Dinans big secret about 540i intake manifolds!?

[mr10ger]

hey there. can anybody tell me how i would probably get best results from tuning the full throttle vanos map after M60 swap? i dont have a dyno nor a logging tool and just by theoretical reflections, i could get benefits and disadvantages both at the same time from retarding and advancing the intake cam in higher rpms. stock, the timing is set to low overlap on low rpm to biggest overlap on mid rpm to low overlap on high rpm. i took a look on a tune from an cammed engine with M60 intake, headers and custom exhaust, there i found cam timing to be set for more overlap (not max, but more) up to the redline. i have no idea on what lobe the cam was set mechanically though. i have also read that more overlap helps on high rpm, but also retarding the intake cam will help on high rpm. i got to the point that i will have lower air velocity with bigger runners, so the piston moving upwards may have a bigger impact on pushing air back into the inlet again when retarding the cam. on the other hand, opening the valves too early may result in residual gas expanding to the inlet, which could be avoided by headers and custom exhaust, so maybe this is the reason for the cam tuning on the tune i took a look at.

if i think a more practical way, the stock enginge has had the most torque somewhere on mid rpm where we had the biggest overlap. changing the manifold leads to pulling the torque to higher rpms, so i could just do the same with the cam timing, take the stock values and just pull them up to higher rpms, which would again lead to higher overlap at higher rpms...


any suggestions or maybe somebody knows which way some tuners chose for only the manifold mod?

[R Shaffner]

Just so I understand, you're talking about:

• An M62TU engine that you put an M60 intake on.
• Changing the VANOS map to extend the range when the intake cams are advanced by the VANOS system.
• (Not about changing the initial static position of the cams.)

Is that right? Interesting idea.

When I first head of variable valve timing, that's what I thought the goal would be: to give normal cam timing for smooth idle and everyday driving, and to give more overlap when one wants a lot of power at higher rpm (like race engines).

Then I read BWW's literature about the M62TU. Completely different from what I was expecting. As you probably know, the intake cams advance in the middle of the rpm range and return to normal (same as idle) at higher rpm. The goal was higher mid-range torque, not more power at higher rpm.

I wonder if this is a feature (or limitation) of the single VANOS -- that there's not much benefit of advancing the intake cams for higher rpm ranges if one cannot also advance the exhaust cams. I'm eager to hear others' thoughts on this.

[mr10ger]

yes, i will never touch the cam position again after i have done timing chain / tensioner etc and vanos revision. well, i think it actually is the goal to use rather "racy" cams for high power while still having torque in the mid range for everyday driving. funny thing is, that they decrased opening angle for the vanos engines as far as i know, so they seem to really get the same power out of "worse" camshafts with vanos.

my goal is to just adapt the vanos maps to the mod.

i am almost sure that theres not much that can be done with stock initial position and stock engine just by re-adjusting vanos timings. but there is a influence to the fluid dynamics by changing the intake and so a (software-based) re-adjustment of the cam timing should be beneficial with this mod. IMO theres not much you can get out of a N/A engine by advancing ignition or fuel enrichment, those are close to optimum on a stock engine of these model years. but adapting cam timing to other hardware changes could bring noticeable effects.

[topaz540i]

Easiest to just get the m60 manifold swap tune software from ESS Tuning.

[R Shaffner]

DUDMD (search this forum) is also known for good tunes with the M60 manifold.

Back to your original question: Isn't there a big difference between using overlap and opening the valves earlier with racing cams, and simply advancing the open/close timing for normal street cams? Don't racing cams have different profiles and longer open durations?

It might help to open the intake valves early, in some situations, but I doubt it ever helps to close them early.