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"...Understand Volumetric Efficiency..." and your ECU

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Old Aug 6, 2023 | 09:50 AM
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From: "The Other Arizona"
"...Understand Volumetric Efficiency..." and your ECU

My buddy forwarded the new video linked below this morning, published earlier today by a guy who has produced many super interesting videos previously. I especially like how he visually explains the relationship of volumetric efficiency to AFR both on normally aspirated and boosted (turbo or supercharger) engines. This topic applies to all MINI models and engine variants, so I'm posting here vs in the 1st Gen subforum.

I think this is a good demonstration of how flashing a "canned tune" isn't the optimal approach vs a custom tune specific to engine modifications. In my own case, known mods including exhaust, pulley, intercooler along with JCW-spec injectors and spark plugs plus perhaps unconfirmed cylinder head work. As have many forum members here and in Europe, @adriancl in Romania performed a custom remote tune on mine with objectives of peak efficiency rather than peak power. Flashing my OEM S-spec ECU to JCW-spec was an option, however doing that wouldn't have accounted for differences on my R53 vs that of an OEM JCW. It would be cool if Adrian comments on this video with his insights and perspectives, noting he also performs remote tunes on other than W11 engine variants, i.e., normally aspirated and turbocharged.

 
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Old Aug 6, 2023 | 10:54 AM
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Just my opinion

Is a nice video.But.....Siemens ECU don't use Volumetric Efficiency.As i saw the guy use a non stock ECU and also wide band O2 sensor.From over 20 years cars have narrow band O2 sensor.You can't use the intake pressure as axis for any kind of fuel injected control , because is not realistic, you need to use the air amount because that is the real parameter need to know when you set a desired AFR.R53 Siemens ECU use boost pressure and intake air temperature to calculate the real air amount.Most of modern cars use a Mass air flow sensor in conjunction with a boost pressure sensor.I'm not agree to run in closed loop-partial throttle- with low AFR values, no need extra power.In open loop-wide open throttle- engine run without the intervention of O2 sensor, just use a fuel map dedicated to WOT.
I saw few software used by "customized ECU", In my opinion
they are at the level of the 90s , not the best choice for a 21st century car.
 
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Old Aug 6, 2023 | 01:50 PM
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It reminds of my TEC II ECU programming days.

I will say it is not as easy to tune as he leads to believe. Tuning to rich gives you a 'bleah', tuning to lean gives you 'detonation'. Better to be to rich then lean, so you tend to error on that side. Most guys try to stay within a safety net of optimal ( ie a little richer than optimized ). I heard from some of the GM engineers in 90's - they would blow up at least 3 engines getting the real world map and then backing off. I myself blew one engine on a dyno - but used engines were cheap back then and one could replace them in the car in half a day.

Plus there is dyno tuning vs road tuninig. It is great when you have an airport runway to tune off of !!

Also - the table he presented was reasonably curvilinear and ideal. I recall seeing gaps and holes in that table do to some engine idiosyncrasies. So one learned the craft of smoothing out the around that hole to avoid engine hiccups. I am guessing engines have gotten better with the maps being more continuous. We used to super charge and turbo charge 1st gen miatas - and well out of the 30% range. There were a few of these holes in that map. The more you modify your car, the more you need a custom tune. Or at least adjustments off a canned one. I 100% agree on data logging on real world driving.

Kind of luck going to class, then trying to do it in a lab. It was never that clean, BTW - Forced Induction raises the risk factor quite a bit.

Now this was a while ago and engine ECU's have gotten smarter - so can catch these things now.
 
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