Q"s about VVT RB25DET??? WHAT IS WHAT??

[85URK]

hi pplz, just wondering about a few things, i bought a timing belt off ebay,to fit an RB25DET engine, now i was talking to a guy 2day and he was telling me that his coil packs were stuuffed and that he needed to get RB25DET VVT (VAIRIABLE VALVE TIMING) coil packs off the series 2 for his car. that got me thinking that if my car has a vvt engine in it, does that affect the type of timing belt you buy for the 2 motors (VVT & Non VVT) and how do you check for VVT on your motor?? ive heard if your timing cover has a round plastic lump on the fron tof it, it is VVT??? can any1 confirm this. thanx for all your help. 85URK

[blind_elk]

The coil packs (which initiate the spark) have no relationship to VVT (which controls when air/fuel or exhaust gasses enter/leave the combustion chamber). The need to get S2 packs is probably because the S2 packs have an in-built igniter, whereas the S1 packs require a separate igniter module.

VVT changes the relationship of the camshaft to the cam pulley, so the same belt should operate the cam pulleys, irrespective of the presence or not of VVT. As well as the "power bulge" in the cam cover, VVT can also be identified by a small solenoid mounted at the front of the head, immediately forward of the inlet manifold, near the 2 temp sensors.

[85URK]

thanks blind_elk. your a champ. very helpful indeed.

[smok74]

The RB25Det with variable timing is also known as the 'NEO' RB25det. It originally came out in the R34 GTT and it has a few more kw's compared to the R33 version. The Neo was also available with a tipronic auto as well as a 6 speed manual. The Neo did not come out in the R33 so if you find one then it's been converted with a R34 unit. The actual physical

differences in the two motors is inside the head as there are slight differences in the water/oil gallaries where the head meets the block.

Some people doing the RB25det head on a RB30 block conversion will know about this as it's the normal non-Neo head that is used, the Neo RB25 head does not work with the RB30 block as some of the above mentioned holes does not line up.

[siksII]

The RB25Det with variable timing is also known as the 'NEO' RB25det. It originally came out in the R34 GTT and it has a few more kw's compared to the R33 version. The Neo was also available with a tipronic auto as well as a 6 speed manual. The Neo did not come out in the R33 so if you find one then it's been converted with a R34 unit. The actual physical  

differences in the two motors is inside the head as there are slight differences in the water/oil gallaries where the head meets the block.  

    Some people doing the RB25det head on a RB30 block conversion will know about this as it's the normal non-Neo head that is used, the Neo RB25 head does not work with the RB30 block as some of the above mentioned holes does not line up.

incorrect, the new engine was only in the r34, but variable valve timing was on the r33 rb25det as well and that engine is NOT reffered to as the new engine. its only on the inlet side on an rb25det in r33s.

in relation to your question, the coil packs are different on series one and two skylines but the difference is not related to vvt or no vvt so dont worry.

[Maxx]

http://www.nissan.co.jp/COMPASS/TECH/SIX/frame3.htm

is VVT = NVCS ?

[MonstaS4]

R33 RB25 has NVCS (VCT)- the inlet camshaft is advanced 20 degrees with respect to the cam gear when the solenoid is on.

R34 RB25 Neo - not sure. It has VVL (variable valve lift) doesn't it?

[RB30-POWER]

The R33 VCT is either on/off for the advance like MonstaS4 said.

On the R34 Neo it is variable the amount of advance applied to the cam, not just on/off the full 20deg advance.

Atleast thats my understanding.

It doesn't do anything with the valves like a Honda VTEC does, it just advances/retards the inlet camshaft, much like an adjustable cam gear would do, except it isnt fixed. If that makes sense.

[PHaT MR30]

yeh i am just figureing out how to connect this up to my microtech, something like it switches on at 1800rpm, and switches off at 3500rpm... get my tuner to sort that out though

[BADHAB|T]

Firstly, its called VVL on Nissans. VVT is on Toyotas

VVL was introduced in the R33 Series 2, I think. May be on the Series 1 too....??

Its a wonderful thing to have, I feel it after 5000 rpm. It gives huge kick to the point it feels like a second small turbo kicking in. Its by no means slow before 5000 rpm either

Here is a pic of my engine bay, the 'lump' is just to the left of the sticker on the cam cover

[AlphA]

Very interesting..

So all R33 GTS-T's series TWO have this?

[2BNVS]

mine is a gts-t type m 95 model and according to that pic with the lump on the left of the cam cover, then mine has this too???...so confusing what came with what lol... there was a thread that i couldnt find again that stated some gts-t type m came with the series 2 engine, how can i tell the difference by lookin at it?

ben...

[race_snooze]

mine is not a series 2 but appears to have this, but i was sure that 33 didnt have vvl

[AlphA]

Im very confused aswell..

I might have a look into this hey..

[maximajim]

RB30 is right.

It's NEO VVT not VVL, the SR20VE has VVL tech. VVL= Variable valve lift ie: VTEC. NEO VVT is constantly variable timing aka CVTC on newer nissans.

[Sydneykid]

Hi guys, all R33's I have seen have VVT, both GTS and GTST, 2 door and 4 door. Even Stageas have VVT. It varies the inlet valve timing only, does nothing to the lift or the exhaust timing or lift. The only RB25DE I have seen without VVT was in the later R32's. The R33 RB25DET has simple "on" or "off" VVT, it is "off" up to around 4,500 rpm then "on" from there to rev limit. The "off" mostly is for emmisions and fuel economy, although it does help slightly with torque. The "onj" is for power, although it doesn help slightly with emmisions and fuel economy..

The R34 RB25DET (Neo, as it is sometimes called) has infiniitely variable VVT, the (later generation/smarter) ECU moves the inlet camshaft timing around depending on the load conditions (not just RPM). The Neo versions of the RB25DET are good for 206 kw, around 20 more than the R33 versions. They also have solid camshaft followers (R32 and R33 RB25's have hydraulic).

My 20 cents worth:cheers:

[AlphA]

Nice.. Thanks man.

[MonstaS4]

Sydneykid, i'm not calling you a liar, but i'm pretty sure the R33 NVCS is OFF from 0 - 1050rpm, then ON until 4500rpm, then OFF again until redline. This is how it is setup on my RB30DET and I've noticed a distinct lack in power up to 4500rpm when the NVCS plug falls off the solenoid! (due to lost metal retaining clip).

[Alf]

mine is a gts-t type m 95 model and according to that pic with the lump on the left of the cam cover, then mine has this too???...so confusing what came with what lol... there was a thread that i couldnt find again that stated some gts-t type m came with the series 2 engine, how can i tell the difference by lookin at it?

Another way to spot variable valve timing without removing anything.

The solenoid sticks out of the head below the fuel pres. reg.

You can identify a s2 motor by its build date.

The underside of the coil cover (this is 10/94 =s1)

The front of the head, with the timing gear removed (again 10/94 = s1)

Hope this helps

[2BNVS]

oh k thats heaps for that...

cheers...ben.