Exige Exhaust on Evora

[Doug Ashley]

On 20/04/2023 at 11:32, elandri said:

It's noted above that the valve is normally open (i.e. with no vacuum connection it's loud). So, presumably, relies on vacuum to close it (quiet)?

My understanding is that vacuum is greatest on a closed throttle and reduces as the throttle is opened and manifold depression becomes nearer to atmospheric.

So, I'm struggling to understand how a solenoid valve can do anything other than invoke full "loud mode" or how a restrictor would delay the opening of the valve. I'd have though it would hasten it?

That’s correct, the valve defaults to open with no vacuum present.

The solenoid has two settings, one which allows the vacuum to pass down to the exhaust, or one which blocks the vacuum (ignoring for a second the vacuum itself is 'nothingness' 😆). The initial feed from the airbox provides enough of a vacuum for normal operation of the valve, I don’t think you need to worry about throttle position etc.

Not sure if that answers your question, and I'm sure there are others far more qualified to comment than me.

[elandri]

Thanks guys,

I think I'll get it put on, tee it into the airbox flap vac and see if I think I need extra control.

I have a pal who is an MSA scrutineer and has a his very own calibrated noise meter. That should at least let me know if I'm OK for the static noise tests. Will have to wait and see on the drive by front.    

Will keep you posted.

[grog]

I'm about to dona similar thing and put a valved silencer on a LE car.

If I understand correctly.

Tee into the vacuum line controlling airbox valve. Use this to actuate the exhaust valve.

I'm not sure what the flow restrictor / car jet is for? What is this needed to do?

Under this control the exhaust automatically opens up at about 3k rpm?

If the control side is taken care of, can a larini valved silencer be run at higher RPM in quiet mode?

[thealastair34]

Without the carb jet restriction then the valve will always be open regardless of the sport mode or not

You can play around with the size of the restriction to move the RPM when the valve opens, i just bought a set of carb jets for a scooter from ebay was £5 or something then tried larger or smaller ones, the sizes are stamped on the jets