VCT rattle in SR's

[NZSilvia]

Hey could someone please discuss with me in detail the VCT rattle in my S14 as i'd like to know a bit more about it and what it effects etc

[hanzbrady]

Originally Posted by NZSilvia

Hey could someone please discuss with me in detail the VCT rattle in my S14 as i'd like to know a bit more about it and what it effects etc

VCT was Nissan's attempt to give the SR more low-end torque, however; if you plan on making any more power than stock you should look into deleting that headache.

[jr_ss]

Originally Posted by hanzbrady

VCT was Nissan's attempt to give the SR more low-end torque, however; if you plan on making any more power than stock you should look into deleting that headache.

I think he wants to know why it rattles, but I could be wrong.

Second, do not delete the VTC. There is absolutely no reason to remove it. As stated, it increases low-end torque in the later SR motors. If you purchase cams that retain it, you'll have a much flatter and broader trq curve. I can garauntee that if you remove the VTC your car will seem slower than with it intact. I kept VTC on a top mount build and had 315ftlbs of trq on 12psi pretty low in the rpm range which is impressive for a 2l.

With that said, general reasons for the VTC rattle; old age, poor oil pressure and/or increased spring tension(stiffer springs). Usually it starts with a slight rattle at start up.

[pacotaco345]

Originally Posted by hanzbrady

VCT was Nissan's attempt to give the SR more low-end torque, however; if you plan on making any more power than stock you should look into deleting that headache.

Originally Posted by jr_ss

Second, do not delete the VTC. There is absolutely no reason to remove it.

Florida failing then redeeming itself in back to back posts. The VTC sprocket rattles when it gets old, you can pick up a new one for a million dollars or look around to find a used one that will last a couple years hopefully. It does make a huge difference though, so don't get rid of it.

[jr_ss]

Originally Posted by pacotaco345

Florida failing then redeeming itself in back to back posts. The VTC sprocket rattles when it gets old, you can pick up a new one for a million dollars or look around to find a used one that will last a couple years hopefully. It does make a huge difference though, so don't get rid of it.

I think there is a lot of misconceptions surrounding the VTC. Most people don't know what it does or how it works. A lot of times they are too cheap to replace the VTC gear and their ultimate fix is to delete it, which opens another can of worms.

[hanzbrady]

Originally Posted by jr_ss

I think there is a lot of misconceptions surrounding the VTC. Most people don't know what it does or how it works. A lot of times they are too cheap to replace the VTC gear and their ultimate fix is to delete it, which opens another can of worms.

Usually we convert the heads to run aggressive s13 cams or go VVL, my opinion may be biased though, dude to most of our builds being suited for racing where less moving parts is ideal.

[zombiewolf513]

The oil pressure causes the internals of the gear to advance the cam timing. I'm not 100%, but I believe this happens when oil pressure builds on one side of that ID/OD gear (in the center of the bottom pic), then that gear moves front-to-back like a piston actuator, and the helical nature of the teeth rotate the central gear (with the keyway for the cam) relative to the sprocket gear to advance the camshaft timing.

[zombiewolf513]

The rattle noise comes from when that ID/OD gear gets worn.

[jr_ss]

Originally Posted by hanzbrady

Usually we convert the heads to run aggressive s13 cams or go VVL, my opinion may be biased though, dude to most of our builds being suited for racing where less moving parts is ideal.

That logic is flawed because there are far more moving parts in a VVL head.

There's no reason to run a Low-Port head with anything other than the VTC intact. Adding VTC compliant cams will really wake that setup up. If you want a better flowing head or all out performance setup, a High-Port out flows the low-port and/or a VVL will out flow them all, as I'm sure you're aware.

[Tom N]

Anyone who says get rid of the vct on a S14/15 sr20det has never really messed with a car that has one plain and simple.

[zombiewolf513]

Originally Posted by Tom N

Anyone who says get rid of the vct on a S14/15 sr20det has never really messed with a car that has one plain and simple.

I've raced a buddy with an identical setup minus vct in my car. If you can have it- have it. it really makes a big difference

[boost]

here's a video on how to repair it. i don't know anyone who has done this personally. i think most just buy the whole thing. guy in the comments said just replace the spring which seems to be different from whats shown in the video. i guess its a common failure on maximas also

https://www.youtube.com/watch?v=YIxzvKpnriA

[Juan@Fontananissan]

There are three things that will cause the rattle,

1 Worn VCT Gear
2 Poor Oil Flow to head
3 Stiffer valve springs without enough oil pressure @ the head.

the first one is an easy fix but a couple hundred bucks. ( http://nissanraceshop.com/product/s1...-vtc-sprocket/)

the second two aren't as easy, sometimes the VCT solenoid will get gummed up so people will replace it and have some luck. it's a $95 part and takes 15 minutes to change. (50/50 shot really) other times it's poor maintenance that has clogged the orifices of the cylinder head and you don't have enough oil flow to the camshaft solenoid / gear. in that case hot tanking & cleaning is the best way to solve your issue.

[Kingtal0n]

I know its crazy but, when I enable VTC on my HKS 272 my engine actually becomes MORE lopey, and LESS drivable. I had to disable it completely for the best drivability and economy. And yes, I am sure it works, I put a set of OEM cams into the engine and it worked exactly like it was supposed to and improved performance. I also changed the VTC gear to a late model S15 unit just for the heck of it.

Not sure why this is, but there it is. It was pretty shocking but I am 100% when that intake cam moves forward 20*, I lose all kinds of drivability.
When I get a dyno time I will push it forward and just make the double pass to compare (the real way to set vtc on/off point is run the engine with, then without, overlay the two and you will see a very obvious spot to switch it off) for all I know, it makes more torque.