550/F50 exhaust system

I was reading a technical book I have about the 550 Maranello, and in particular the part explaining the exhaust system.

It states the following:

"...a system with variable back pressure (similar to that on the F50) and bypass valves situated on the rear silencers."

It goes on to mention the activation of the valves is based on engine speed and throttle valve.

Basically I just want some more info on exactly how it works (and its advantages) and what the similarities are with the system used on the F50.

(I know this could go in the Supercar section but I think a couple of the most qualified people to answer are here)

 

Same as several others too.

It's a noise/emission thing.

For slow running and low noise the exhaust bypass is shut, making the silencer do more work, and making the catalytic converters warm up faster, which gives cleaner emissions sooner.

The little bit of extra back pressure also help throttle response and "pick up" from low speeds.

If you demand power (speed/throttle) the bypass opens and more noise lets rip and back pressure drops off.

It's just a big steel butterfly operated by vacuum. You can see it easily up the tail pipes of 550, and even easier on F50.

Some fast bikes use it too.

On a 550, I reckon I can tell if the bypass is working or not, from the drivers seat. It's common for people to lock them open.... for the noise. You lose a little pick up without doubt.

 

Does the exhaust flap work off the same solenoid control as the intake manifold?

 

No.

 

what exactly determines when it opens, is it just at a set RPM level?

Is the bypass either open or closed, or is there levels in between?

 

I could have sworn it opens earlier, but the manual says to test it opens whenever full throttle is applied and over 5000 rpm.

I think it opens whenever full throttle is applied and rpm over ~3000rpm.

It's either open or closed.

 

Yes the test is like only 64km'h~ soo it passes with flying colours. The 360 and 430 have it as well no? Also the new Aston Martins and I heard some BMW's and other manu's use it now. As well as well as some aftermarket exhaust companies.

 

you're talking about the 550 here?

 

YSS's capristo on his F430 is astonishing in the difference in sound. in 'quiet' mode it's barely louder than a taxi, even when putting the boot in a little, but with the bypass on it's like an F1.