Which RB engine is better

[Madscientist]

Okay, I have the choice between a RB20det and a RB25det. Now I'm putting it in my 280zx which is a heavy car by todays standards. I heard the 25 has good take off but the 20 will leave it...can anyone shed some light?
The difference in price is about $2000 so I can go either way. I have no clue how much for a RB26det but I would imagine about $12000 and can't find it anywhere, so that is not a option. At least I don't think it is.
Keep in mind these are stock engines and would not be modified for a while. I'm looking at about 200-250Hp stock and enough torque to pull that car.

Help meeee.

[Dave]

a ZX was pulled by a 140-150hp engine, NA so either would be an upgrade
i would go 25, more power and stronger than the 20 if u have intentions of modding it

[wagonrunner]

Okay, I have the choice between a RB20det and a RB25det. Now I'm putting it in my 280zx which is a heavy car by todays standards. I heard the 25 has good take off but the 20 will leave it...can anyone shed some light?
The difference in price is about $2000 so I can go either way. I have no clue how much for a RB26det but I would imagine about $12000 and can't find it anywhere, so that is not a option. At least I don't think it is.
Keep in mind these are stock engines and would not be modified for a while. I'm looking at about 200-250Hp stock and enough torque to pull that car.

Help meeee.

where you heard that?
there once were 3 wagons that enjoyed abusing cefiro's and laurels with RB20DE's and RB20DET's on the highways.
a RB25DET in them was a nasty surprise. they could out accelerate it to the top of 3rd gear, but from 4th, the RB25DET would rope them in, with enough road.
stock RB's

[Madscientist]

Mine is a turbo 280 180Hp approx. How much Hp is the other engines? I "heard" that the RB20 bottom end is stronger....any pros and cons?

[Islandboy.7]

RB25 is definitly more horsepower and more CCs.
You have to know what are your intentions for the future. Are you going to leave the engine stock?
Its all about your buget and how much you know about what you are doing.

[Conrad]

Lemme guess the ppl who said that had RB20s

There's a reason why the RB25 is more expensive i.e. more:power & displacement. True there are RB20DETs out there that would cut RB25s left,right and center BUT they're modified/tuned more than their bigger counterparts. A properly tuned RB25 with proper upgrades will wash the RB20. Also the 25 has more head-room for upgrading i.e. u will be limited by the 20's displacement and stock rods before the 25.

p.s. I envy your car.

[Madscientist]

nah the people that told me that had 280zx and toyotas....soooo yeah.
I think I would buy the rb25det and mod em out in time. I'll keep the L28 and put it in another car later on.
Btw Conrad why you envy my car? you have a cefiro, you can practically turn that thing into a skyline if you wanted to.

[cacasplat3]

the rb25 has been modded countless times by gts owners who couldnt afford to get a gtr.....but still had enough cash to do some upgrades........if u look around googe u'll find lots of 400+ hp 25's, and when i found them i wasent looking for them, i was looking for rb26's.......400hp is a nice goal for a 25........
btw are u getting the neo or the normal one? i think one comes with a bigger turbo

[Conrad]

Btw Conrad why you envy my car? you have a cefiro, you can practically turn that thing into a skyline if you wanted to.

True, but it doesn't have a "Z" far less for a "ZX" after it's name.

[Madscientist]

acctually I might get the normal one but if the neo isn't that much more i'll get it. but in either case later on with change the turbo and mainfold out. What is the real difference between the 25 and the neo 25 besides the turbo?

[cacasplat3]

the neo has better performance stock.....

* RB25DET - twin-cam turbo (T28 Turbo) (245 to 250 hp and 319 N·m)
* NEO RB25DET - twin-cam turbo (206 kW (280 PS) @ 6400 rpm, 362 N·m (37.0 kgf·m) @ 3200 rpm)

RB25DE and DET engines produced from August 1993 also featured NVCS (Nissan Variable Cam System) for the intake cam. This gave the new RB25DE more power and torque at lower rpm than the previous model.

In May 1998 a NEO head was fitted, which enabled the engine to be classified as a low emission vehicle engine (LEV). The non-VCT and non-turbo was fitted to the R32 Skyline, the VCT turbo and non-turbo was fitted to R33 Skylines and the WC34 Stagea. R34 Skylines also use these engines, but they are fitted with a NEO head.

The RB25det can withstand additional boost, while still retaining the stock bottom end. figures recorded have been as high as 550hp ATW (at the wheels) using the stock bottom end. the stock head offcourse is moddified to cope with much more volumes of air.

according to this the r34's had the neo 25's and they had 280 hp........thats A LOT

[nismown3d]

RB25 > RB20

RB26's are good, just not R32 RB26's, they have bad oil pumps and water pumps. RB20's and early model RB25's also share this problem.

best RB26 is the N1 version. this motor came with a rebalanced dcrankshaft to reduce vibrations at high RPMs, and better water channels in the block. i believe they also had upgraded cams and steel wheel turbos.

if i was building an RB here is what i would do.
RB30 bottom end, with RB25 or 26 head. of course, you can't just slap it together with stock parts and expect an amazing engine, it would take a bit of money and time to put together this motor. if done right expect a great amount hp and torque.

tons of options for a good RB. for your application i would recommend an RB25. they're cheap, easy to work on, and cheap to upgrade.

[TriniGT]

The thing is you can get RB26s from the R32 that did come with longer snouted cranks, these would be the later model ones. I was unfortunate to get the older ones but I already decided to do the work and build it so scrapped it and put in the Jun crank collar, and upgraded the oil and water pumps same time. I ain't looking for big power just a nice usable powerband, with boost coming in from 2500rpm, and power somewhere around 500-600HP. Project is on hold until funds are in but I just need to order the pistons and rods and bearings. .

[cacasplat3]

nismown3d, not all the r32 RB26's had the bad oil and water pumps.....just the earlier ones, was fixed in 92 i believe.......nismo jun and hks oil pump are the pumps to get, it flows more, the n1 pump is just a higher pressure pump........
the n1 engines are sort after cuz of the stronger block and increased cooling......
the rb's all have the no.6 cylinder as the one that leans out, if u upgrade injectors, see if u could have them flow checked......have the highest flowing one at the the no.6.....

the 20 is the cheapest to mod, with the 26 as the most expensive........

TriniGT,if u dont mind me asking what turbo's u using? 2530's?

[TriniGT]

Either S15 turbos which are similar to the 2530's or a big single.

[nismown3d]

nismown3d, not all the r32 RB26's had the bad oil and water pumps.....just the earlier ones, was fixed in 92 i believe.......nismo jun and hks oil pump are the pumps to get, it flows more, the n1 pump is just a higher pressure pump........
the n1 engines are sort after cuz of the stronger block and increased cooling......
the rb's all have the no.6 cylinder as the one that leans out, if u upgrade injectors, see if u could have them flow checked......have the highest flowing one at the the no.6.....

the 20 is the cheapest to mod, with the 26 as the most expensive........

TriniGT,if u dont mind me asking what turbo's u using? 2530's?

sorry let me rephrase

all pre 1992 RB26's

[Mr. Red Sleeper]

Madscientist,
Any luck yet?

[trinidrift]

SCIENTIST i got i question for u is your intention to go sideways or just to be able to feel the power under your feet?if its sideways the 20 got more power if tuned propely it can take on the best sr around and ive been witness to rb20/25 matchups an the 25 although its got good power but its been known to fail under heavy stress