RB20DET vs Rb25DET

[ilkhan]

What are the differences between these two motors? Both are skyline, both I6, turbo, DOHC FI. The RB25 I know has the extra .5L of displacement, is that stroke or bore?

Dimensional differences?Power?Cost?

[Joe]

hate to be an *** buthttp://www.nissaninfiniticlub....hp?s=

its been covered many times.

[PROJECTRB240SX]

RB20DET:2.0L (1998CC)78MM BORE69.7MM STROKE8.5/1 COMPRESSION210HPROUGHLY $1500

RB25DET:2.5L(2498CC)85MM BORE71.7MM STROKE9.5/1 COMPRESSION250HPROUGHLY $3000+

THE DIMENSIONS ARE ALMOST EXACTLY THE SAME, JUST THE CROSSMEMBERS ARE A DIFFERENT DESIGN.

[wcbjr]

http://www.meggala.com

[PROJECTRB240SX]

THAT SITE HAS EVERYTHING YOU SHOULD NEED TO KNOW.

OH STOCK RB20DET CAMS ARE: 240 DEGREE DURATION110 LIFT EXH CENTERLINE115 LIFT INT CENTERLINELOBE CENTER ANGLE: 117.5LIFT: 7.8MM ON BOTH CAMSIVO: 5 DEGREESIVC: 55 DEGREESEVO: 60 DEGREESEVC: 0 DEGREESTIMING: 15 BTDC

[ilkhan]

ok

So bore AND stroke differentCost is about double for the RB25

Which is a better match for a S13 (both for straight and a little bit of squirly fun) for reletive cheap?

And RB is non-street legal everywhere in the US correct? Is the SR legal in a 240?

[PROJECTRB240SX]

NO JDM MOTOR SWAPS ARE LEGAL. RB20 IS THE CHEAPEST BUT PERFORMANCE PRODUCTS ARE LACKING AND IT HAS A HIGH REV LIMIT. THE EASIEST WAY TO MAKE MORE HORSEPOWER THAN A RB25 IS CHANGE THE RB20 PISTONS TO 82MM AND UP THE COMPRESSION TO 9.5 AND YOU GOT A HIGHER REV LIMIT, MORE HORSEPOWER, QUICKER SPOOLING TURBO, 2.2L OF PURE FUN.

[PROJECTRB240SX]

PLUS IT IS STILL LESS THAN THE TOTAL COST OF THE RB25.

YOUR LOOKING AT CLOSE TO $4500+ WHEN ITS ALL SAID AND DONE FOR AN RB25

YOU LOOKING AT $2500 - 3500 FOR A RB20 TO GET IT INSTALLED AND RUNNING PLUS ANOTHER GRAND FOR THE PISTONS AND BLOCK WORK.

[S13Sil-line]

Im hearing both sides on emitions.. A stock RB25...Will it pass emitions..in certain states?????

[JeffTN]

It will in East TN. :ylsuper

[S13Sil-line]

From what I hear, As long as they dont look under the hood, you should be fine.

[PROJECTRB240SX]

EVEN THEN MOST OF THEM WONT EVEN NOTICE.

[S13Sil-line]

I also hear that if you make them do an idle test instead of on the dyno it helps a lot more.

[PROJECTRB240SX]

JUST USE A BIGGER CAT WITH MORE HONEY-COMBS TO FILTER MORE. ACTUALLY IT RUNS LESS EMISSIONS THAN MY KA24E DOES.

[ilkhan]

any info on NV?So the power difference between RB20 and RB25 is not enough to justify the cost?

RB20DET would seem to be easier to swap also?

[PROJECTRB240SX]

HONESTLY NOT TO ME. $2000+ IS HONETSLY ALOT TO PAY FOR 40HP.

[JeffTN]

RB20DET would seem to be easier to swap also?

I imagine that the level of difficulty of installation is the same seeing as how they are physically the same size.

[PROJECTRB240SX]

WELL THEY ARE BOTH EXACTLY THE SAME TO INSTALL EXCEPT THE RB25 NEEDS A DRIVESHAFT, WIRING IS ALITTLE DIFFERENT BUT NOT THAT DIFFERENT.

[ilkhan]

so where can we find more info on doing the swap?

I imagine a clip includes 99% of what you need to do the swap. Is there anything the clip wont include that you need?

I am seeing a lot of controversy on the motor mounts. Do you need new ones ($?) or not?

Are the transmissions different?

[PROJECTRB240SX]

WHICH MOTOR DO YOU WANT?

[S13Sil-line]

Its not just 40 hp. It got more tourqe, its a newer motor and depending on what you do to it the .5 liters can help alot. Just has the downfall of a higher rev which wears out the motor quicker. There is more including bore and stroke and even a better transmission. You get what you pay for.

[PROJECTRB240SX]

IF YOU SAY SO, ITS NOT WORTH THE $2000+ DIFFERENCE IMO. BUT HEY DO WHAT YOU WILL AND BTW THE TORQUE CAN BE GAINED BY STROKING AND OVERBORING THE MOTOR.

[JeffTN]

STROKING AND OVERBORING THE MOTOR.

That can get pricey too though.

[PROJECTRB240SX]

NOT REALLY, YOU CAN GET A RB25DE CRANK AND ROD FOR LIKE $300 AND THE OVER SIZED PISTONS ARE LIKE $550, THEN THE BLOCK WORK FOR $600 YOUR STILL LESS THAN THE RB25.