[1_v00d00child]

Let's talk about valve controllers.

Specifically the technical reason why the valves do not open 100% stock. Is it for emissions, is it for back pressure on the turbos?

Before I install a valve controller I want to know the downside to getting rid of the reason this was engineered into the function of the valve position.

If I understand correctly: the SST controller will revert back to OEM function.

But what is the OEMs design intention?

[mike@x-ph.com]

I guess it’s meant to keep the sound quiet in comfort mode and prevent it from getting too loud in sport. same reason BMW exhausts are so muffled, with four cats, 2 resonators, and a huge muffler.

If they wanted to, they could easily make the car louder while still passing emissions but the majority of BMW customers dont want a louder car and are not into tuning or upgrades

[tom @ eas]

Originally Posted by 1_v00d00child

Let's talk about valve controllers.

Specifically the technical reason why the valves do not open 100% stock. Is it for emissions, is it for back pressure on the turbos?

Before I install a valve controller I want to know the downside to getting rid of the reason this was engineered into the function of the valve position.

If I understand correctly: the SST controller will revert back to OEM function.

But what is the OEMs design intention?

Here's the BMW white papers on S58 electronic valve control:

[Mikesbimmer]

Originally Posted by tom @ eas

Here's the BMW white papers on S58 electronic valve control:

Great read! Seems open position has no detrimental performance impact but if stuck in closed position at high engine speeds it could have detrimental performance. Wide open for the win!

[tom @ eas]

Originally Posted by fanofbmwe46

Great read! Seems open position has no detrimental performance impact but if stuck in closed position at high engine speeds it could have detrimental performance. Wide open for the win!

100%. A proper Valve Controller like the Awron CanFlap follows those same procedures and has integrated safety measures in place to protect this from ever happening.

[Info@mad-us.com]

Simple. They do it to utilize the muffler to achieve the sound and dB levels they want.

Our valve controller lets you switch back to OEM with the click of a button, so you’re not losing any features just gaining full control over the valve position, whether that be 100%, 75%, 50%, 25%, or 0%.

https://mad-us.com/mad-bmw-supra-min...ve-controller/

[sycd]

Originally Posted by tom @ eas

Here's the BMW white papers on S58 electronic valve control:

Interesting that according to that document, if the sound button is pressed, the valves will be closed for a longer time. Seems backward to me.

[sycd]

In stock form, do we know the maximum valve open percentage for each mode (comfort/sport/sport+)? That document from BMW is very vague.

[mike@x-ph.com]

Originally Posted by sycd

In stock form, do we know the maximum valve open percentage for each mode (comfort/sport/sport+)? That document from BMW is very vague.

Sport+ will open 100% at full RPM but it wont be open all the way at low or mid RPM, thats why the controller makes a difference in the sound even without any other exhaust upgrade