[Wurx]

After reading on the forum, my understanding is that the MILVS mod only provides increased valve lift at 80% and greater gas pedal position. Is this true? Even after you get the BPC MILVS tune?

[rjahl]

Originally Posted by Wurx

It has been stated that the MILVS mod only provides increased valve lift at 80% open and greater throttle position. Is this true even after you get the BPC MILVS tune? or does the tune make it effective at all throttle positions?

With the N52 valve lift = throttle.

The DME uses the valve lift to control engine load while the throttle is more of a back up device.

[W37V]

Originally Posted by Wurx

It has been stated that the MILVS mod only provides increased valve lift at 80% open and greater throttle position. Is this true even after you get the BPC MILVS tune? or does the tune make it effective at all throttle positions?

I feel the difference regardless how much throttle I give. So, from my personal experience, your statement is false.

[hassmaschine]

The tune doesn't really have any affect on how the MILVS physically operate. You just won't make a lot more power without re calibrating for the extra lift - the engine thinks maximum lift is 9.7mm but it's really closer to 11mm.

As far as "no effect until 80%" that's not really accurate and a misinterpretation of what Marty originally posted. The goal of MILVS was to change the rocker ratio curve to gain lift at full throttle but not affect low throttle or closed throttle positions (because that would negatively affect idle, emissions and driveability).

They are machined so the change at low lift positions is minimal (basically 0 at closed throttle), and increases as you get closer to full lift. So there is a much bigger difference in lift at 90% eccentric shaft position than there is at 20%. It's not an "on/off at 80%" thing at all.

[Wurx]

Originally Posted by hassmaschine

The tune doesn't really have any affect on how the MILVS physically operate. You just won't make a lot more power without re calibrating for the extra lift - the engine thinks maximum lift is 9.7mm but it's really closer to 11mm.

As far as "no effect until 80%" that's not really accurate and a misinterpretation of what Marty originally posted. The goal of MILVS was to change the rocker ratio curve to gain lift at full throttle but not affect low throttle or closed throttle positions (because that would negatively affect idle, emissions and driveability).

They are machined so the change at low lift positions is minimal (basically 0 at closed throttle), and increases as you get closer to full lift. So there is a much bigger difference in lift at 90% eccentric shaft position than there is at 20%. It's not an "on/off at 80%" thing at all.

This is the information I was looking for. Thank you! This is a really good explanation, and I understand it now. I have edited my initial post based on replies to make it more clear for future readers.

[Taskmaster]

What they all said.

[bbnks2]

I see the effect of the MILV mod as pre-loading the valve spring. Can anyone explain how the supports are machined such that the valve springs are only affected during high cam angles? Genuinely looking to learn more about this. My last post on this was backwards as I was assuming that the actual seat was being machined down and not the point where the support bolts down.

Lift should only be occurring when the cam gets into the elliptical portion of the lobe to cause lift. If the preload of MILVS was so great as to cause lift during the other 80% of the cams rotation then you would have little to no compression.

[W37V]

Did you check out the original thread?

https://www.e90post.com/forums/showthread.php?t=1329840

[weehe126]

Originally Posted by bbnks2

I see the effect of the MILV mod as pre-loading the valve spring. Can anyone explain how the supports are machined such that the valve springs are only affected during high cam angles? Genuinely looking to learn more about this. My last post on this was backwards as I was assuming that the actual seat was being machined down and not the point where the support bolts down.

Lift should only be occurring when the cam gets into the elliptical portion of the lobe to cause lift. If the preload of MILVS was so great as to cause lift during the other 80% of the cams rotation then you would have little to no compression.

The "MILVs" support is machined down at an angle. Basically nothing is removed where the eccentric shaft is at minimum lift, keeping the stock idle. About 1mm is removed on the max lift side of the support to create the 1mm extra lift. I don't think the "only above 80% throttle" is accurate. You can think of it as your valve lift range from throttle input went from 0mm-10mm to 0mm-11mm.