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Possible Valve Hitting Piston Sound/issue?

mill-180

By mill-180,
in Engines & Forced Induction

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mill-180 Enthusiast

mill-180

Posted
  • Author
Posted

hey guys,

yes the sound only happens when VCT is activated, no sound with it disconnected so its definitely VCT/Cam related,

im thinking of removing the VCT completely and putting in bigger cams & adj cam gears.

Kiwi, yes they were new pistons from CP Pistons.

BoostdR, did it happen when VCT kicks in or just normal idling/driving?

mill-180 Enthusiast

mill-180

Posted
  • Author
Posted (edited)

I know it may be a long shot, but were the oil restrictors replaced (blocking off VCT, or starving the lifters with a too small one) when the head was off?

Good question moodles,

there were oil restrictors put in.

i have to confirm with the engine builder how he did it but i assumed he would've left the VVT and installed the restrictor in the rear feed & blocked the middle feed.

Ok just got off the phone with him, he blocked the middle and put the restrictor in the read feed as per the oil control thread on here.

Edited by mill-180
Dobz Experienced

Dobz

Posted
Posted

I know it may be a long shot, but were the oil restrictors replaced (blocking off VCT, or starving the lifters with a too small one) when the head was off?

I thought we were talking about an rb25 neo here? They use solid lifters.

Don Dada Mentor

Don Dada

Posted
Posted

put it on a dyno, the difference is massive.

post-42272-0-27111800-1298164261_thumb.jpg

Green / black = stock ecu 10psi

Dark blue / Red = Tuned ecu 10 psi nvcs on from 1500rpm right up ( notice how it shits itself after 5000rpm)

Orange / Light Blue = Tuned ecu 10 psi nvcs off

Its there... but i dont know if i'd refer to it as a "massive" difference :unsure:

Rolls Grand Master

Rolls

Posted
Posted (edited)

you are meant to kill the VCT after 5000 rpm or it saps top end power like shown there, I cant figure that dyno sheet out but it looks like it is making almost 75hp more at low rpm?

Edited by Rolls
Don Dada Mentor

Don Dada

Posted
Posted (edited)

Nah....

The 3 lower lines ie. black, red, and light blue is hp with their matching colored torque lines as stated above.....so for reference from the graph at 3000rpm it makes about 10hp and 17 ft-lbs more when nvcs is activated

Edited by Don Dada
Guilt-Toy Grand Master

Guilt-Toy

Posted
Posted

Take the front cover off, take the belt off and open up the VCT mechanism... check if it was put together properly and if there is any evidence of something going wrong in there.....

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