WELL IF THAT WASN'T THE WORST STATEMENT EVER! THE RB20 IS JUST AS GOOD IF NOT BETTER THAN THE RB25. LETS SEE THE RB20 PUTS OUT 200HP TO THE GROUND STOCK AND THE RB25 IS PUTTING OUT 225-230WHP STOCK. YEAH YOU ARE GETTING .5LITERS MORE AND A STOUTER TRANSMISSION BUT WITH THE OVER $2K YOU SAVE YOU CAN MAKE YOUR RB20 INTO A RB24 AND STILL HAVE MONEY LEFT.

 

THE RB25 ADVANTAGES:
9 TO 1 COMPRESSION
85MM PISTONS
.5 LITERS MORE
RUNNING 250HP ON 7PSI OF BOOST
BIGGER TRANMISSION

THE RB25 DISADVANTAGES:
VVT
120+ ADDITIONAL LBS OVER THE RB20
LOW REV LIMIT
WEAK CAMS (NA CAMS ARE SIMILAR TO THE RB20'S)
TURBO IS WEAKER THAN THE RB20'S


THE RB20 IS JUST AS GREAT OF A CHOICE AS THE RB25.

 

Next time, just say "Yes. It will."

My questions/response to the RB disadvantages:

What's so bad about VVT unless you're going for extreme power?

Can you find a thread or something that shows the RB25 is heavier? I'm curious.

How much lower is the rev limit compared to the RB20?

I won't question the cams.

"Weaker" means ceramic turbine, right? I know with Skylines, the turbines might shatter if the car detonates.

 

VVT IS ONLY AGRESSIVE UP HIGH IN THE REV RANGE, WITH THE RB20 ITS ALWAYS AGRESSIVE.

THE RB25 IS 180LBS MORE THAN THE KA24DE SETUP AND MY RB20 WEIGHED IN AT 65LBS MORE THAN MY KA24E SETUP. SO THAT IS ROUGHLY 120+ (ACTUALLY 140 BUT I'LL GIVE BENEFIT OF THE DOUBT) LBS DIFFERENCE. MOST THIS WEIGHT IS IN THE TRANS SO ITS NOT SO DETRIMENTAL BUT IT IS STILL THERE.

WELL MY RB20DET REVS TO 8500RPM AND STILL WANTS TO GO, THE HIGHEST I'VE SEEN A RB25 GO WAS 7200. OF COURSE WITH HEAD WORK DONE TO BOTH YOU CAN SIGNIFICANTLY RAISE THESE LIMITS. THE HIGHEST I'VE HEARD OF AN RB20 GOING WAS 10200RPM WITH SOLID LIFTER CONVERSION AND AGRESSIVE HEAD WORK OUT IN JAPAN.

WEAKER MEANS LOWER BOOST TOLERANCES. ACCORDING TO A BUNCH OF PEOPLE OUT OF AUSTRAILIA AFTER 11PSI THE RB25 TURBO TENDS TO LET GO, ALTHOUGH SOME PEOPLE ARE LUCKY AND HAVE A TURBO THAT CAN HANDLE 12PSI GENERALLY THEY DON'T. THE RB20 TURBO IS KNOWN TO HOLD 13-15PSI WITHOUT MUCH PROBLEMS UNLESS ITS DRIVEN HARD AND CONSTANTLY IN AND OUT OF BOOST.

 

Thanks for the info. I always thought both engines weighed the same.

Aggressive cam advancing you mean? Isn't VVT sort of good until you hit about 400 horsepower anyway?

 

VVT IS LIKE VTECH. IT ALLOWS THE ENGINE TO RUN IN ECONOMY MODE LOWER IN THE RPM RANGE AND WHEN YOU HAMMER THE GAS IT SWITCHES CAM PROFILES AND ALLOWS FOR MORE POWER IN THE UPPER RPM RANGES. I PERSONALLY ONLY SEE A DAILY DRIVER BENEFIT TO IT.
THE RB20 HAS ONE CAM PROFILE THE WHOLE TIME THE ENGINE IS OPERATING..... THESE CAMS ARE RELATIVELY AGRESSIVE THE WHOLE RPM BAND.

VVT = VARIABLE VALVE TIMING

 

I know what VVT is in general. Is Nissan's system just a cam phasing system, or does it include lift change?

Some people don't need more than daily driving out of an engine like that, so that's why I'm asking. Not everybody is trying to squeeze the engine for every horsepower it'll give.

 

JUST PHASING.... ITS NOT THAT BIG OF A DEAL BUT FOR PERFORMANCE MINDED PEOPLE IT IS JUST ANOTHER PART TO WORK AROUND.

 

VVTC is nothing like VTec...it is a hydraulically controlled Cam advancement/retardation system that adjusts your timing in low RPM's to give you more torque and hp through your lower power band until the turbo kicks in. It cuts out at higher RPM's between 3500-5000RPMs' and allows the engine to remain in normalcy mode. Cam profiles don't change....there's no switching of anything as far as degrees or lift on the cam...it's just a sensor that aids in timing to give you the most and best power throughout your RPM band...oh yeah, CTN - your mounts is at my house. =o)

 

NIGHT RE-READ WHAT VVTC DOES.... CAM PHASING IS THE ADVANCMENT OF THE CAMS TO EXTEND THE DURATION OF THE CAM CYCLE. IT WORKS EXACTLY LIKE THE VTECH SYSTEM..... THIS IS ALSO THE REASON WHY THE RB25DET HAS A BOOST SOLENOID THAT ONLY KICKS IN AT 5500 RPM TO RAISE BOOST TO 7 PSI.

I'LL GIVE YOU A CALL TODAY CAUSE I FOUND MY BOLT PATTERN AS I FINALLY HAVE MY CAR AT MY HOUSE.

 

Actually, the RB25DET uses a two stage boost system that is 7psi from about 3000RPM's to 5500...after 5500 it kicks in to 9 psi (that's the extra kick)...it is nothing like Vtec. Vtec uses an extra cam lobe that is a lot more aggressive to open up the engine and get the extra power. I used to work for Nissan, we had to memorize crap like VVTC and CVVTC etc... All it does is alter the timing by retarding or advancing the cam for the most hp and tq per stroke in lower RPM's....when you go CVVTC it goes all the way till redline. Only the RB25DET has VVTC....RB20DET's and RB26DETT's do not.

VVTC - Variable Valve Timing Control....all it does is mess with timing.

 

RIGHT CAM PHASING... WHICH IS WHAT I SAID. ITS BASICALLY WHAT VTEC IS JUST A DIFFERENT METHOD TO THE MAYHEM.

BTW: I CALLED YOU AND LEFT A MESSAGE ON YOUR CELL.

 

Call me again...for some reason, I didn't get your call

 

OK WILL DO.

 

NO, Vtec is not only crossing over to different cam lobes, it also has butterflys controled by solenoids that are in place in the valves which at the crossover point are removed. Nissans closest thing to Vtec is VVL, not VTC