08-12-2012, 07:18 PM #1
N54 Timing Corrections Discussion
Put up a new post on our blog discussing timing corrections a bit and comparing to a sample datalog from a stage zero tune. Sharing the content here as well in case anyone would like to discuss. I didn't want to go into too many details here, point was to compare some of the tuned datalogs to a 100% bone stock datalog which also corrects under WOT as well as cruise/part throttle. This article may be boring to some of you veterans but to someone new learning it might be a good start:
BMW N54 – CYLINDER TIMING CORRECTIONS AND TUNING FOR MORE RELIABLE POWER
There seems to be a lot of discussion on timing corrections on the N54 and what they mean. Are they bad? Will my engine go kaput if I have some corrections occuring? What happens when my meth isn't flowing right and corrections happen? Etc etc etc.
If you've ever had a chance to datalog a tune on your N54 extensively (and yes, your 100% bone stock N54 with zero modifications or tuning also has a tune, only in that case the OEM one) and done so in situations such as Wide Open Throttle (WOT) as well as cruise and part throttle you'd quickly realize that corrections happen under all of these scenarios irrespective of the driving situation.
In an attempt to answer some of those questions and clear some confusion let's just concentrate on what BMW themselves did at the factory after countless hours of research and development and in the end flashed your original/stock BMW DME/ECU and gave you warranty bumper to bumper for 50,000 miles of any driving you wish to do (as long as you don't modify it of course).
In order to get our data we'll use the Cobb AP unit and datalog a STAGE ZERO map. All the OEM tuning parameters in that map are 100% STOCK as they came from the factory.
Upon looking at the above STAGE ZERO datalog you'll notice that even the DME programming that came originally from BMW encounters timing corrections. This datalog shows a run under Wide Open Throttle (WOT) where timing corrections happen on cylinders 1, 3 and 5. Boost is stock hitting 7psi tapering to 5psi at above 6k rpm.
In conclusion, timing corrections are part of this platforms elaborate timing control and are not necessarily bad for your engine. No one in their right mind can say that the original BMW programming will make this motor die after a few WOT runs or an all out day at the road course. In addition to that a number of piggyback tuning solutions have run these engines to significantly high power levels without ANY timing remap without any documented engine failures and they encounter timing corrections every pull (only you may not be aware of them as you can't datalog them but they're easily spotted if even timing on cylinder 1 is datalogged).
When it comes to tuning for more safe reliable power from these cars/engines we rely on all the information in these datalogs we can get. From our extensive testing on the road and on the dynos we know where a certain car on certain octane in certain conditions and with certain modifications SHOULD be. That is what comprises our BASELINE and we usually use the Off The Shelf (OTS) maps from Cobb as a great tuning starting point. From there we look at datalogs under various driving conditions such as Wide Open Throttle (WOT) and adjust parameters in the map accordingly always ensuring we stay within turbo compressor efficiency maps (i.e. not overstress them by adding more heat vs power) and don't over-advance the ignition timing for a given octane at the given boost levels.
In the end, striving for zero timing corrections out of your tune you're leaving potentially A LOT of safe reliable and consistent power on the table and on top of that it may or may not even be possible zero them all out at all times no matter what octane/boost/timing/afr you run. What it comes down to is that this is just another metric we refer to during our tuning process. Pushing reliable power further while always looking for the right balance of all running parameters for your particular engine/car is what it comes down to in the end and timing corrections are only part of that story.
If BMW's own original tuning is allowed to have some timing corrections, well, we won't pretend we can do it better than them.
Enjoy your N54s, some timing corrections are A-OK!
Last edited by dzenno@PTF; 08-12-2012 at 08:10 PM.
08-12-2012, 09:40 PM #2Member
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Nice... thanks for the blog! It's comforting to know I'm not the only one getting some timing corrections, even on stock maps... lets get this protune done!! Jake's been great!
08-12-2012, 10:32 PM #3
Nice contribution, thanks!
What's the highest timing advance you've hit on any N54 map? Have you advanced any tunes beyond MBT and then had to back down for find power again? If so, what advance was MBT found at say, 5000rpm?
08-12-2012, 11:04 PM #4
Highest timing I've ran so far on my own car was a similar to stock curve. When custom tuning every car we move around timing to find MBT for that particular car's boost profile octane, mods and conditions as its all really different. As for 5k rpm MBT I cant really put a number against it as it can vary depending on the items already mentioned. I'll be doing E85 tuning on my own car with RBs and other goodies hopefully soon too and I'll let you guys know how that goes as usual
08-12-2012, 11:58 PM #5
Danced a 5 mile circle around that one I gotta say I learn more about aggressive tuning by reverse engineering shiv's logs than I do asking directly! Well, keep us posted with logs I'm genuinely interested.
08-13-2012, 09:53 AM #6
08-13-2012, 10:13 AM #7
I'm just being reasonable and careful in what I post in terms of tuning "tips" as with ATR mistakes in say the timing table can be very costly.
Don't you think it'd be foolish of me to answer saying "X number of degrees for MBT at 5k with E85" somewhere when I have no idea about the rest of the tuning parameters or modifications on a given car and/or how your car responds to your octane? Others may just open up ATR and slap X timing in some cells and then come back on here and say dzenno posted it was ok to run 12-15degrees and now look at my $#@!ty logs
Nothing wrong with looking at another car's datalogs and comparing with your own, taking it to the dyno and realizing where MBT sits for a given car's setup.
Last edited by dzenno@PTF; 08-13-2012 at 10:34 AM.
08-13-2012, 12:12 PM #8
Difference is cylinder pressure is far higher at 17 psi than stock. Then again we've seen plenty of cars hit that not even knowing their meth kit isn't working without any blown motors so who knows
08-13-2012, 12:35 PM #9
How much higher is cylinder pressure now that they are at stock boost and stock timing compared to 17psi and stock timing? How different is a 3.x timing pull at 7psi vs a 3.x timing pull at 17psi given the same timing curve with respect to cylinder pressures. How does it change with load vs. rpm vs. octane and how does meth/water injection impact it?
I'm not expecting an answer as no one has ever published anything in detail on these. The point of the above post was to simply shed some light on some sample stock tune datalogs when it comes to timing corrections and the DME reacting a very similar way in a tuned car to a stock car and to show that the engine will not just fall apart if they see some corrections at times as some fear.
It'd be really fun to place cylinder pressure probes inside the chambers and get some of that data for the N54 too. Now that the cylinder head is still off my block it might be a cool thing to add in the process maybe if not too expensive. Any recommendations?
08-13-2012, 08:35 PM #10
08-14-2012, 12:00 AM #11
If someone asked ME the question I asked, I suppose I'd say "well I find MBT at about 15 degrees advance @ 5krpm on a 50/50 summer mix of E85 and 93, at around 12.5:1 equiv AFR and a load of 180." <<< do you find this to be somewhat similar to the cars you've tuned..?
08-16-2012, 10:24 AM #12Member
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At what point do you worry about timing corrections? My understanding is that you worry when you see them over multiple cylinders at the same time at WOT. Also, if the reduction value is 4 or over and not reducing over rpms. Thoughts?
08-16-2012, 10:38 AM #13
Zasquatch 's new excel spreadsheet actually...take care of the really red areas and back timing out from your timing map if/when you get too aggressive and those show up...otherwise you should be fine and some timing corrections can be safely ignored especially on pump gas, without making the tune overly conservative/dead