N54 Using VANOS to remove EGR

[corbanistan]

So EGR in the N54 is done via VANOS, specifically high valve overlap at cruising loads. I always change VANOS values in that range to remove overlap. Anyone else do this? Apparently, it will also prevent intake valves from getting dirty so quickly.
I know there's been discussion about this in other forums which no longer exist, so I thought I'd move the discussion over here. What are your arguments for/against?

 

[TiAgAu]

Show us your Vanos!.... Tables.

So removing overlap would be to have intake and exhaust at similar values?

Forgive my noobness will be interesting topic.

 

[corbanistan]

Nothing special, mostly stock because I'm still on stockers, except for cruise.

 

[Jeffman]

I think this is a great topic. I had followed VANOS adjustments on the other forum years ago when the platform was newer. I had adjusted my VANOS Spool tables for better low-down torque and blended the values into the main table at the spool max rpm. Controlling EGR in the main table as you’re doing is very interesting. Supposedly it changes fuel consumption - have you noticed any changes to fuel consumption?

 

[corbanistan]

I think this is a great topic. I had followed VANOS adjustments on the other forum years ago when the platform was newer. I had adjusted my VANOS Spool tables for better low-down torque and blended the values into the main table at the spool max rpm. Controlling EGR in the main table as you’re doing is very interesting. Supposedly it changes fuel consumption - have you noticed any changes to fuel consumption?

Yeah there was a great discussion with Excel table data on a different forum but it's lost now since it was shut down (y'all probably know which one). In terms of fuel consumption, I haven't noticed a change so far, although I don't really pay attention anyway. Car has said 20.4mpg combined for a while now.

Do you have aftermarket turbos Jeff?

 

[jzx_andy]

I don't have much to add, other than to mention PeteJ from e90post gave a simplified explanation of factory VANOS in his build thread. This may help some gain a basic understanding of the system and how it could potentially affect fuel economy and carbon build up on N54's:

So BMW uses VANOS mainly for efficiency not for power. Exhaust gas is inert, and doesn't have much oxygen for combustion, the DME uses the VANOS solenoids to control the valve opening time to create a slight overlap between the exhaust and intake cams.

This will allow some of the exhaust gas to recirculate back inside the cylinder, and go backwards towards the intake manifold, instead of having all of exhaust gas escaping out of the exhaust valves.

On the next combustion cycle, when fresh air comes through, the cylinders won't be completely filled up with fresh air, they'll be partially filled with fresh air and partially filled with recirculated exhaust gas from the previous combustion cycle.

This effectively reduces the engine size, because exhaust gas is inert, so if you fill 20% of the cylinder capacity with inert gas, you've effectively reduced the size of the engine from 3.0L down to 2.4L, so it improves fuel economy by making it behave like a smaller engine.

The above, is why BMW has never bothered with all these cylinder deactivating/disabling techniques that American and some Jap car manufacturers applied to their engines.

Downside to the above, the engine head runs hotter when EGR is active, because the exhaust gas is very hot obviously. The other discovery, a friend of mine found out that if the EGR is disabled, the engine doesn't require to be walnut blasted as often. The theory is, the hot exhaust gases flowing back through the intake valves, cause the oil film on the intake valves to get caked on the valves forming that solidified carbon powder you see on the intake valves and ports. After disabling EGR, intake valves look spotless after 13,000km. They just have a slight grey-ish shade, I'll wait till I've put 30,000km on it since reducing EGR and recheck.

I didn't it disable it completely, only just reduced it by significant margin. I haven't been paying attention to fuel consumption, so I can't comment on that, but I reckon there'll be a slight increase with EGR reduced. Wrong cars to buy for fuel economy anyway haha

When the engine is underload, or any situation where you're hard on the throttle, the DME disables EGR immediately and cylinders gets fed fresh cold compressed air for best power output.

BMW 3-Series (E90 E92) Forum - View Single Post - Pete's toy with a licence plate - E92 335i Build Thread

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www.e90post.com

 

[studio54]

Very interesting thanks, missed that on the other forum which no longer exists, so I am glad you bring it here

 

[Jeffman]

Yeah there was a great discussion with Excel table data on a different forum but it's lost now since it was shut down (y'all probably know which one). In terms of fuel consumption, I haven't noticed a change so far, although I don't really pay attention anyway. Car has said 20.4mpg combined for a while now.

Do you have aftermarket turbos Jeff?

I’m pretty sure I incorporated some of suggested VANOS values in my custom bin, which I had shared in another thread this evening. I’ll put it here as well for people to look at (don’t use it however, it’s a FlexFuel IJEOS map with 100% WGDC for max boost pressure).

BTW, I still have my stock turbos and the engine is in great shape after 14 years / 72K miles. I believe this is partly due to my never going WOT until oil temps were at least 210F.

 

[corbanistan]

I’m pretty sure I incorporated some of suggested VANOS values in my custom bin, which I had shared in another thread this evening. I’ll put it here as well for people to look at (don’t use it however, it’s a FlexFuel IJEOS map with 100% WGDC for max boost pressure).

BTW, I still have my stock turbos and the engine is in great shape after 14 years / 72K miles. I believe this is partly due to my never going WOT until oil temps were at least 210F.

That's one of the best things you can do to preserve any engine. I'm at 115k miles with no issues and stock turbos (besides a little rattle). Always wait for movement on the temp gauge before becoming Mad Max.

 

[corbanistan]

I don't have much to add, other than to mention PeteJ from e90post gave a simplified explanation of factory VANOS in his build thread. This may help some gain a basic understanding of the system and how it could potentially affect fuel economy and carbon build up on N54's:

BMW 3-Series (E90 E92) Forum - View Single Post - Pete's toy with a licence plate - E92 335i Build Thread

Forum for BMW 1-Series 3-Series 5-Series 7-Series M3 M5 M6 Z4 X1 X3 X5 X6 Z2 Z4 325i 330i 335i 535i 550i 755i BMW Forums

www.e90post.com

I have regular maintenance to do soon so I'll check my valves to see how they're doing. It's been about 15k miles since cleaning.

 

[rac]

fuel consumption must change if keeping AFR constant and airflow is increased (by reducing EGR).

dont think many tuners on average (as in industry wide) would be get too worked up about managing fuel economy via EGR etc., bc its not really on the customers priority list so in general with dual cam timing platforms the exhaust ends up being fairly flat by comparison to intake and intake is heavily advanced coming off idle then slowly tapers off and maybe all out by redline. intake cam timing being much more sensitive to rpm than exhaust timing. outside of that general picture the oem engineers will be fine tuning fuel economy and emissions in other areas of the map .

 

[corbanistan]

Just to add something I remember reading on a different forum about this: one of the posters had said that he retards intake cam but left exhaust as it was. This of course does still reduce overlap (though not as much) but I think if I remember correctly he did this to preserve drivability. Not positive about that, but I haven't noticed a change in drivability with both intake and exhaust changed.

 

[Jeffman]

I suspect our top tuners (Wedge, Motiv, etc.) all know a great deal about how to tune the VANOS tables for max power, driveability, etc. Too bad their tunes are locked - but we should be able to reverse-engineer those tables by running one of the locked tunes, e.g., an OTS MHD map or a locked custom tune of theirs and logging the two VANOS IN and OUT request tables under various conditions. I’m going to try this for the MHD v10 Stage 2+ and compare to the one I posted. I will call this “The VANOS Project”.

I will report my findings. Stay tuned!

 

[carabuser]

I suspect our top tuners (Wedge, Motiv, etc.) all know a great deal about how to tune the VANOS tables for max power, driveability, etc. Too bad their tunes are locked - but we should be able to reverse-engineer those tables by running one of the locked tunes, e.g., an OTS MHD map or a locked custom tune of theirs and logging the two VANOS IN and OUT request tables under various conditions. I’m going to try this for the MHD v10 Stage 2+ and compare to the one I posted. I will call this “The VANOS Project”.

I will report my findings. Stay tuned!

You'll probably find they either copy the old COBB tables or just use the stock ones. I think anyone who's done testing came back to the conclusion that stock tables are already optimised for maximum power. Afterall BMW aren't going to any power on the table unless there's a gain like lower emissions and emissions tests don't look at max power scenarios.

For single turbos there is optimisation to made for faster spool, but on twins the only adjustments that can be made are to reduce overlap during cruise. You sacrifice fuel mileage but apparently get less carbon buildup on the intake valves.

 

[corbanistan]

I suspect our top tuners (Wedge, Motiv, etc.) all know a great deal about how to tune the VANOS tables for max power, driveability, etc. Too bad their tunes are locked - but we should be able to reverse-engineer those tables by running one of the locked tunes, e.g., an OTS MHD map or a locked custom tune of theirs and logging the two VANOS IN and OUT request tables under various conditions. I’m going to try this for the MHD v10 Stage 2+ and compare to the one I posted. I will call this “The VANOS Project”.

I will report my findings. Stay tuned!

They run stock tables, @carabuser is right. But another thing you can do if you'd like is decrease overlap during deceleration to increase engine braking a little bit.

 

[studio54]

You'll probably find they either copy the old COBB tables or just use the stock ones. I think anyone who's done testing came back to the conclusion that stock tables are already optimised for maximum power. Afterall BMW aren't going to any power on the table unless there's a gain like lower emissions and emissions tests don't look at max power scenarios.

For single turbos there is optimisation to made for faster spool, but on twins the only adjustments that can be made are to reduce overlap during cruise. You sacrifice fuel mileage but apparently get less carbon buildup on the intake valves.

Yes, out of curiosity I just opened some (of the famous V5-V6 leak) BINs in TunerPro, and it does not look like they use stock ones, but yes, they seems to use slightly modified tables of COBB or tables we find in the old V8Bait excel file (at least for those revisions V5 V6, if Jeffman log V10 we could find out if they use something really new, but would be surprising).

That said, as an innocent question & for maximum power, is your opinion to leave vanos tables completely stock, instead of using modified ones ?

 

[carabuser]

Yes, out of curiosity I just opened some (of the famous V5-V6 leak) BINs in TunerPro, and it does not look like they use stock ones, but yes, they seems to use slightly modified tables of COBB or tables we find in the old V8Bait excel file (at least for those revisions V5 V6, if Jeffman log V10 we could find out if they use something really new, but would be surprising).

That said, as an innocent question & for maximum power, is your opinion to leave vanos tables completely stock, instead of using modified ones ?

One of the changes in the newer maps is a return to stock tables. People just copy and paste without testing so the bullshit cobb tables persisted for a long time.

You can mod them if you want less EGR but changing the higher load areas will gain you nothing in terms of power. They are already maxing out the physical adjustment range.

 

[studio54]

One of the changes in the newer maps is a return to stock tables. People just copy and paste without testing so the bullshit cobb tables persisted for a long time.

You can mod them if you want less EGR but changing the higher load areas will gain you nothing in terms of power. They are already maxing out the physical adjustment range.

Ok cool thanks, it's very interesting since the V10 revision seems to max out the power, on my car at least, beside the butt dyno which means nothing, I got my best times (I haven't a Dragy or something but I use log to compare my times)

 

[Krampus]

One of the changes in the newer maps is a return to stock tables. People just copy and paste without testing so the bullshit cobb tables persisted for a long time.

You can mod them if you want less EGR but changing the higher load areas will gain you nothing in terms of power. They are already maxing out the physical adjustment range.

Does this concern all VANOS tables or only VANOS intake (moving) warm and VANOS exhaust (moving) warm?

 

[carabuser]

Does this concern all VANOS tables or only VANOS intake (moving) warm and VANOS exhaust (moving) warm?

I don't think the other tables have ever been changed. The spool ones are modded for single turbos but no OTS maps would change them.