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Alpha-N in 2020 - some questions for a newcomer

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  • france320isco
    replied
    Originally posted by Konig View Post
    Hello group

    I am preparing to take the leap to that wonderful carbon airbox life. I have been reading and digging and searching old threads, but the information is spread broadly and is often too in-depth for an amateur like me. I want to get some feedback and check my understanding of the different engine management options in conjunction with a carbon airbox and eliminated AFM.

    Context: my car is a stock, recently-refreshed 2.3L US motor. My goal is increased throttle response and induction sound, more power is welcome but not really expected. Unfortunately a big constraint is that I'm in California and need to be able to pass an emissions inspection every 2 years. Therefore, revert-ability is a big factor.

    What I think I understand:
    • Maxx A-N
      • piggyback controller that uses throttle position (alpha) and engine RPM (n) to generate, from an internal table, a 'spoof' number for the AFM that it sends to the ECU
      • used on the race cars back in the day and used on street/track M3s throughout the years
      • crude compared to modern options but apparently robust if set up properly
      • can be tuned and adjusted on the fly with real-time feedback
      • can use closed-loop wide-band feedback and self-tune (to what extent...?)
      • some ECU connector pins need to be modified for installation
      • [unsure] only allows control of fuel?
      • [question] how does this interact with ECU chips? I have an iigomotiv 91 octane for a stock 2.3L. I guess if MAXX is spoofing an AFM value you still need an ECU chip configured for the setup, how would I achieve that? Does anyone make chips anymore...?
      • [question] Markus offers a "plug and play wideband setup" for the Maxx A-N, link here, I'm not sure I understand it. Are all of these pieces (and $500) required to use a wide-band sensor, or is it just offering some convenience or something? Markus tried to help me understand but there may be a language gap
    • Miller A-N
      • uses throttle position and RPM measurements to replace the AFM, but not as a piggyback. WAR chip helps ECU take these new inputs 'raw' and run the car off of them (instead of getting spoofed AFM values), solving what Miller claims as some sort of lag in processing time with Maxx arrangement
      • newer product
      • cannot be tuned and adjusted on the fly with real-time feedback (WAR chip can carry 4 tunes on board), no datalogging
      • does/can not use closed-loop wide-band feedback
      • completely plug and play harness
      • [unsure] allows control of fuel and ignition?
      • [unsure] can be tuned using their software, or done remotely by Miller
    • Miller MAF and WAR chip
      • replaces the AFM with a MAF to get rid of the 'garden gate' intake restriction, use WAR chip to process information from MAF and run the car
      • same tuning/feedback/harness details as Miller A-N above
      • [unsure] from what I read, MAF does not jive with a carbon airbox due to some pressure waves that can come back up the intake and confuse the MAF sensor. Results in poor part-throttle performance. Therefore not really an option for me since I am going carbon box.
    • Full standalone ECU
      • VAC outlines their argument for their particular ECU over A-N
      • I have to imagine a modern ECU gives the best, fullest motor control with the latest modern tech, flexibility with tuners
      • Highest cost option, I imagine has the most setup time?
      • Seems like it would not be compatible with my needs to go back to stock for SMOG every couple years

    This is the high-level understanding I have managed so far. I don't have any insight into the specifics of the different engine management options - which ones control what parameters, have good safety controls and engine protection features, outputs if I wanted an AFM sensor or something, how hard each one is to tune, where I can have them tuned/serviced in the future. From what I hear A-N is "set it and forget it" with a good initial tune, especially in the stable California climate, but I am thinking ahead to what I would do if I had an issue develop a few months after a successful initial install.

    From my understanding so far, it feels like a hybrid Miller MAF/WAR with a carbon airbox would be the perfect combination of plug/play and what I want, but I guess the MAF just doesn't jive with the airbox. If I lived in a different state a standalone would probably be a front-runner option. The fact that the Miller A-N does not have wide-band feedback and cannot be tuned on the fly seem like big drawbacks. So I think I am back to the "vanilla" Maxx A-N option. The main tripping points for me on that are the issues of (1) engine chip to run the car, and (2) re-wiring required to the factory ECU harness that will complicate the SMOG hardware swap.

    Many questions here obviously, if it's not already apparent I've never done any type of engine control / ECU stuff. I am going to have installation and setup done by a shop, but I like to understand what I'm doing to my car, even if I'm not turning the wrenches.

    Other questions that come to mind:
    • Has anyone made a MAF work with a carbon box, perhaps further 'upstream' in the intake where resonances and plenum bounce-back do not impact it?
    • It seems like a skilled operator can map Alpha-N to be reliable, but I'm still a bit confused about how the motor "understands" load differences, whether it's under full throttle going uphill in high gear versus goin full throttle on a flat road in second gear. I believe the intake air temperatures sensor and baro sensor feed into the ECU and can help with changing weather conditions, but I do not understand the "load understanding" story.
    Huge wall of text, if you made it through I'd appreciate your thoughts and input. If I have my facts wrong, or have missed important distinctions, please weigh in.
    Don't know what happened since this but any system you get, provide a knock sensing. The stock ignition advance map Is tuned for the stock afm.

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  • SNWMBL
    replied
    Checked for leaks. Nothing. I think I've nailed it down to the brake booster which explains why I get this heel toe downshifting. I could hear it occasionally affecting revs while i mimicked heel toe while stationary. The check valve itself looks original and it's pretty loose in terms of being able to spin it around while fitted. Diaphragm doesn't feel faulty so I'll replace the check valve and see how that goes.

    Leave a comment:


  • jimmy p.
    replied
    Originally posted by Konig View Post
    Being completely honest I feel the age of the A-N system - in my limited understanding the tuning 'resolution' is simply not comparable to modern ECUs, so part-throttle and corner cases are not quite as smooth as the factory ECU. That said, there is no issue with cold or hot starting, the AFM looks good, and it's smiles and good induction noise every time I go out.
    No slight to your tuner but the system not the problem.
    If you are having any drivability issues or "resolution" issues, thats tuning. A huge part of the tuning process is all the part throttle work. The WOT portion takes 15 minutes. The real tuning chops are all the stuff in the middle.A tuner can spend hours working through the middle of the curve. A well tuned car using A-N strategy is fully functional and wonderful to drive into the corner, off the corner, pedal the car and roll into the throttle.
    If there is a problems its either electrical in the install, mechanical in the engine or most likley the tuning. Its not the system.

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  • Mick
    replied
    That looks pretty typical to me, the AFM is slow to detect quick throttle movements. I would check and make sure that you don't have any intake leaks to be sure something like that isn't making it worse.

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  • SNWMBL
    replied
    Not sure if that video link worked? Here's another link.. https://flic.kr/p/2nc1f5F

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  • SNWMBL
    replied
    It's worse under load but you can see it's rev delay in the vid. Almost wants to bog down before it revs up! Is this a characteristic only Alpha N (and carbon airbox) will solve??

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  • SNWMBL
    replied
    20220402_131652

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  • Mick
    replied
    Originally posted by SNWMBL View Post
    Does the alpha n improve response when blipping the throttle? I find the throttle doesn't like quick stabs when downshifting and I'm thinking that's just a characteristic of the afm not picking up the airflow instantaneously. It's almost like you have to roll into the throttle and give it a split second for the revs to catch up before I can stab at it and have it respond instantly.
    Absolutely, so long as its tuned properly. When I installed Maxx A/N the car was transformed. It was as if the car had been broken and the A/N fixed it.

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  • SNWMBL
    replied
    Does the alpha n improve response when blipping the throttle? I find the throttle doesn't like quick stabs when downshifting and I'm thinking that's just a characteristic of the afm not picking up the airflow instantaneously. It's almost like you have to roll into the throttle and give it a split second for the revs to catch up before I can stab at it and have it respond instantly.

    Leave a comment:


  • SNWMBL
    replied
    Ive read through your thread 3 times! Epic car! Great job documenting work on it and putting miles on the clock.

    Leave a comment:


  • Konig
    replied
    Originally posted by SNWMBL View Post
    Did you end up going with Alpha N in the end Konig ? If so, how did you find tuning and living with it since? From the outside it looks like a simple method of ditching the AFM. Surprised so many have trouble tuning, especially with closed loop wideband! Understandable if you have never tuned anything yourself but if a "pro" tuner cant figure that out I certainly wouldnt trust them with anything else!
    Yes, I did. Take a peek at my tracking thread in my signature for more complete posts and information.

    I had the system installed and tuned by Josh, aka JibbaJabba here on the forum, through his shop in Sacramento. We worked together on the wiring plan to make the system plug-and-play so that the A-N piggyback can be bypassed when SMOG time comes around.

    I am happy to report that I love the response and sound of the car - completely transformative in my opinion - and I successfully ran the SMOG gauntlet three months ago without any hiccups (except for user error). Being completely honest I feel the age of the A-N system - in my limited understanding the tuning 'resolution' is simply not comparable to modern ECUs, so part-throttle and corner cases are not quite as smooth as the factory ECU. That said, there is no issue with cold or hot starting, the AFM looks good, and it's smiles and good induction noise every time I go out.

    Leave a comment:


  • SNWMBL
    replied
    Did you end up going with Alpha N in the end Konig ? If so, how did you find tuning and living with it since? From the outside it looks like a simple method of ditching the AFM. Surprised so many have trouble tuning, especially with closed loop wideband! Understandable if you have never tuned anything yourself but if a "pro" tuner cant figure that out I certainly wouldnt trust them with anything else!

    Leave a comment:


  • stevesingo
    replied
    Who talks +20%? The article I linked does not state that, but the improvements are clear on otherwise stock Evo2/3 engines.

    THe 2.5 made +6% hp & +4% torque over a programmed EPROM without going over 7500rpm and the Evo 2 made +10% hp at a lower rpm (7093rpm vs 7216rpm) and +12% torque aleit at 800rpm more.

    There are several factors which limit the output of production engines, emissions and noise being the largest. That is why very few mad +100bhp/litre prior to VVT/L being developed.

    You are clearly entrenched in your view, despite the evidence to the contrary.

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  • france320isco
    replied
    Originally posted by stevesingo View Post

    That depends. From the air filter intake pipe to the valve/seat is a long way with changes in shape and cross section. A test of pressure drop at different points would define where the largest pressure drop is. On a 2.0 S14, with same valve size, lift andTBs accumulator as a 2.3 engine, the AFM may not be the greatest cause of pressure drop. The same AFM is used on S14 engines from 195ps to 220ps. Maybe on a 220ps engine the AFM has a bigger pressure loss than a 2.0 S14.

    I'm sure there are lots of examples where the intake is causing a pressure drop.



    This is not only untrue, but also the wrong yardstick for measuring the potential of an NA engine. Firstly, there are NA engines that have made 300hp/lt, so that indicates 100hp/lt limit is incorrect. What is a limit is torque/litre or Brake Mean Effective Pressure (BMEP). The best that can be achieved is around 95blft/litre or BMEP of 16Bar on gasoline. We are talking highly developed motorsport engines (MotoGP/pre 2014 F1). Realistically, on a road based engine 85lbft/lt or 14.5Bar BMEP is what can be expected as a limit without serious development which usually results from a race series development program.

    As power is a function of torque and rpm, it is easy to see why 100bh/lt is easy to best. Take an engine with 85blft litre at 6000 rpm, we have 97hp/lt. Take it to 12000rpm we have 194hp/lt. An extreme case, but the point is clear.



    Clearly not, but faced with a set of compromises (emissions legislation, noise, available technology at the time, cost, etc) which the after market does not have to consider.

    In 1985/86, when the E30M3 was being developed, Bosch Motronic was one of the very few engine management systems available to the OEMs with the provision for lambda control - therefore needing mass air flow measurement - required for impending catalytic converter legislation, it was state of the art at that time. Hot flim MAF was introduced in '88, but does not work well with 4 cylinder TB equipped engines due to induction pulse waves. MAP based load measurement only became available in the late 80s, early 90s. A/N control strategy does not give sufficient control of AFR for narrow band WBO2 closed loop control.

    Therefore, BMW MS were stuck with it. As time progressed and 195PS(KAT)200PS changed to 215PS(KAT)220ps BMW did not change engine management, even with 238PS(KAT) Sport Evo, although the sport Evo had a larger AFM so it could be assumed that the original size was too small for 238PS. It is worth remembering that the evolution of the S14 power output was not driven by customer demand. Homologation of specific parts for racing purposes drove the new models. Did the Evo2 need a 264deg cam for homologation? No, but BMW could hardly charge '000 Euro extra for a model with negligible extra power. BMW MS did not need to change the EMS from Motronic 1.1 as it was not required for homologation as would have been a significant extra development cost which would not have been recouped through selling 500/600 units.

    Did BMW MS ned to change the air accumulator from 195PS to 238PS? No. Why? It was not a homologated part and would have been costly. They did change the air filter intake trumpet from an aluminium item with a 90deg bend to a straight plastic tube, presumably because there was a pressure drop too great for 220PS, but equally importantly, it was low development cost and probably lower cost to produce also.



    It is likely that back to back, stock vs aftermarket engine management with A/N breathing through something like the rongineer airbox, http://www.rongineer.com/Photos/m3_airbox_installed.jpg on a 2.0 wouln not gain much. On a 2.3 215ps engine, maybe. On my 2.5, it certainly did gain power and torque, as it did here http://www.rongineer.com/straightsix_article1.html

    But, like I have stated previously. most adopters of aftermarket engine management with A/N use it to facilitate other modifications, at least a CF GrpA type airbox. In such cases of just the CF airbox there is a wealth of evidence that there is significant improvements in power and torque even with an intake runner length which is not designed to complement stock cams and operating rpm in the <8000rpm range.
    I never knew a street car developing, stock, the famous 100hp/litre (if you don't believe that limit, google it). If there is any, without VVT or similar, like s14, they are not so common (especially from '80s/'90s) which means, again, that all the chocking thing is smoke (technically speaking). The A-N somethimes reduce performances too.
    If you get things like DTM or better, then, you can expect improvements.

    Numbers is +20% power on a 2.5cc, don't know @ what rpms.

    "Probably", "Maybe", is not in my engines dictionary. Nice story though.

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  • jimmy p.
    replied
    Originally posted by france320isco View Post
    Sorry, but this is obviously not true.
    It's a common mistake. We call bottlenecks, in any engine, the valve / valve seat maximum play at the highest lift.
    Have you driven back to back an S14 powered car of any description with no other changes than AFM to A/N?
    If you have there is no way you can say that.

    A to B it has consistently been the largest single real world driving performance improvement of anything I have done to any S14 in my 25 years of owning E30M3s.
    No other single modification has come close to providing than much change in the driving dynamics of that engine.
    When I purchased my S14 powered Cabrio it had an AFM on it, otherwise stock 2.3 except for a LW Flywheel.
    I drove it for the first time and then took it into my garage an immediatley put an A/n kit onto it, Rolled it back out of the garage and took it for a ride and the difference was night and day.

    This is about as real world as it gets.
    Below is a link to an old video, the quality isnt great but the takeaway for the purposes of this thread is watch the straight line acceleration differences.
    Both of these E30M3s in the video were identical in prep, specifically made to be identical by the two owners to provide the most fun factor on track together.
    Both drivers of equal skill level.
    The only difference, the camera car was on an AFM and the other car had A/n (primitive chip based A/n at that time).
    Watch the performance difference on the straights.

    https://www.youtube.com/watch?v=COsBireCSGg

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