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View Full Version : Aftermarket VTC (NVCS) sprocket



dryft_s15
08-16-2009, 07:32 AM
After upgrading my S15 SR20DET valve springs to BC units, the VTC sprocket promptly started rattling. First it'd rattle on cold startup and then get quiet once VTC engages, and then it started making the knocking noise constantly.

I've since started using an S13 intake sprocket until I can find a suitable fix. There's a noticeable loss in low end torque, which has lead me to investigate the possibility of an aftermarket sprocket that won't fail with the higher spring pressures.

I'm speaking with an engineering company to possibly develop an upgraded VTC sprocket that is also adjustable! Is there an interest in this or am I alone?

seishuku
08-16-2009, 01:15 PM
I could get interested in that, since eventually I'll need to upgrade springs and cams. I'm kind of scared as to what the price might be though.

6secondS15
08-16-2009, 07:24 PM
check out these guys, they make them for the 300zx, might be able to do something for the s14/s15 sprocket.

http://bde-performance.com/vtc.htm

dryft_s15
08-16-2009, 07:36 PM
They're exactly who I'm speaking with. They're looking into options of making both adjustable and non-.

Hopefully the cost will be around the $5-600 for adjustable.

juggernaut
08-16-2009, 08:06 PM
Count me in....actually you can probably count every S14 and S15 owner in Australia in.

From my research into this it is the spring inside the sprocket that needs a greater tension to overcome the higher valve spring tension.

Mine is only rattling on the transition at the moment but will only get worse I presume.

juggernaut
08-16-2009, 08:10 PM
Haha...I just read the above link and they also agree the stock spring tension in the VCT is insufficient with aftermarket valve springs.

If it was adjustable that would be good too so can play with cam timing.

shane_B
08-18-2009, 03:35 AM
So any updates on this? I would be interested in a set down the road. Mine isn't rattling yet but I'll be throwing some 264 cams in the head and this will surely wear my VCS sprocket out.

dryft_s15
08-19-2009, 08:36 AM
I've sent in some worn sprockets for them to disassemble, analyze and re-engineer. Will keep you guys posted as I get info and possible timelines.

juggernaut
08-19-2009, 09:14 PM
Excellent - keep us posted.....any pics would be good too.

shane_B
08-21-2009, 11:45 PM
BDE told me about 6 months perhaps. Fingers crossed.

Anyone know how much truth there is to cams being "VTC friendly" or is it a bunch of marketing hype?

dryft_s15
08-22-2009, 11:07 AM
VTC cams need to be able to supply oil to the solenoid. There's a small hole in the #1 journal as well as a different bolt to go with the sprocket. Some VTC cams have both threadings for the regular sprocket and the vtc (BC, Tomei), some don't (HKS).

shane_B
03-27-2011, 08:08 PM
Any updates? I am ready to buy this now!!

Kingtal0n
03-30-2011, 06:05 PM
zombies are walking!

IMO on a street driven vehicle, that is, pump gas daily driver type deals, its better to have a lower lift camshaft, with a weaker spring. Yes you miss that last bit of flow off the top of the lift but what do you gain?

pro:
-longevity of valvetrain components

con:
-lose a bit of flow (depending on the design of the head)

its as simple as that. Ill take the longevity for my street car, thanks. #'s arnt everything. 500 horsepower, 500# seat pressure, 500 mpg, 500 dollars, none of those things means anything unless the right context is used.

chickenwings
05-14-2015, 06:28 PM
Any updates on this?
Can the spring inside the VTC just be replaced with a higher spring rate and/or coil bind?