[mrnuke]

I'm more of a lurker here after buying a 2011 e90 6mt and enjoy the community a lot. I've done a lot of reading and know that justpete and hassmaschine are really the ones pushing outside the box for the n52 other than the normal power adders.

I work in NASCAR on the weekends as a pit crew member, and know a lot of people who are great machinist with access to CNC's who love any type of car projects. I've seen some who had custom cam's ended up locking the valvetronic to max lift for their custom cam solutions. I was wondering what prohibits them from working at lower eccentric shaft angles, as well as if the stock cam could work, just tweaking the lobes on the eccentric shaft for more lift as it opens up more would work as well? What would need to be done on a more aggressive cam to make it work with the valvetronic system? Looking forward to the discussion!

[yupetc]

Did you read up on the MILV's here? CobraMarty pioneered the project got it done for us. It sounds pretty congruent to what you're trying to achieve.

[mrnuke]

Originally Posted by yupetc

Did you read up on the MILV's here? CobraMarty pioneered the project got it done for us. It sounds pretty congruent to what you're trying to achieve.

While Marty has done a great job, this is for intake and doesn't mess with timing and adds 1mm or so of lift. I was looking at both intake and exhaust sides of things and going more than 1mm to maximize power

[hassmaschine]

I wouldn't say the idea of cams for the N52 is completely dead, but Marty's MILVS makes it a lot less necessary given how inexpensive they are and relatively simple to install (compared to a cam, especially the intake side). Basically, it's an uphill battle - even if you have a buddy who can make cams on the cheap.

Also, I've said this before but without headflow data there's no point in designing a custom cam, since we don't know what the head actually can use (or what sort of gains could be made with porting, etc). Increasing lift or duration blindly with the expectation of a big power gain isn't likely to work out.

Fortunately, I have a buddy who has Pete's head (actually, I think it's BPC's). I don't have a time frame but he'll get the thing flowed eventually, then we'll have something to work with.

[Taskmaster]

Originally Posted by hassmaschine

I wouldn't say the idea of cams for the N52 is completely dead, but Marty's MILVS makes it a lot less necessary given how inexpensive they are and relatively simple to install (compared to a cam, especially the intake side). Basically, it's an uphill battle - even if you have a buddy who can make cams on the cheap.

Also, I've said this before but without headflow data there's no point in designing a custom cam, since we don't know what the head actually can use (or what sort of gains could be made with porting, etc). Increasing lift or duration blindly with the expectation of a big power gain isn't likely to work out.

Fortunately, I have a buddy who has Pete's head (actually, I think it's BPC's). I don't have a time frame but he'll get the thing flowed eventually, then we'll have something to work with.

It's here in Florida...somewhere..

[mrnuke]

Originally Posted by hassmaschine

I wouldn't say the idea of cams for the N52 is completely dead, but Marty's MILVS makes it a lot less necessary given how inexpensive they are and relatively simple to install (compared to a cam, especially the intake side). Basically, it's an uphill battle - even if you have a buddy who can make cams on the cheap.

Also, I've said this before but without headflow data there's no point in designing a custom cam, since we don't know what the head actually can use (or what sort of gains could be made with porting, etc). Increasing lift or duration blindly with the expectation of a big power gain isn't likely to work out.

Fortunately, I have a buddy who has Pete's head (actually, I think it's BPC's). I don't have a time frame but he'll get the thing flowed eventually, then we'll have something to work with.

Perfect, I know MILVS is the way easier option, but being a gearhead, I don't mind hard tasks. With the resources I have around here, I'd love to help spearhead a project that some may find value in. Like one of your threads, I too would love to have a n52 based mini s54 with an ITB/CSL intake type setup eventually.

[Taskmaster]

Originally Posted by mrnuke

Perfect, I know MILVS is the way easier option, but being a gearhead, I don't mind hard tasks. With the resources I have around here, I'd love to help spearhead a project that some may find value in. Like one of your threads, I too would love to have a n52 based mini s54 with an ITB/CSL intake type setup eventually.

Make us an adapter for S54 Tbs.

[Taskmaster]

Question - how similar is the bore spacing for the S54 cams and the N52?

[mrnuke]

Originally Posted by Taskmaster

Make us an adapter for S54 Tbs.

This is probably fairly easy to do. Would love to get the flow numbers and see if porting/polishing has much of an effect, as I know the s54 TB's are a bit larger than the intake channel. Another random thought, but could the signal for the DISA valve opening at certain RPM's ever be coded to a motor that changes intake runner length if we can make some sort of telescopic variable intake runner? Also, would this sort of help solve the velocity issue if we were to port the intake (depends on flow numbers)?

[hassmaschine]

Originally Posted by Taskmaster

Question - how similar is the bore spacing for the S54 cams and the N52?

the cylinder bores are the same (91mm centers). the S54 cams however are completely different. I have a set I could post pics of side by side.

[hassmaschine]

Originally Posted by mrnuke

This is probably fairly easy to do. Would love to get the flow numbers and see if porting/polishing has much of an effect, as I know the s54 TB's are a bit larger than the intake channel. Another random thought, but could the signal for the DISA valve opening at certain RPM's ever be coded to a motor that changes intake runner length if we can make some sort of telescopic variable intake runner? Also, would this sort of help solve the velocity issue if we were to port the intake (depends on flow numbers)?

the #1 throttle will need modified (the mounting point for the first bolt hits the OFH). The rest of it would be pretty simple, just a mounting plate. The ports are a little bigger but it's not a huge difference. To control velocity, you could just close the throttles slightly if needed. They're really only required as a failsafe (and to mount the awesome CSL airbox). You also need a way to mount the S54 throttle actuator.

the DISA setpoints basically just open and close the PWM solenoids for the flaps. You can set the open and close RPM as well as the PWM thresholds for each setpoint - it could be done. But what are you going to vary?

There's little point in porting the stock manifold. It's not an airflow issue anyway - the resonance frequencies just don't work at high RPM. this thing was probably computer designed and tuned, so improving it would be a tall order. Best to just dump it and start from scratch.. it's all plastic anyway.

[atmosphericM]

I don't have a *whole* lot of experience 'tuning' inside of an engine. What's the deal with no aftermarket cams anyway on the N52? They don't like to play nice with the valvetronic system? I think I understand the basics of how changing the intake camshaft can result in more power.. more air in through the intake side by opening the valve more and/or for more time. But is an exhaust cam changed merely to complement the new intake profile (need to get that additional air out)? Is it possible that *either* the intake *or* the exhaust cam on an engine is the 'bottleneck' if you will, and sometimes changing one profile is more necessary? That said, I'd imagine auto engineers design the cams with each other in mind, for optimization. And please forgive me for this super-noob Q.. but are our exhaust cams also valvetronic? Must they both be for the system to work? I ask because I think I noticed that the valvetronic motor is mounted to the exhaust side of the engine.

[mrnuke]

Originally Posted by atmosphericM

I don't have a *whole* lot of experience 'tuning' inside of an engine. What's the deal with no aftermarket cams anyway on the N52? They don't like to play nice with the valvetronic system? I think I understand the basics of how changing the intake camshaft can result in more power.. more air in through the intake side by opening the valve more and/or for more time. But is an exhaust cam changed merely to complement the new intake profile (need to get that additional air out)? Is it possible that *either* the intake *or* the exhaust cam on an engine is the 'bottleneck' if you will, and sometimes changing one profile is more necessary? That said, I'd imagine auto engineers design the cams with each other in mind, for optimization. And please forgive me for this super-noob Q.. but are our exhaust cams also valvetronic? Must they both be for the system to work? I ask because I think I noticed that the valvetronic motor is mounted to the exhaust side of the engine.

I'm still trying to wrap my head around the wizardry of valvetronic. BPC has a youtube video of the n52 where they do a great job showing you the intake cam and how valvetronic acts on it, as the eccentric shaft is manipulated from 0-100%, the lobes on that gradually change the valve lift. This is what I'm sure is most annoying for cam makers to account for. Would a regrind of the eccentric shaft lobes in essence produce an aftermarket cam type effect?

The exhaust cam is not valvetronic and might be nice to have something with longer duration or more lift to let the engine exhale along with MILVS to take more advantage of what Marty is doing. I figured hassmaschine is the brains behind the n52 and he'd know how it all may work best together. I'm not a FI guy and eventually want to take my own car from daily to weekend track car when I'm done pitting and have more time on the weekends.

[hassmaschine]

Originally Posted by atmosphericM

I don't have a *whole* lot of experience 'tuning' inside of an engine. What's the deal with no aftermarket cams anyway on the N52? They don't like to play nice with the valvetronic system?

I think mostly it just takes a lot more effort with Valvetronic because the rocker ratio is variable, rather than static. That's how it alters lift - the rocker ratio multiplies the cam lift to determine how far the valve opens. a higher ratio means a high lift, and a lower ratio means a low lift (on the N52, this can be from 0.01mm to ~9.9mm).

You need to be able to modify the maximum lift without affecting the minimum lift (or the engine will not idle). That is what Marty's MILVS do.

Most cams are made for one static rocker ratio which determines valve lift, valve timing, and duration from the cam shape. If you have a 2:1 rocker ratio and your cam lift is 5mm, then it's easy to figure out what the lift at the valve is (accounting for factors like valve lash etc).

The MILVS must also alter cam duration and valve timing as a side effect of increasing lift - it's unknown how much effect that has.

I think I understand the basics of how changing the intake camshaft can result in more power.. more air in through the intake side by opening the valve more and/or for more time. But is an exhaust cam changed merely to complement the new intake profile (need to get that additional air out)? Is it possible that *either* the intake *or* the exhaust cam on an engine is the 'bottleneck' if you will, and sometimes changing one profile is more necessary? That said, I'd imagine auto engineers design the cams with each other in mind, for optimization.

It depends on a lot of factors, but often you would change both together. I doubt either is a bottleneck on their own - they are certainly matched together when they were designed. If you get more air in the engine it follows that more air has to get out - but if you add headers into the mix (assuming they are effective at scavenging and not just looking cool), it changes the requirements of the exhaust cam. Also, on top of all of that, we also have VANOS..

And please forgive me for this super-noob Q.. but are our exhaust cams also valvetronic? Must they both be for the system to work? I ask because I think I noticed that the valvetronic motor is mounted to the exhaust side of the engine.

no, the exhaust cam is just a regular cam like the N53, N54, and N55. The cam trays etc. are all the same.

[Taskmaster]

Originally Posted by mrnuke

This is probably fairly easy to do. Would love to get the flow numbers and see if porting/polishing has much of an effect, as I know the s54 TB's are a bit larger than the intake channel. Another random thought, but could the signal for the DISA valve opening at certain RPM's ever be coded to a motor that changes intake runner length if we can make some sort of telescopic variable intake runner? Also, would this sort of help solve the velocity issue if we were to port the intake (depends on flow numbers)?

Technically yes, it could/would be just an RPM based switch, though the DISA works on load/temp/ingnition -etc, so replacing one with the other could work. But I think that would be too much work. A good ITB setup should have consistent gains across the board.

[hassmaschine]

Originally Posted by Taskmaster

Technically yes, it could/would be just an RPM based switch, though the DISA works on load/temp/ingnition -etc, so replacing one with the other could work. But I think that would be too much work. A good tuned velocity stack setup should have consistent gains across the board.

Fixed that for you - I don't want to confuse people

'ITBs' won't do anything for the N52 - the only reason to have throttles at all is a backup in case of valvetronic failure. Otherwise, you could just bolt tuned velocity stacks to the head, which is really why ITBs gain power.

That was my original plan, but I'm not comfortable with a lack of backup. In the case of an eccentric shaft failure, the valvetronic motor moves to a fixed point (by default, it's maximum lift). You could reduce that to a lower fixed position but you'd still have basically no throttle control... that wouldn't be good if you were on a track or a long road trip.

[atmosphericM]

If designing an intake cam is so difficult thanks to the valvetronic complexity, perhaps we could design just an exhaust camshaft, built around optimizing the new-found airflow as a result of MILVS, to couple with them? If the MILVS are resulting in ~10 whp gains, and the custom exhaust cam contributed another 5-10 whp, isn't that about as much as one would get from any sort of camshaft upgrade on a similar spec'd (3L N/A 6 cyl.) motor? I never installed cams on my Z, but I don't remember the gains being all that insane... I want to say it was like ~25 whp when tuned, if that. 15+ whp from 'cams' isn't bad, especially if the package (exhaust cam + MILVS) came in at under a grand.

[atmosphericM]

Trying to visualize it in my noob head but I don't see why a more aggressive cam profile wouldn't simply be 'multiplied' by valvetronic, making it even more aggressive. Thus, a 'slightly' more aggressive cam profile would be perfect when paired with the valvetronic motor. But I'm probably missing something basic and key. *heads to youtube to watch more valvetronic vids*

Originally Posted by mrnuke

The exhaust cam is not valvetronic and might be nice to have something with longer duration or more lift to let the engine exhale along with MILVS to take more advantage of what Marty is doing. I figured hassmaschine is the brains behind the n52 and he'd know how it all may work best together. I'm not a FI guy and eventually want to take my own car from daily to weekend track car when I'm done pitting and have more time on the weekends.

Sounds like we are on the same page. I also share your sentiments regarding N/A motors.

[hassmaschine]

The minimum rocker ratio is almost 0 (but not quite). The maximum is something like 3:1. So if you increase cam lift by 1mm, you increase valve lift (at maximum eccentric angle) by 3mm.

Marty's MILVS work by altering the curve that determines the change in rocker ratio, effectively increasing the multiplier slightly (let's say it's 3.5:1 for discussion), which is how it can change lift without changing the cam. Actually, on some engines people swap the rockers out for ones with a different static ratio which does the same thing.

Probably with all new cams you would also need different rockers, intermediate rockers, and rocker supports. That would be expensive to design and manufacture. There's a reason why all the valvetronic engines use the same parts (N52, N55, S55)...

[atmosphericM]

Originally Posted by hassmaschine

You need to be able to modify the maximum lift without affecting the minimum lift (or the engine will not idle). That is what Marty's MILVS do.

What about bumping up the idle? Isn't that typcal of a cam'd car, anyway? Or is that line a lot finer with the valvetronic?

Really appreciate the detailed reply.

[hassmaschine]

That's done because of increased intake/exhaust valve overlap. We don't have that problem because we have VANOS.

It won't idle properly because the DME needs to be able to reduce lift down to 0.01mm - if suddenly minimum lift is 0.03mm, things are going to go wrong.

[mrnuke]

Originally Posted by hassmaschine

Fixed that for you - I don't want to confuse people

'ITBs' won't do anything for the N52 - the only reason to have throttles at all is a backup in case of valvetronic failure. Otherwise, you could just bolt tuned velocity stacks to the head, which is really why ITBs gain power.

That was my original plan, but I'm not comfortable with a lack of backup. In the case of an eccentric shaft failure, the valvetronic motor moves to a fixed point (by default, it's maximum lift). You could reduce that to a lower fixed position but you'd still have basically no throttle control... that wouldn't be good if you were on a track or a long road trip.

I know this is only a minor thing, but wouldn't you be able to wire an ignition kill switch of some sort if it became a runaway? It would suck to have to trailer/flatbed it somewhere, but that would prohibit the "backup" system from having a total failure.