VR4 intake runners.

[Jazz9]

Hello,

Without the vacum line hooked up to the solonoid for the cyclone mani, are the runners open or closed? I have mine disconnected as I misplaced the vacum setup for it when I did the engine conversion.

Thanks.

Glen

 

[CLuTZ]

Closed. IIRC its the vac that opens them

 

[rob323]

Hello,

Without the vacum line hooked up to the solonoid for the cyclone mani, are the runners open or closed?

My experiences with a prefacelift J spec are contrary to Clutz's advice and showed that when the vacuum is released from the actuator on the manifold (eg, the vacuum hose is removed from the actuator), the butterflies in the short intake runners OPEN allowing air to pass down the short intake runners to give more top end power.

With the butterflies closed, and just using the long runners, you run out of power at about 5000 - 5500 rpm.

 

[bazeng]

They are normally open (without vac)
closed with vac

 

[CLuTZ]

I thought it was the other way around- I remember to4garret having issues- or perhaps that was due to the CYCLONE not hooked up correctly, instead of not at all?

 

[GSRSOL]

They are normally open (without vac)
closed with vac

Yep, thats right - I remember we sussed it out when we were tuning the SM4 on my previous setup (using the cyclone)

 

[to4garret]

yea i got it around the wrong way, switching vacum to the soleniod closes the valves.

still need to get retuned too

 

[bazeng]

The cyclones have a little vac box which holds vac until the solenoid switches and closes it. Some guys have modified them to work with a positive pressure actuator (in the states) so it opens when boost comes on..

 

[Jazz9]

sweet, so I should just leave it disconnected? OR am I loosing lots down low?

Glen

 

[milkandoj]

The cyclones have a little vac box which holds vac until the solenoid switches and closes it. Some guys have modified them to work with a positive pressure actuator (in the states) so it opens when boost comes on..

So if you comming on boost at say 3.5K it'll open then. Not a bad idea if you flowing enough air for having them closed to be a restriction.
Anyone got a link to a thread on it on dsmtuners or dsmtalk ect?

 

[bazeng]

Use it mate, if you have the correct plumbing and ecu for it.

It does help quite a bit down low.

 

[rob323]

I agree with Baz, it does help down low, but in saying that, I leave it disconnected. The boost comes on more progressively and is more controllable when driving on loose surfaces or around corners and once you are up in the revs, you don't drop down low enough to take advantage of it anyway. My stutterbox makes up for it off the line.

 

[bazeng]

In saying that also, I'll be leaving it off on the AMG (FWD) so I can also maintain a more progressive power curve.

A good test would be to lock it with a hard wire or something.. See how it drives with the closed down low...

 

[Gooch]

runner

Hey guys,
As you know I am as technical as three toed sloth.
What are you talking about here in simple terms and will it help me chase more power for the vr?

Sorry for being so dump if someone wants to just pm me in simple terms I would appreciate it.

 

[rob323]

The prefacelift J spec vr4 has a different intake manifold to the Aus spec and facelift vr4's. It uses dual intake runners for each port. One runner is short in length (good for high rpm power) and the other is longer in length (better for low down torque development). It uses a butterfly in the short runners to close them off at low rpm which means all the air flows through the long runners. It then opens these butterflies at around 4500 rpm and the air can then flow through the short runners as well.

 

[Gooch]

The prefacelift J spec vr4 has a different intake manifold to the Aus spec and facelift vr4's. It uses dual intake runners for each port. One runner is short in length (good for high rpm power) and the other is longer in length (better for low down torque development). It uses a butterfly in the short runners to close them off at low rpm which means all the air flows through the long runners. It then opens these butterflies at around 4500 rpm and the air can then flow through the short runners as well.

Thanks Champ getting the picture now! cheers.