Vanos Tuning

all4bspinnin

Corporal
Jun 12, 2017
136
So, I've been out of the game for about 2 years and am just getting back into it. I am curious, what is everyone using now a days for their vanos?

I was previously using a modified map based on this thread http://www.n54tech.com/forums/showthread.php?t=21695

Have there been any other "discoveries" of what works best since then?
I have a couple tricks that I use when tuning vanos. It really depends on the turbo, manifold, etc. That will determine when i cut off spool mode. After that, I transition into widening the LSA. Most of the power you'll see is in the intake cam. I've found the exhaust cam helpful but not nearly as much. Adjusting the exhaust cam does help with removing pesky cylinder timing corrections. The factory spool mode tables are pretty good so make sure you use them.
 
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Jboyorak

Private
Nov 6, 2016
48
Maine
I have a couple tricks that I use when tuning vanos. It really depends on the turbo, manifold, etc. That will determine when i cut off spool mode. After that, I transition into widening the LSA. Most of the power you'll see is in the intake cam. I've found the exhaust cam helpful but not nearly as much. Adjusting the exhaust cam does help with removing pesky cylinder timing corrections. The factory spool mode tables are pretty good so make sure you use them.
Thank you for the reply. I have always run spool mode(and lean spool too). I have never saw the need to get rid of these. They are tunable tables that you can use to your advantage. It's good to know about the exhaust cam changes. I'll play around with these tips next time I get some "dyno" time.
 

Twisted Tuning

Lieutenant
Platinum Vendor
Oct 25, 2016
844
New York
Vanos, as stated, is completely dependent on setup. Do believe the hype of people saying "these are the best settings". Fact is every setup is a little different. And it takes time to find the sweet spot for a particular setup.

And always make use of spool mode. I don't see why anyone wouldnt use it. unless they just don't understand it. But i have seen people disable it.
 
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Jboyorak

Private
Nov 6, 2016
48
Maine
Thank you Twisted. I did quite a bit of virtual dyno testing on my old tune with different vanos changes years ago. But this was when I was mostly stock. I used to do a 3rd gear run for a dyno graph and a 1-3 gear run for acceleration data.
 

all4bspinnin

Corporal
Jun 12, 2017
136
Thank you for the reply. I have always run spool mode(and lean spool too). I have never saw the need to get rid of these. They are tunable tables that you can use to your advantage. It's good to know about the exhaust cam changes. I'll play around with these tips next time I get some "dyno" time.
Definitely. Vanos is awesome. The stock VANOS is pretty decent out of the box but definitely more power to be had. Before you get on the dyno, to save you tune time, you could have a couple bin files ready to go so you could flash and log.
 

Twisted Tuning

Lieutenant
Platinum Vendor
Oct 25, 2016
844
New York
Street tuning a car is always needed at some point. Dynos always will put different load on a car than a real street. so many car can react completely different between street and dyno.
 

[email protected]

Specialist
Free Vendor
Apr 1, 2017
70
Street tuning a car is always needed at some point. Dynos always will put different load on a car than a real street. so many car can react completely different between street and dyno.
You can say that again ...

It can be at times a PITA though when I had to do the pulls for the customers and they have weirdly tuned suspensions or exhausts that make me feel like I am on a boat with fog horns ...
 

impuls

Specialist
Jan 28, 2018
53
What is actually the theory behind increasing the overlap and opening the exhaust valve later to improve spool?

Doing the opposite seems more logic:
-Avoid overlap to not cool exhaust gas and reduce
pressure.
-Open exhaust valve early to release expanding gases into the exhaust and increase pressure.
 

Rob09msport

Captain
Oct 28, 2017
1,151
Monroe CT
I would think you want to push unburned mixture into the turbo so more thermal expansion plus you don't want back pressure if you want to accelerate the turbo. This is just a guess with no basis but what in see in my thought bubbles
 

impuls

Specialist
Jan 28, 2018
53
Could be the explanation, but every source I found mentions that overlap is bad for spool and advancing intake and exhaust is what you want to do.

So what is the different with the N54 resulting in improved spool by retarded exhaust valve timing?
 

Hydra Performance

Corporal
Free Vendor
Jan 31, 2017
249
Increasing overlap to improve spool usually works early on in the RPM range when there is a positive pressure differential cramming more charge into the combustion chamber and increasing VE - i.e. boost > exhaust manifold pressure. This is usually only the case around or shortly after full boost.
 

Rob09msport

Captain
Oct 28, 2017
1,151
Monroe CT
Increasing overlap to improve spool usually works early on in the RPM range when there is a positive pressure differential cramming more charge into the combustion chamber and increasing VE - i.e. boost > exhaust manifold pressure. This is usually only the case around or shortly after full boost.
Like reverse scavenging effect right ?
 

Hydra Performance

Corporal
Free Vendor
Jan 31, 2017
249
Yeah if you like, end result is the same :)

At the end of the day the engine is an air pump, whose volumetric efficiency is strongly affected by Pi/Pe (inlet manifold pressure/exhaust manifold pressure), all else being equal. This is why your typical turbocharged torque curve exhibits peak torque shortly after peak boost rpm and gradually tapers downwards with increasing rpm. I've attached an interesting little .pdf from my collection detailing this, for your reading pleasure...
 

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