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[archiewood]

Hi all,

First post - I'm putting an X30XE in my Cavalier and there's a number of useful bits and bobs around here, so thanks for that.

I'm using the C25XE management which can't control the switch-over valves (I haven't got the resonance switch-over valve anyway), so I was wondering if it's better to lock the intake switch-over valve in the open or closed position? If open is better I might just remove it altogether and blank off the hole. Cheers.

[hotel21]

Sorry Bud, you have an overabundance of switchover valves for me...

Could you tie down what you are actually asking, please? 

[archiewood]

The plenum switch-over valve, mounted to the back of the plenum and controlled by a vacuum solenoid?

I can't operate this valve, so is it better for it to be permanently open or closed?

[hotel21]

Rear multiram.....  Bettrer to get it working.  Check the vacuum connections and ensure no leaks.   

[Kevin Wood]

On the whole, the valves give better low down torque when closed (the two intake runners are separated) and better top-end power when open. Hence, they are normally switched at RPM thresholds by the Omega ECU.

The valve in the intake ducting opens at 3400 RPM and the valve in the plenum opens at 4100 RPM but is also open at idle otherwise an imbalance between the two throttle intakes would cause a lumpy idle.

Operation is described here:

http://www.omegaowners.com/forum/YaBB.pl?num=1153840176

I would say, if you have the Omega intake setup, the best plan would be to get an Omega ECU and get them working properly.

Kevin

[archiewood]

Ah yes, rear multiram. Can't get it working I'm afraid - replacing the engine loom is a step too far for me

It's going to be permanently open or closed. I guess I could leave the mechanism in for now and experiment when the engine's fitted.

[Kevin Wood]

In that case, I would go for open, personally.

Kevin

[archiewood]

OK, thanks for the help!

[Marks DTM Calib]

Yes open or remove the flap assembly and make a blanking plate.

This will sacrifice low down torque but would ensure max bhp at the top end.