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Vct?

OoskylineoO

By OoskylineoO,
in Engines & Forced Induction

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OoskylineoO Experienced

OoskylineoO

Posted
Posted

Hey guys, just abit puzzled on what the VCT thing is, been searching around but havn't quite found my answer.

just wanna know what is VCT and what it does and how do you tell if you have it?,

i read sumwere all rb25de motors has VCT except an rb25de from r32, is this correct?

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Eug Grand Master

Eug

Posted
Posted

it's called NVCS, the inlet cam is advnaced 20º when the solenoid is on.

you can see a solenoid on the intake side, red plug from memory. you can also feel it kick when when the solenoid is activated.

r32 rb25de = NO NVCS = correct

put the keywords NVCS or VCT on the search engine for the entire forum, should bring up lots of hits.

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r33cruiser Grand Master

r33cruiser

Posted
Posted

here ya go:\

NVCS is the acronym for Nissan Variable cam system, it is found in the RB25DE, RB25DET and the RB25DET NEO. NVCS is not to be confused with Hondas V-TECH system which alters lift and duration high in the rev range to give higher peak power. Nissans system uses cam phasing to increase low to mid end engine torque.

Optimal valve opening and closure position for a given duration is different for every RPM and load combination, NCVS gives the engine the ability to take these factors into consideration and alters the timing accordingly. This is done using an electronic solenoid which adjusts the rotation of the cam by a maximum of 20 degrees, the solenoid is controlled by the engines ECU.

The RB25DE and RB25DET found in the R33 Nissan skyline only use the NVCS system on the intake Cam. The R34 Nissan Skyline is equipped with the NEO version of this engine and both intake and exhaust cams use the NVCS system. The RB20DET and RB26DETT do not use NVCS.

Torque curve of a VG30DETT with NVCS off and on notice the low to mid torque increase with the system turned on.

NVCS makes a considerable difference to low and mid range torque so when it comes to upgrading cams or installing cam gears it is a good idea to keep this system in place. Some manufactures (like tomei's poncam range) make cams to work with NVCS I highly recommend you consider these. As the non NEO RB25's only have NVCS on intake side an exhaust cam gear can be used as a good cheap upgrade to improve mid to high end torque.

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OoskylineoO Experienced

OoskylineoO

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o ok, that was very helpful, thanks guys, 1 more thing, ive heard alot of ppl tell me an rb25de is 140kw@flywheel and 147kw@flywheel WITH VCT / NVCS and only the rb25de from an r32 is without VCT / NVCS. So does this mean that ALL N/A r33s come equipped with VCT / NVCS? i.e, 147kW? i got a s2 33gts4 lol

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Eug Grand Master

Eug

Posted
Posted

they r33 type-s has 147kw fly, no idea where they got that number from though.

the non type-s also has nvcs, so the extra power is not due to that.

7kw is really nothing anyway. you can make or lose 7kw by running the dyno on different days, different fuel, condition of the motor, dyno settings, etc.

all r33s that came with rb25s have nvcs

some r33s came with an rb20e, they do not.

you should have nvcs in an s2 r33 gts4

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GTS4WD Grand Master

GTS4WD

Posted
Posted
o ok, that was very helpful, thanks guys, 1 more thing, ive heard alot of ppl tell me an rb25de is 140kw@flywheel and 147kw@flywheel WITH VCT / NVCS and only the rb25de from an r32 is without VCT / NVCS. So does this mean that ALL N/A r33s come equipped with VCT / NVCS? i.e, 147kW? i got a s2 33gts4 lol

But because its a GTS4 you will loose a certain percentage through the 4WD system..

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