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Plenum swapping between ecotec models - Need help with sensors/valves

VSSECO

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Hey guys. OK so as everyone knows, the early ecotec plenum/inlet manifolds are different to the later VT VX VY models... SO, whats required for me to install a complete VT manilfold and plenum on my VS??? If i'm using the complete upper and lower manifold then will the PCV valve be functional? What about the other sensors. I cant remember what the new one one the VT model is called.

Who's done the swap?
 

cander24

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Yep i've done it. I sourced a brand new vx manifold and plenum which I match ported and polished and installed on my vs.
The vt manifold will not have the provision for a coolant temp sender (the small brass one that works your temp gauge) which on the vs is threaded into it just under the thermostat. So on this same spot on the vt manifold you are going to have to drill a hole and tap a thread for it. It is a tapered thread, not parallel, so the further you screw the sender into it the tighter it gets. I'm almost certain the thread is 1/8NPT. The thread for the coolant temp sensor (the larger one also into the thermostat housing) is the same between models so just swap the sensor over from your vs.
The plenum is also different. On the back side of the throttle body flange there will be a hole that is roughly 15mm diameter from memory that on the vt-vy models is hooked up to the EGR valve system. This does not exist on the vs models so you will need to fill the hole somehow. I welded mine, but if you dont have the gear to do this you could also cut a thread in the hole, and then thread in a bolt with thread sealant to blank it off.
The PCV valve setup is slightly different, but does function just the same. The minor difference being in the point at which the crankcase hydrocarbon gases are fed back into the plenum. On the vs plenum this hole is in the back lefthand corner, whereas on the vt-vy plenum it is located on the right hand side in the centre of the plenum. You will see on the top machined face of the manifold that there is a little channel for the gasses to pass through to allow this slight difference. All this change does is makes re-combustion of these gases a little easier as they are drawn into the manifold ports with the air intake through the throttlebody. That probably sounds a little confusing but you will understand once you compare the two.
The valley/manifold gaskets are the same on all ecotec's, but the manifold to plenum, and throttlebody to plenum gaskets are different on the vs to the vt-vy as the vs uses o-rings on these, whereas the vt-vy uses a metal gasket on the manifold to plenum joint and a paper gasket on the throttlebody to plenum joint.
While your at it i'd also recommend using the vt fuel rails as they are solid steel piping with no flex-joins like on the vs which have been known to leak.
Hope that helps ;)
 

VSSECO

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Thanks heaps, thats exactly what I was after! All makes sense to me! ...and EGR is what I was trying to remember, I figured i'd have to weld it up. Totally didn't think about the temp sensor tho, thanks for the heads up.

Only thing i'm not sure on now is the mace insulator... The PCV hole will be in the wrong spot wont it??? I dont remember ever having to specify vs or vt to mace when I bought it???
 

p_schrapel

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hey guys im just wondering is there any differences between the vs to vy manifolds as in performance wise. i know EGR is different.
 

cander24

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Thanks heaps, thats exactly what I was after! All makes sense to me! ...and EGR is what I was trying to remember, I figured i'd have to weld it up. Totally didn't think about the temp sensor tho, thanks for the heads up.

Only thing i'm not sure on now is the mace insulator... The PCV hole will be in the wrong spot wont it??? I dont remember ever having to specify vs or vt to mace when I bought it???
Your insulator from Mace will be fine and will work on all ecotec's. The location of the PCV valve in the inlet manifold remains the same, its just a small channel on the underside of the plenum that re-routes where in the chamber the gases are released ;)
 

cander24

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hey guys im just wondering is there any differences between the vs to vy manifolds as in performance wise. i know EGR is different.
Unfortunately theres not really any performance benefits in the upgrade. The manifolds flow the same but I have heard that the later plenums are slightly better in terms of distribution when running boost.
 

cander24

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No worries, glad to help. I just found this pic too so thought i'd post it up for you. The red arrow indicates the PCV valve channel that I was talking about which does not exist on the vs manifold. The hole in the vs plenum lines up directly above the PCV valve/spring setup in the manifold, whereas on the vt-vy it lines up directly above the end of this channel. Hope this is helpful.
 

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VSSECO

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Ah, I've got ya. Thanks for the pic, that clears up some things. So, I've got myself a spare manifold now but I'm actually confused as to what model it has been removed from...

As you can see in the pics, my manifold has:
- Holes for both temp sensors
- O ring gaskets between plenum/manifold and plenum/throttle body
- PCV on the side of the plenum, not re-directed to the plenum neck

All these things would indicate that the manifold is obviously a VS manifold, right, BUT if you look at the pic of the plenum neck you will see that it has an EGR hole in it. That confused me a lot!

So, is it possible that it has come from something like a VS ute (which is a VS model but built years later when EGR was being used)??? IF SO... do you think that the VT fuel injectors with better spray pattern were used? (The injectors from it have 4 holes in a sqare arrangement)

Doesn't matter really but I'm just curious. I'm just gonna have to weld up the EGR hole... at least I dont have to drill and tap temp sensor holes.
 

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