i'm going rb20 personally. it redlines at 8 grand

rb25 is 7.5 i think.

both will perform pretty close to each other actually but the 25 will have more hp.

cool, thats what i was leaning towards too. i love high reving engines, the sound of it is just so amazing...

thanks waynehead for the response and not being an ass.

rb20... lighter and higher reving. plus i heard the rb25 swap is a killer in the pocket book.

i hear you have to get a custom driveshaft for the rb25 in a s14. I'd either go rb20 or ka-t :)

I would re think the two engines if you think that only the revs matter. I have an Rb25 in the 240 and a Skyline with the 20. I will give up the revs any day for the low and mid torque. Thats why the 20 will be replaced soon. The two motors may be close on paper (40ps) but not in real world driving. Just my 2 cents. But before this becomes a battle both RB motors a capable of what you can afford.

they are both good butbeing the same motor only one with more displaceement the 25 is better

FOund this after digging through the net....from a Nissan press release about the RB25DET engine. Funny thing is after all the searching i have down about the engine this is the first pretty hands down in your face explanation

" * RB25DET NEO Straight 6 engine
This 2.5-liter in-line 6-cylinder turbocharged engine continues Nissan*s innovative Linear Charge Concept that combines quick throttle response with good fuel economy. Furthermore, it incorporates the Nissan Valve-timing Control System (NVCS), among other advanced technologies, for a superior acceleration feel and sporty driving performance, achieving maximum power of 280 PS and higher torque output in all speed ranges."
Sounds pretty freaky to me


found more stuff here...

"RB20DET engine was superseded by the half-a-litre-bigger RB25DET. The extra capacity squeezed out of the same RB block involved increasing bore and stroke to 86.0 x 71.7mm (up from 78.0 x 69.7mm respectively). However, the RB25 also features much larger inlet runners than the RB20, a vastly improved cylinder head, a larger (ceramic turbine) turbocharger and a marginally larger air-to-air intercooler. A relatively high 9.0:1 compression ratio maintains good off-boost driveability and an airflow meter is used as the engine load sensor.

Enough gobblygook; the RB25DET is undoubtedly one of the best single turbo engines we've ever sat behind. Off-boost torque is strong, but get some load on above about 3000 rpm and she's a real rocket. Torque holds strong until close to the 7000 rpm redline - though note that our test car had been equipped with an aftermarket exhaust system. A short drive will have you believing every one of those 187kW (at 6400 rpm) and 294Nm (at 4800 rpm).

The RB25 turbo comes with either a 4-speed auto or a 5-speed manual. Our 5-speeder displayed a nice positive throw, though the clutch had been changed to an aftermarket item; this gave the most sudden transition of any clutch we've had the displeasure of operating! Despite this, the RB engine was reluctant to stall when taking off - which points to (among other things) extensive OE computer mapping."

They are both nice engines, the RB20 is the best bang for the buck I think. It's stock turbo is WAY TOO SMALL upgrade to at least a T3 from a 86-89 300ZX and you will be much happier. Overall the RB motor itself is a beast. Aside from the factory headgasket there isn't much to break.

RB25DET>>>>>>>>>>>>RB20DET

Rev's...are you guys Honda fanatics or something...
More displacement=more torque
can hold more power
Not that much heavier, but yes its heavier :rolleyes:, gut the rear seat and take out the spare to compensate.
You can get a RB25 front clip for under $3700 (www.jarcoinc.com)
Does require a custom driveshaft...oh wait McKinney Motorsports has a full mounting/driveshaft kit for this particular swap...
IMHO the 25 is so much more worth going with than the 20.
Plus the RB20 comes out of the older R32 Skyline while the RB25 is a newer, fresher motor out of the R33 (I know, that IS based on pure assumption).

for the points you listed you would be right on, but the one major thing you didnt consider is price. That is a HUGE if not most important factor for a lot of people considering a swap. Most people dont have the freedom to decide which engine they want with no regard for price. They have to make their choice based on what they can afford. Thats why the RB20 gets the "bang for the buck" award. It is much more affordable than the 25.
by the way, NICE pic in your sig, thats my kinda girl!

^speed costs money...you know that, I know that. If I was looking for the best "bang for the buck" Id be driving an SRT-4 ;)

i like the Rb20 because of it's racing heritage and i do like the sound of the RB engines reving high...RB26's are insane at high revs.

but

the RB25 is newer. it all depends in 3 years or so...no matter.

...waiting on VQ swaps to become popular...:p

this thread is comparing rb20 and rb25 not rb20 rb25 and neons

no i'm not a rev freak but i do like the sound and i love an engine that can breath in high revs. i'm still going rb20.