Vct Alternative For 25/30

[CEF11E]

When I built my 25/30 I came up with the idea of taking out the VCT solenoid and replacing the solenoid with a tapped fitting. then feeding that fitting oil from a t peice just before the pressure sender.

this will mean VCT is always on. but supply the needed oil to the front cam journal.

all the parts needed cost me under $100 including the braided stainless line.

I have now been using this setup for over 6 months and it works perfectly. you would only use this setup if you were not going to retain vct.

hope this helps someone

[Al]

Correct me if i'm wrong:

Wouldn't removing the VCT completely and fitting a non vct cam and cam gear achieve the same results? With the ability to "dial" the cam in with the adjustable cam gear.

Most people upgrade cams during this build, as most purchase bigger turbos, etc, and the cams produce great results for very reasonable costs. So if you didn't want VCT, you'll be better off removing it completely and using an adjustable cam gear, just like the GTR setup.

[CEF11E]

that would be fine, but you still need to supply oil to the front cam jornal somehow. so you would still need to drill and tap a supply for it. doing it the way i mentioned prevents this

[Guilt-Toy]

i know of a few vl's running around with 25det heads without any VCT oil lines etc etc

[SECURITY]

sorry guys, this might be a nub question but cant you put a T piece between the VCT solenoid and the head so you can retain VCT by doing it your way Nic?

[bluegts]

i know of a few vl's running around with 25det heads without any VCT oil lines etc etc

How? I have an RB30 bottom and 25det head sitting in the garage... I want the cheapest and easiest way of 'joining' them. lol. I only want about 250kw, its the torque I'm after. I don't wanna do any drilling/tapping though.

Cheers, Jack

[CEF11E]

sorry guys, this might be a nub question but cant you put a T piece between the VCT solenoid and the head so you can retain VCT by doing it your way Nic?

unfortunately not the solenoid sits deep in the head and has a seal. it acts like a gate between 2 galleries. to taking it out and replacing it with a feed line removes this gate.

if you want to retain VCT you would need to tap into the vct gallery on the front of the head.

[CEF11E]

How? I have an RB30 bottom and 25det head sitting in the garage... I want the cheapest and easiest way of 'joining' them. lol. I only want about 250kw, its the torque I'm after. I don't wanna do any drilling/tapping though.

Cheers, Jack

it really only costs about $100 to do it my way. if you do not supply oil to the front cam journal you risk scoring the cam and even causing it to seize or produce resistance putting strain on your timing belt.

this could cause you to skip a tooth or even snap a belt or a cam, all of witch would kill your engine. it can be done but i would not do it

Cheers!

[bluegts]

lol well I won't do it that way. When you said 'your way' I thought you meant you've done it, then you said you wouldn't do it haha.

Any other suggestions? Or comments on the above method?

Thanks, jack

[Craved]

his = using the hole for the VCT solenoid to feed the oil (no drilling of the head)

way he wont do = not feed any oil at all by skipping the drill and tap or not using his method

His method is great if you dont run std cams OR if you dont run cams that are designed for VCT motors (IE. poncams are designed to retain VCT)

[fletch rb30]

You drill and tap the plug just under the inlet cam, and pull it out with a slide hammer. its about 40mm long, but will prob snap in half when you pull it out. you can re-drill the bit left in the head and pull that out too. i would suggest drilling right through with say a 2mm drill bit first off.

This plug blocks the lifter gallery from the front cam journal.

Then you get a bit of brass machined to the correct diameter so you can tap it in for a pretty tight fit. get a 1.5mm hole machined into the end of it about 30mm deep.

Tap this plug into the hole until its flush.

drill down from the cam journal oil hole into the brass until you hit the center of the plug.

using this method you can run the vvt without the external oil feed, or you can run a non vvt inlet cam. just leave the solenoid in place but unplugged.

you only need the 1.5mm restriction down the centre of the plug so there is not too much oil flow dumping through the vvt solenoid from the lifter gallery when the solenoid is not energised. This method means you also dont have to weld up the oil gallery at the front of the head near the water jacket as it will be blocked off

you should have all the lifters out when you do this and throughly clean the head before re-fitting it.

hope this helps.

[Mr Jollwah]

sounds great fletch, finally vct with out ext oil feed.

Got any pics?

[bluegts]

it really only costs about $100 to do it my way. if you do not supply oil to the front cam journal you risk scoring the cam and even causing it to seize or produce resistance putting strain on your timing belt.

this could cause you to skip a tooth or even snap a belt or a cam, all of witch would kill your engine. it can be done but i would not do it

Cheers!

The cam journal is fed from both sides by a small hole anyway. One hole from the oil gallery. It wouldn't really matter if you didn't feed the vct with oil at all.

Jack

[The Ant]

unfortunately not the solenoid sits deep in the head and has a seal. it acts like a gate between 2 galleries. to taking it out and replacing it with a feed line removes this gate.

if you want to retain VCT you would need to tap into the vct gallery on the front of the head.

Does this solenoid need oil Pressure?

If your trying to keep VCT and did this and the solenoid needs oil pressure to operate this gate, hence this is why its screwed into an oil gallery, isnt this solenoid at a dead end of the oil gallery so running another flowing oil passage off it as in tapping into it and running another oil line before the solenoid, this would relieve the oil pressure not making the solenoid work the VCT or is there enough constant pressure to operate the solenoid?

I have never worked on a RB25 motor...even though I own 2 RB25 engines

[fletch rb30]

on the vvt motors there is a constant oil feed at the front which feeds the vvt only. it has a 1.5mm restriction in it at the top of the block and it runs straight up into the front cam journal. the front cam journal has 2 holes, one is a return back into the top of the head by the valve springs and stuff. on the way, the return goes through the solenoid. the vvt is engaged by the solenoid energising and blocking the return. this creates pressure in the front cam journal. you can see on the cams they have a groove on them, this goes right to the pulley on the front and when it gets oil pressure it moves the vanes inside the pulley and the camshaft position relative to the pulley changes. when the solenoid opens, the pressure drops off and the pulley goes back to normal timing.

clear as mud?? i think it makes sense

At first i was just going to run a rb20 cam, cut the solenoid in half at the pulg end and weld it up so it was always sticking out and blocking the return, then i would have engine oil pressure at the front cam journal and it would be lubricated.

[psi]

Ok, I have my head in bits (needs help poor thing!),

so, while its all apart, I'm going to do this mod. Its exactly what i was already looking at doing. Great minds ehh?

I will track the oil feeds and stuff and activate the solinoid just to check all is well before its all put back together.

I will take photo's along the way.. The best part is, with out the external feed in sight, who would ever know what they are looking at? hehe

Thanks for the tips..

[SECURITY]

can we get a pic of this mod connected?

[raZ1911]

I thought VCT was ment to turn on and off?

But this will keep it allways on?

Or am i totally wrong? lol

[psi]

doing this mod, the VCT will work as normal..

The oil gallery that feeds the cam buckets will now also supply oil to the VCT. This removes the need for an external oil feed, and also will reduce the amount of oil going to the top end! so I will not be replacing any of the oil restrictors.

by doing this, it appears that the the solinoid may actually work backwards due to the reverse flow of the oil through it, however this will be easy fixed the ecu switching when it gets tuned..

I will be taking my head to get the orginal oil feed port welded today, and a surface grind. Will post pics soon of the bits I have done and plan to change.

that help?

[fletch rb30]

doing this mod, the VCT will work as normal..

The oil gallery that feeds the cam buckets will now also supply oil to the VCT. This removes the need for an external oil feed, and also will reduce the amount of oil going to the top end! so I will not be replacing any of the oil restrictors.

Correct, remember to drill a 1.5mm hole in the new bung you put into the gallery, or you will lose a lot of oil through the vvt feed past the cam, past the solenoid and into the head.

by doing this, it appears that the the solinoid may actually work backwards due to the reverse flow of the oil through it, however this will be easy fixed the ecu switching when it gets tuned..

The oil will flow past the vvt solenoid the same way as factory. the solenoid works by blocking the return oil AFTER it has been to the front cam journal. When it is energized, it blocks the return, the front cam journal is pressurised and this activates the vvt.