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Removing Vct Solenoid And What The Result Will Be?

CEF11E

By CEF11E,
in Engines & Forced Induction

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CEF11E Veteran

CEF11E

Posted
Posted

If anyone can help me out with this little pickle...

I am really trying to get my head around VCT and really need to know exactly how it works. I understand the mechanics of it just not what state it is in at what RPM.

please take a good look at the diagrams below. this is my understanding on how it works.

1.jpg

In the above picture you can see there is no oil going to the cam wheel. I pulled out the VCT solenoid and applied power to it and have observed that the holes furthest in are BLOCKED OFF when power is applied making it a normally open solenoid.

2-1.jpg

In this picture you can see that oil IS going to the cam wheel. this happens when there is no power applied to the solenoid.

What I need to know is, What will happen if i remove the solenoid alltogether. will the cam be advanced 20 degrees all the time?

please only comment if you are sure.

there is a problem with the original oil supply I have tapped and i would prefer to block it off, remove the VCT solenoid and supply oil into the hole it screws into if possible. It took me a while to draw this :worship: so please take a moment to think about it and help me out if you could!

thanks

Simon-S14 Grand Master

Simon-S14

Posted
Posted

what do you want to achieve with this?

I run my rb25det with the vct disabled. By disabled i mean its not wired up. I have no blocked it as such.

Now i believe that the VCT only operates in a range of 1400 rpm to around 4000 ish rpm, then switches back off. So if you have it blocked off and have it so its activated all the time you will find you may have a stronger midrange and a lesser top end.

nice diagrams anyway :P

CEF11E Veteran

CEF11E

Posted
  • Author
Posted

hehe, yeah.. MS paint FTW...

I want to be able to remove the solenoid and use the hole to supply oil to the front cam journal. the head is on an RB30 bottom end so the block does not have an oil gallery to supply the head :dry:

if I remove the solenoid VCT will always be on from what I gather but i really need someone to confirm this. I want it always off.

Warpspeed Experienced

Warpspeed

Posted
Posted

The way the VCT works is that the cam is retarded below 1400 rpm to remove all valve overlap. This has nothing to do with performance, it just enables the engine to pass statutory idle emissions.

From 1400 to around 4000-4700 the cam is advanced to improve low end torque by allowing an earlier inlet valve closing point. The higher rpm 4000-4700 is different between the DE and DET engines, and different year models.

Above 4000-4700 the cam is retarded to produce later inlet valve closing and improve higher rpm breathing.

All this is just to try to recover what is lost by using such a small inlet cam. If you use a larger cam, say 254 or 262 duration, and you don't care about emissions, it will work better everywhere without the VCT.

The GTR is able to pass emissions without VCT because it has the six throttle body induction. If VCT added anything to performance, the GTR would have it !!!

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