MILV mod

[JCip91]

Has anyone taken a look at the MILV mod? I didn't see a dyno for the n55 but they did post some for the n52 and s55 and it has shown some great potential. I imagine the n55 will be somewhere between those. It has to do will milling down the eccentric shaft supports to force the valvetronic stuff to 100% open at WOT.

[gtjosh]

After you posted this i did some research and I am looking forward to the results. The person that first posted about this in the F30 forum said that some shops and tuners have these in their hands and we should see results soon.

here is the post I found

http://f30.bimmerpost.com/forums/sho....php?t=1451059

[JCip91]

Yeah it looks pretty awesome. I'll be following it as much as I can. I saw a dyno for a s55 and it gained a few horses. I would assume the car needs to be tuned for the mod as well.

[iminhell1]

Looks like that Mike guy is just trying to market something he doesn't full understand. Some of his math is dead wrong.

I would say it's something interesting to watch develop. But It sounds like a bunch of work/cost for minuscule potential gains.

[JCip91]

Yeah I'm not a math guy. Just something to follow and see what happens.

[bbnks2]

Originally Posted by iminhell1

Looks like that Mike guy is just trying to market something he doesn't full understand. Some of his math is dead wrong.

I would say it's something interesting to watch develop. But It sounds like a bunch of work/cost for minuscule potential gains.

I agree. I was going to post the same sentiment, but I decided not to waste my breath since people only want to hear positive things. If this picks up top-end power on an N55 it is likely to be from the tuning itself and not necessarily from increased valve lift.

There were a lot of questions that went unanswered in the original thread. For instance, when discussing the issue that BPC supposedly ran into on the turbo N52, there was an entire portion of the discussion Marty neglected to take into account in his assessment and calculations of effective valve spring rate. Increased boost means increased cylinder pressure acting on the face of the valve which would have an equalizing effect against the increased boost pressure acting on the back side of the valve when CLOSING. For this reason, the general consensus is that increasing boost pressure is inconsequential to the required valve spring rate needed to prevent valve float. How valve overlap is tuned complicates this matter even further. The only issue I can see with increased boost is pushing the valve open when it is closed and seated... that is not valve float. Machining down the supports will reduce the pre-load of the valve spring, so this issue would become more likely as less force would be required to overcome the pre-load force on the spring and un-seat the valve.

Also, the before and after dyno that they presented of a turbo N52 shows that boost was UP 1psi in the "after" dyno (red line). Increasing valve lift should've resulted in LESS boost at the same WGDC if the MILVs truly reduced intake valve restriction... All I learn from the posted results is that they tuned the car for more boost/wgdc and that's how they picked up power... Or, this mod is actually reducing valve lift and that's why we see the big increase in low end torque and a bit more boost.

I am looking at the pictures and diagrams of how valvetronic works and I can't seem to wrap my head around how machining down the support would have the effects that are being claimed... Seems to me that all machining down the support will do is reduce the amount of return force of the valve spring and reduce valve lift (decreases the effectiveness of the intermediate lever). Or, did I miss something and these new supports are thicker? IF the supports are thicker, then I got this all wrong and you can ignore me lol

In pratice with cams, which is what Marty based this entire concept off of, a higher ratio rocker relocates the fulcrum point of the lever lower and closer to the valve stem. Reducing the depth of the support, as is being done, would move the fulcrum point of the intermediate lever away from the valve stem... This is the opposite of what you'd want to do if your goal is to increase valve lift and top end power (this 400whp goal they are stating). By decreasing the ratio, as it appears has been done, you may pick up low end torque. Low end torque is definitely one area the n55 does not need help with... or a boosted N52...

I'll wait to see how the results play out. The N52 picked up a few WHP apparently, but again, that was probably just from BPCs tune. They didn't exactly break any N52 records for whp on the tested car. Plenty of N52s are over 238whp without MILVS. Also, such a small whp difference on a dyno could've just been the difference between the highest and lowest dynos of an ENTIRE DAYS worth of runs. My own 128i made 204whp/198wtq on RUN 1 of a dyno session and 214/210 on Run 3 in the same session... I could've claimed I made a million different changes that caused that difference, but the truth is that it was just a normal margin of error. If they manage to break 380whp, and the WHP is carried out further into the upper RPM range, on a PWG N55 I'll pay more attention AFTER seeing the full log to see timing, boost, etc... However, people are always reluctant to post up logs and actually support what they are saying so it may be a long long time before we see that...

[Taskmaster]

Originally Posted by bbnks2

I agree. I was going to post the same sentiment, but I decided not to waste my breath since people only want to hear positive things. If this picks up top-end power on an N55 it is likely to be from the tuning itself and not necessarily from increased valve lift.

There were a lot of questions that went unanswered in the original thread. For instance, when discussing the issue that BPC supposedly ran into on the turbo N52, there was an entire portion of the discussion Marty neglected to take into account in his assessment and calculations of effective valve spring rate. Increased boost means increased cylinder pressure acting on the face of the valve which would have an equalizing effect against the increased boost pressure acting on the back side of the valve when CLOSING. For this reason, the general consensus is that increasing boost pressure is inconsequential to the required valve spring rate needed to prevent valve float. How valve overlap is tuned complicates this matter even further. The only issue I can see with increased boost is pushing the valve open when it is closed and seated... that is not valve float. Machining down the supports will reduce the pre-load of the valve spring, so this issue would become more likely as less force would be required to overcome the pre-load force on the spring and un-seat the valve.

Also, the before and after dyno that they presented of a turbo N52 shows that boost was UP 1psi in the "after" dyno (red line). Increasing valve lift should've resulted in LESS boost at the same WGDC if the MILVs truly reduced intake valve restriction... All I learn from the posted results is that they tuned the car for more boost/wgdc and that's how they picked up power... Or, this mod is actually reducing valve lift and that's why we see the big increase in low end torque and a bit more boost.

I am looking at the pictures and diagrams of how valvetronic works and I can't seem to wrap my head around how machining down the support would have the effects that are being claimed... Seems to me that all machining down the support will do is reduce the amount of return force of the valve spring and reduce valve lift (decreases the effectiveness of the intermediate lever). Or, did I miss something and these new supports are thicker? IF the supports are thicker, then I got this all wrong and you can ignore me lol

In pratice with cams, which is what Marty based this entire concept off of, a higher ratio rocker relocates the fulcrum point of the lever lower and closer to the valve stem. Reducing the depth of the support, as is being done, would move the fulcrum point of the intermediate lever away from the valve stem... This is the opposite of what you'd want to do if your goal is to increase valve lift and top end power (this 400whp goal they are stating). By decreasing the ratio, as it appears has been done, you may pick up low end torque. Low end torque is definitely one area the n55 does not need help with... or a boosted N52...

I'll wait to see how the results play out. The N52 picked up a few WHP apparently, but again, that was probably just from BPCs tune. They didn't exactly break any N52 records for whp on the tested car. Plenty of N52s are over 238whp without MILVS. Also, such a small whp difference on a dyno could've just been the difference between the highest and lowest dynos of an ENTIRE DAYS worth of runs. My own 128i made 204whp/198wtq on RUN 1 of a dyno session and 214/210 on Run 3 in the same session... I could've claimed I made a million different changes that caused that difference, but the truth is that it was just a normal margin of error. If they manage to break 380whp, and the WHP is carried out further into the upper RPM range, on a PWG N55 I'll pay more attention AFTER seeing the full log to see timing, boost, etc... However, people are always reluctant to post up logs and actually support what they are saying so it may be a long long time before we see that...

You neglect to mention that the 238whp N52 was JUST a tune and MILVs - there was no headers, no car deletes or race gas. The previous dyno tuned power for the car was 8-10whp less and 15+Wtq less.

Not saying I exactly know how they work, but I can say they will not work without a tune - apparently the DME is model based and knows what should be happening at every rpm and every load. The Eccentric cam is essentially the TB, and outside of fuel correction, changing the effective lift without telling the DME will not add power.

But after the DME was reprogrammed with the proper lift curve, the car picked up massive power. In the N52, it substantially increased low end torque, on the S55, the low end was slightly softer (longer cylinder fill) barely increased ‘peak’ (VE for the heads and turbo?) and gained about 35whp after peak till redline.

[Taskmaster]

Originally Posted by iminhell1

Looks like that Mike guy is just trying to market something he doesn't full understand. Some of his math is dead wrong.

I would say it's something interesting to watch develop. But It sounds like a bunch of work/cost for minuscule potential gains.

No it’s not.

[bbnks2]

Originally Posted by TheAxiom

Not saying I exactly know how they work, but I can say they will not work without a tune - apparently the DME is model based and knows what should be happening at every rpm and every load. The Eccentric cam is essentially the TB, and outside of fuel correction, changing the effective lift without telling the DME will not add power.

But after the DME was reprogrammed with the proper lift curve, the car picked up massive power. In the N52, it substantially increased low end torque, on the S55, the low end was slightly softer (longer cylinder fill) barely increased ‘peak’ (VE for the heads and turbo?) and gained about 35whp after peak till redline.

I've had a chat with a few people who were able to show their modified parts and explain things a bit better. Looks like Marty is just filing down the mounting surface to make the support sit lower. Makes much more sense now. I was under the impression that the surface where the intermediate lever sits was being filed down which would be counter-productive to producing more lift. Then again, I believe he has to be filing the support down as well to shift the intermediate lever pivot point over a bit... Still not 100% sure on that.

I guess I was more concerned about what BPC had said about the MILVS on their turbo N52. N55 uses the same valve springs, so, any issue BPC ran into on their boost N52 would arise in an N55 with an upgraded turbo... And, not knowing exactly what Marty is doing means I don't know exactly what else modifying the support is doing. Like, potentially putting more or less pre-load on the valve spring necessitating a change in spring rate? Just about all cam modifications require re-spec'ing the valve springs to match... Hopefully we get some more results in soon.

And, I agree with the above poster that most of what Marty posted was conceptual in nature and he hadn't really applied the principles properly in relation to what he was trying to state...

[Mike.]

Originally Posted by iminhell1

Looks like that Mike guy is just trying to market something he doesn't full understand. Some of his math is dead wrong.

I would say it's something interesting to watch develop. But It sounds like a bunch of work/cost for minuscule potential gains.

lol i didnt do any math and wasnt marketing anything, just thought it was interesting