Let the RB20 vs RB25 wars start

"RB20 is old"
"it's only a 2.0"
:rolleyes:
 
#5 ·
Go get a RB30ET motor and throw on an RB25 head that should blow all those other RB motors out of the water.

__________________________________________
1994 GMC Sonoma V6
Custom exhaust, K&N Intake, Accel Performance Distrb Cap/Rotor, JBA Racing Plug wires, Bosch Plat 2 plugs, Castrol syntec w/ K&N oil filter, 2000 xtreme rims, PIAA extreme white lights.

1992 Nissan 240sx SE Coupe 100% STOCK. New Project
Mobil 1 Synthetic w/ K&N oil filter, NGK Iridium IX Plugs
 
#6 ·
O.K guys

I know that any think I want to do is back to me.

but I want to see your opinion and your experience guys

now I want one think plz

for any one do the swap RB20 or RB25 or have any info about it

I want to know your HP/TQ number and your mod. in the RB20 or RB25 and if you run it in the 1/4 mile track

thanks guys
 
#7 ·
theXfiend said:
I would not get an RB20. the engines are old, have lots of miles, and have probably been sitting for along time. If you want 2.0 liter get an SR20DET
it all depends on where you get them from, most people i've seen get bad clips buy them because they are the cheapest clips they can find.if you buy from a respectable dealer, you should be fine.
 
#8 ·
theXfiend said:
stupid question...
I would not get an RB20. the engines are old, have lots of miles, and have probably been sitting for along time. If you want 2.0 liter get an SR20DET
now this is the most retarded statement that i have heard in a LONG time.
basicaly you are telling me that my 93 engine is older than the 91 (sr) engine in my friends car.
or that mileage has alot to do with engine power.
or that fact that an sr20 is also a 2l.
but yet ive seen lots of ppl pay 3.5k-4k for an sr that looks like it was used for a boat anchor.
I personaly have a rb20 from a 93 with 100k mi on the clock (yes thats 100k mi) and it has put down more power than most stock sr's do with the same mods as i had done.
it put down 180whp and 175ft/lbs torque consistantly on a mustang dyno and also had a SMOOTH power and torque curve.
point here is DONT BASH THE MOTORS, even if you dont like them.
 
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#9 ·
If you want to run 11's you need a 25 a t3/t4 maybe .70 trim Stand alone engine management (power FC, E manage) 550 or bigger injectors, after market cooling, and a few other things but lets face it with that money you could most definitly have an RB26.. but getting 11's in that is no challenge, bolt ons should do it..

Decide which platform you wan to go with then do it, I didnt go with a 25 becasue I wanted to run low 1/4 mile times (sure thats a perk) but its just the motor I wanted, you gotta figure out what YOU want,, every person on this forum is gonna have a different opinion about which is better, and how to get what to run what times or have whatever HP.
 
#10 ·
RB20
Cheaper to buy
No driveshaft needed.
Cheaper to upgrade (Injectors are cheap) And you can hack the stock ECU to make power.
It has a boost friendly CR.
Thats my 2 cents
 
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#13 ·
O.k guys

I do some cal. and found that:

my 200sx weight 2777lb (1260kg) (with me and a CA18DET engine) so I need a 400 HP at the flywheel and with a 15% loss of tranny it will 340 whp

so the goal is 340 whp

so what is need to reach 340whp with

RB20DET
RB25DET
SR20DET

I think there is some guys get 350whp in SR20 so I can do it with the RB20DET

and about the prices
in my place we have alot of RB20 in alot of Datsun so there is alot of it and a parts for it

I can get:

RB20DET (with ECU,engine wiring,MAF,tranny) for 800$

RB25DET (with ECU,engine wiring,MAF,tranny) for 1350$

the two engine is without labor so the RB25 hard ro install so more $ for labor
----------------------

so if I install the RB20 I will save a 550$(with out cal. the labor $) and I can mod. my RB with this 550$ and get the diff. in the HP betwee the 20 & 25

--------------

+ I can found the engine it self 400$ for the RB20DET and 800$ for the RB25DET ( maby I will break the engine :heyhey )

and we have a good used parts for the RB20DET in bahrain



sorry for long post :thumbsup


thanks for help guys
 
#16 ·
mohnissan said:
but it do not have the power of RB or SR

and we do not have a parts ( aftermarket or OEM ) for it in my place.
with the money it would cost you to put a new motor in you could buy a big turbo, metal head gasket, cams, etc and with good tuning 350+ at the wheels is very possible.
 
#17 ·
the problem with the CA18 is

it is 1.8L so it dose not have a good TQ

and the emportant think is that here in Bahrain we do not have any parts for the CA18 not the racing parts and also the OEM parts

me ex-car was also a 200sx put I sawp a SR20 on it it was very good and if I have a lot of mony I will go for it .

but about the RB20 there is a ton of parts for it(OEM or racing ... used or new) and with very good price.
 
#21 ·
Any of these motors will run 11's, you can have a 600 hp rb26, and still run 13's if you're a shitty driver. It all depends on your driving. I've seen a S13 with 375hp run 11's, awesome driver. Cheapest route, is the RB20 swap, t3/t4 turbo same as most use on the KA .63 AR 50 trim (bolts up to stock manifold), reconditioned dsm 450cc injectors, 3 inch exhaust, fuel management and tuning will get you 400 hp, and if you can drive you can see 11's.

Thats my thoughts.

E
 
#22 ·
driftjunke said:
Any of these motors will run 11's, you can have a 600 hp rb26, and still run 13's if you're a shitty driver. It all depends on your driving. I've seen a S13 with 375hp run 11's, awesome driver. Cheapest route, is the RB20 swap, t3/t4 turbo same as most use on the KA .63 AR 50 trim (bolts up to stock manifold), reconditioned dsm 450cc injectors, 3 inch exhaust, fuel management and tuning will get you 400 hp, and if you can drive you can see 11's.

Thats my thoughts.

E

O.K man I choice the RB20DET and I am in the progress to install it.

thanks
 
#23 ·
I chose the RB20 because I will be using my car for Auto-X and drifting. If you are not using it for those reasons a 25 would be the better choice. Both engines will achieve the necessary power to get into 11's, but the 25 will do it more reliably. The transmission has been proven to 7-800hp, while the 20 trans, which has the same guts as the KA and SR trans, is about 450-500hp. The 25 will also get you more torque, which always helps when dragging. If it only costs you 500-1000 more for the RB25, you will probably end up spending less going that route because of the extra displacement. Also, you have to take into account the extra wieght of the 25's trans, so you'll have to make a little more power for the same 1/4 mile times.

Hope that helps

PS. -driftjunke, that's the biggest FMIC I've ever seen, what are the dimensions?
 
#24 ·
Well I guess I can throw in some of my thoughts of the 2 motors now having both of them. Yes I have the 25 in my 240 and the 20 is in the skyline. Having the 25 first (even though its in a lighter car) I am just not satisfied with the 20. That is why I wont have it long. Along with most of the japanese people wth the 32. The 20 is a great motor like all Rb series motors but it just does not have the low end grunt. Yes they rev higher and the power is up higher. Race cars no problem, but slower tracks and better yet the street the low end is needed. Mohnissan you stated you were happier with the SR over the Ca. Same thing here with the 20 and 25, and again with the 25 and 26. Dont get me wrong all of the CA, SR, RB series motors are awsome and all pleanty capable. With that all said my choice of the two would be hands down the 25(actually the 26 if I wanted a straight drag car) due to extra grunt. Like I said I know have a 25 and 20 and this is my opinion of the two motors. Now my opinion will soon change when I put the 26 in, I'm sure of it.
 
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