Inlet And Exhaust Camgears/n-vct, Potential Upgrade & Results

[Marco-R34GTT]

Well, being my first topic, I'm gonna try my best to not ask a "St00pid n00b" question....

I've been looking at several posts on the forum in regards to tuning the RB25DET NEO, and in a more focused sense, I'm more concern about the camshaft/camgears direction.... I can't afford a camshaft at the moment, but I can easily afford camgears and a tune... So firstly, It is well known to me that the Rb25DET NEO utilizes N-VCT, and from what I've read, many people change the exhaust cam gear only... I've also read that there may an 'adjuster' of sorts available... As per this post from another thread:

No. the RB25 has variable timing on the intake side. Bass Junky (IIRC) has made an adjuster for it though, so do a search.

Also, wanted to take maximum advantage of both aftermarket camgears AND N-VCT, I found this on wiki:

Some Nissan engines only have N-VCT on the inlet cam (such as the RB25DE/DET) while others have it on both the inlet and exhaust cams.

AND

Although there was never a factory Nissan Variable Cam System for the RB26, tuning companies such as HKS. sell aftermarket options.

So if some aftermarket (HKS) systems were available for the RB26DETT? Would similar systems be available for the RB25DET? Also, does anyone have any experiance or knowledge about these 'adjusters' and aftermarket options and whatnot? Info would be much apreciated...

A few more questions:

1: What benefit would I see from my engine (RB25DET NEO) from either both or just exhaust camgear on a stock motor?

2: What benefit would I see later on with a camshaft fitted (preferably a mild one, with a bit more lift, but good idle) working in conjunction with my camgears...

3: If I bumped up my boost to 10psi with camgears, would I see much benefit with the two changes together?

4: Is there much difference between makes for cam gears, I hear some people like HKS whilst others use OS Giken, I've read that GReddy make a more durable camgear...

Edited May 18, 2007 by Marco-R34GTT

[Marco-R34GTT]

So no one here has an answer to the application of aftermarket options/alternatives to the NVCT/Camgear arrangement??

[paulr33]

hi

i have bass junkys experiemental adjuster on my r33 rb25det

we made no power at all with any adjustments and the stock setup was the best so we set it back to that

the device is still fitted to my car, it sits behind the stock cam gear so u can adjust them without removing the cams

[jeffworld2]

rbs5det neo engines actually have vct on both cams. the rb25det in an r33 has inlet vct only, so we add an adjustable cam gear to play with the exhaust side.

Since you have a neo this may mean you wont have much use of any adjustable cam gears. if you lose the vct, it is a bit of work and you will have to pick either a) set adj cam gear for low end response or b) set adj camgear for top end. if thats fine for you, then thats great. if you try and set it for the midrange.. whats the point, it will be a bit off low AND high.

Vct is a good thing, keep it until(if) you change cams. it does the work of an adjustable cam gear, but changes while the engine revs out, like vtec yo! if you havent upped the boost yet, then cams should be at the tail end of your mod list.

HKS only made about 20 of their vcam units or whatever they were called, and they all ended up in japanese demonstrator cars such as the hks driving performer... you wont find one for sale. they are probably uber expensive if you did manage to find one.

[Marco-R34GTT]

Ah I see, I'm getting a little confused with the NEO and normal 25DET, I shoulda done more research..

Well thanks heaps, but then on that note, how will aftermarket cams work with the dual NVCT on both the exhaust and intake camgears?

[Stronzo]

rb25det neo has vct on intake cam only. so it`s possible to use exhaust cam gear, but as i have read here on this forum - there is no advantange in exh. cam gear for neo, unlike r33 rb25det.

[Marco-R34GTT]

SO if I may ask for some advice, if you were in my shoes, and so over the coarse of 12/18 months.. Your going to add 3" exhaust, FMIC, Apexi PFC, AFM, Boost increase (and later, a larger turbo), NISMO injectors and a range of other goodies... What would be better, to change one camgear, neither or both? From which set-up would I have the most to gain? In terms of camgear arrangement, or keeping the NVCT.....

[Marco-R34GTT]

Can anyone here give some feedback on how using either the stock NVCT or aftermarket camgears react when placed on either a stock motor, or with some softcore aftermarket upgrades?

[SKY 34]

gears will not help in 34s, get the Tomei type B cam. otherwise don't do anyhthing

Also you need to take into consideration that stock rb25 can take approx 400rwhp. I'm not sure the turbo size you want to chuck in.. however If you intend to have a GT30 and make 400rwhp on stock internal, do not change the cams, if you do, the power will increase further engine will stuff up even faster~~

ignore the gears until you get turbo N other stuff done, decide after everything is installed.. gear installation got nothing to do with turbo side, so doens't matter if you do everything at one go or seperately, you gonna get charged all the same...

.. but if you decide to still do it I've got brand new HKS in and ex gears for sale~~`

[ovabooster]

so cam gears dont really benifit neo's? i assume on stock and lightly modified cars thou...how about on a engine pushing 450rwkw? will they help them...with cams of course?

[Adriano]

There is a benefit to fitting a camgear to the exhaust side, only the inlet has VCT, an its the same as the r33 setup. What results are you looking for, 450rwkw is way beyond what you are looking for.

[ovabooster]

well its going into the workshop in a few months supporting a t04z... fully rebuilt with all the fruit to go with it....im trying to reduce lag as much as possible

[nikr33turb]

I drive a 33 rb25det...are cam gears a good idea?

[satanic]

Since it's getting rebuilt; just get the engine builder / workshop to block off all the VCT lines and run it without... get a set of cams and gears; and tune away. You'll see a little benefit but it is rather subjective as to whether or not it is a "gain".

The VCT on the R34 works differently to the VCT on the R33; I believe it has something to do with the electrics which makes tuning in a cam gear harder; wherever on the curve you gain, you lose out somewhere else.

Do a search of Bass Junky's threads to read up on the effectiveness of cam gears on the NEO; I think you'll find that the result was "don't do it"

Might as well put the $300-$400 towards a set of cams.

On a side note though; Tomei does suggest an alternative for the NEO; you remove NCVS and use the gear on the exhaust... I think that's the translation... someone else might be able to confirm.

[ovabooster]

thats what im trying to find out...bass junky has moderate power.....i think around the 260rwkw....Minimual gains if any...Does that neccesararly mean no gains with high power demands aswell?

[T04GTR]

no you need to pull the vct pully apart and re drill its fixings so it can be adjusted externaly. mona's engine has it. (moonie pie)

you need sonone with acess to a mill to do it. phyl ryal in windsor has done quite a few.

[T04GTR]

at the end of the day your mayby talking 5kw or so.