S50B32 AN tuning vs stock HFM and Siemens

[M3 Euro LTW]

Rather than post this in the thread on MZ3 conversion thread where it just came up and AN was recently mentioned... I thought I'd put up a new topic.

Over the years, many companies have come out with option to change the S50B30 or S50B32 from their stock arrangement to a system that is AN in nature.

Deleting the HFM and going to AN does not intrisically insure that you improve performance.

Many people are mistaken in believing that AN is intrinsically better than the factory system using HFM, and though I can not prove it, I suspect that this is for two reasons. First, BMW won an incredible number of S14 based races with AN on their engines, and this created a lot of buzz. (pun intended for the S14 crowd). Going to AN required state of the art computers, which they used, as well as getting rid of the restrictive MAF...which even at full throttle had a flapper door. Sliding throttle plates got rid of even MORE restriction. Second, people believe that the factories HFM for our motors is restrictive. (if anyone has any proof that this is the case below 400 HP at the crank, I'd love to see it!)

Truth is that for measuring load (which is what AN does) using the TP and the rpm is a very, very crude manner compared to the modern HFM. Unless you've built your engine with substantial cams, valve work, compression, as well as exhaust work, one is not likely to exheed the flow capability of the stock HFM we have on our motors.... for that reason, a proper re-flash of the DME which continues to read the HFM is FAR more likely to give a good streetable engine that will perform regardless of altitude, air temperature, pressure and humidity. So...you can put AN on an engine, and actually end up with "less" in some ways.

For the S50B32 however, there are limited places to do a reflash for many customers. However, a proper re-flash which retains the hfm is actually likely to result in much smoother operation, more power, and certainly more flexibility for different conditions.

I'd love for someone to clean up my comments or put them in better motorsport terms if they like, I won't be offended. I am repeating a lot of "things I've heard", as they say, and I may not have put it quite clearly.

But before everyone runs out and rechips their cars or reflashes them with minimal changes done to compression, cams, valves, compression, exhaust... think twice.

[GazM3]

interesting topic.

I actually ran my 3.2lt without the maf (substituted with a 90mmPVC pipe in place of the maf, with original filter ect)on thier inbuilt alphaN setup, and other than running rich there definetly felt like it was free, the intake note was definetly sharper, but it used shit loads more fuel and was not as smooth below about 4000rpm.

I guess why ppl are interested is from the M3CSL (e46) which runs this setup, giving freedom to use alternate intake plenums ect. Give me a month or so and ill get the alphaN tune mapped on a dyno in real time, to see if there is the following.
a/ any benifit power/torque wise to do so.
b/ power is more consistant
c/ throttle response is any better.

Im not saying its better way to go for the S50B32, but my curiosity has got the better of me and i have the oppurtunity to do this "development" at reasonable cost.

Most ppl who ive had contact with who have gone AlphaN route with the S50B30, and the S14 have raved about the modification

[odortiz]

the e46 m3csl does not run alpha-n. it measures load using a MAP sensor. which means there sould also be a barometric pressure sensor somewhere in the car for comparison by the ecu.

on another note, alex, what kind of compression can you realistically use when using the 55 Cel. thermostat offered by motorsport? street use/street gas.

[liquidtension]

ps: systems like megasquirt dont use an independant barometric sensor for correction, when u turn the car off then on, it measures the atmospheric pressure to compare. It is upgradable by adding another MAP sensor for "real-time barometric correction"

[M3 Euro LTW]

GAZM3.

If you can do this affordably, the REAL testing should be the following to make sure you're really doing an appropriate A/B comparison.

First, you should re-map YOUR particular engine for the gas you use to maximize its performance as it is. Simply doing a re-map to maximize it gives you a real baseline of a maximized tune. You can expect some gains, perhaps only 1-3%, but those are real numbers.

THEN put on your AN set up of strictly intake plenum and HFM delete. Maximize that tuning.

Without doing a remap of stock, you'd be including an extra 1-3% that is not due to the AN set up at all....and could have been realized without going to AN first.

I suspect, but can not prove, that simply deleting HFM and putting on even a good intake is not going to net much more than 7 HP...and that is from hard core data on our end. (S54)

Dave, contact me, your doors can be shipped soon!

Alex.

[Thewiseguy]

I would be really interested in finding out about this. If anyone with an Alpha N set up is going to the dyno soon, I would ask if you could run the dyno with the correctly tuned software and no HFM, then simply install the HFM without pluggin it up. I want to see if there is indeed any difference from the airflow being restricted.

[morerevsm3]

I would be really interested in finding out about this. If anyone with an Alpha N set up is going to the dyno soon, I would ask if you could run the dyno with the correctly tuned software and no HFM, then simply install the HFM without pluggin it up. I want to see if there is indeed any difference from the airflow being restricted.
I did that with my S50 B30 with original plenum, did a couple of power runs which netted 191rwkw, then removed the boot from plenum ( and disconnected MAF) and did another 2 power runs, it then netted 199.6rwkw, but was dangerously lean...

with proper plenum and alpha n chips, throttle response is much crisper, it only netted 192rwkw, but at 11.1:1 AFR, so it will improve with a little tweaking, it should hit 200rwkw

[GazM3]

we will do the dyno before /after. If i can get 3% would be good(say 10rwhp), but IMO there is no benifit if u only get say 3% at the topend and even lose some in the midrange, its gotta gain all the way thou. I guess time will tell, hence is why we do testing and development to find answers to these questions.

[liquidtension]

I would be really interested in finding out about this. If anyone with an Alpha N set up is going to the dyno soon, I would ask if you could run the dyno with the correctly tuned software and no HFM, then simply install the HFM without pluggin it up. I want to see if there is indeed any difference from the airflow being restricted.


dude i've already done that 5months ago.. dyno run with MAF and another without the MAF search the eurospec forum for my dyno run..

also i did some tests datalogging air fuel ratios 3rd and 4th gear with the MAF installed and with it removed.. the figures are uploaded as well for both runs..


on the dyno i gained ~5-10bhp with the MAF unplugged, and on the air fuel ratio i cant remember but there was a difference 0.5 (air/fuel not lambda)
cant remember.. i only remember at idle with the MAF unplugged it went from 14.6:1 to 11.5:1
cheers!
eric

[BSH]

liquidtension, I can't find your dyno thread.

[liquidtension]

3rd and 4th with MAF:

http://www.geocities.com/lte112/3rd4th.JPG


3rd 4th without MAF:

http://www.geocities.com/lte112/3rd4thwoutmaf.JPG

Dyno without MAF: (however the hp numbers are wrong, the dyno operator didnt know how to get the right rpm signal for the dyno to calculate hp)
i guess it's not much of use..

http://img224.imageshack.us/img224/1039/img0041oo5.jpg

[M3 Euro LTW]

the e46 m3csl does not run alpha-n. it measures load using a MAP sensor. which means there sould also be a barometric pressure sensor somewhere in the car for comparison by the ecu.

on another note, alex, what kind of compression can you realistically use when using the 55 Cel. thermostat offered by motorsport? street use/street gas.

Good point, and now more commonly known too. Without knowing of course the actual code, it is hard to know really whether they're completely running it on MAP, or factoring TPS in a bit, or, the reverse, or whether there are hybrid 3D maps....who knows?

However, interestingly enough, looking at the Bosch website for many of their MAF sensors, some of them incorporate a small cap of metal that was welded shut under as close to absolute vacuum as they could arrange, and that provides a baseline for them. I've not yet found the Bosch part number for the MAF that the CSL uses to study the specs...but I'd like to!

Second, missed your question. You may know more than I do in terms of how the thermostat might limit compression if one were in place. In direct answer to your question, I have removed my thermostat completely, pulled the impeller and bearing apparatus, welded it shut, but tapped it for future use of a temp probe there. I run an EWP system, and have for years.

How that might affect the siemens unit I have had reflashed for AN, I have no idea.

Alex.

[JamesM3M5]

The ECU may also take a reference barometric pressure reading before starting the car.

Is the MAP sensor in the plenum or after the throttles in the vacuum manifold? In all likelyhood, the CSL ECU probably doesn't put much emphasis on reading the MAP sensor. In all the multi-throttle engines we've done with aftermarket ECUs, the MAP signal is exceptionally unstable at idle and part throttle, and they build poor vacuum at idle. The variable cam timing helps that significantly, but you won't get a stable or high vacuum reading like you would with a single-throttle and common manifold engine. I have to damp the vacuum vibrations with a tiny choke and small chamber, a few cubic inches.

[M3 Euro LTW]

The ECU may also take a reference barometric pressure reading before starting the car.

Is the MAP sensor in the plenum or after the throttles in the vacuum manifold? In all likelyhood, the CSL ECU probably doesn't put much emphasis on reading the MAP sensor. In all the multi-throttle engines we've done with aftermarket ECUs, the MAP signal is exceptionally unstable at idle and part throttle, and they build poor vacuum at idle. The variable cam timing helps that significantly, but you won't get a stable or high vacuum reading like you would with a single-throttle and common manifold engine. I have to damp the vacuum vibrations with a tiny choke and small chamber, a few cubic inches.

I think that instability is why so many people are simply tuning with TPS on the engines, and just adding some barometric compensation to account for days/location with different environements than the day/place it was dyno tuned.

On the CSL the MAP sensor is plugged into the vacuum manifold. Different part number than the stock S54 manifold. Realoem shows it. The MAP sensor installs in the hard line that leads to the brake booster.

MSS54 seems to have a barometric sensor on the dme board as well

In theory it would be nice to tune these engines with MAP as the secondary axis to rpm, but TPS seems to be the more common route, and it probably has to do with the instability of signal (this isn't a big american V8 with 4 barrel and huge manifold!). It would be fascinating to know just how much the native code for the CSL relies on the MAP senor vs the TPS for determining the fuel and timing....

[S50B30T]

In all the multi-throttle engines we've done with aftermarket ECUs, the MAP signal is exceptionally unstable at idle and part throttle, and they build poor vacuum at idle.


James,


What brand after market ECU's and on what engine's did you find the unstable vacuum signal you're referring to? Also were these engines running standard cams?


I tuned my S50B30 in TPS vs MAP vs RPM with my Autronic SM4. I initially tuned it in N/A form and drove it around for 3 months before turbocharged it and retuning it to suit so I do have experience tuning a multiple throttle body engines in both N/A and FI form.


At idle the map signal is very stable as well as at part throttle. The only time I found the map signal to not be stable is between 12-14% throttle and 2,000-3,000rpm where the map signal fluctuates between 3 inch of vacuum and 0 vacuum. On the fuel delivery side of things this is not a problem if you know what your doing with the SM4 and even though there is a slight fluctuation of vacuum the target A/F maintains steady, the other thing I had to be careful of was to make sure the ignition timing would not fluctuate as the vacuum signal would fluctuate but again, this can be “tuned” out with an experienced tuner that knows how to use the software to your advantage.


Alex,


If the car is a street car you will have unstable fueling if tuning in TPS vs RPM mode only on multiple throttle bodied engines. One example is when the engine is at idle and if the car is tuned in TPS vs RPM then the injection on time is set as a given due to the ECU looking at the 0% throttle position only at idle. Once the cars A/C is tuned on or the head lights are tuned on at idle the engine will run leaner due to the added load on the engine and the engine may stall. This is where the MAP signal comes into play (when tuned in TPS vs MAP vs RPM) as the vacuum signal is reduced at idle when the A/C or lights are turned on, the ECU then can add the correct amount of fuel to the TPS figure using the MAP signal to maintain the correct target A/F.

[m3ltw98]

I run a baro sensor on my car w/ the motec and it runs beautifully at all RPM ranges and throttle positions. Here is Neels explanation for the use of baro on a NA ITB motor. Neel is the owner of apexspeedtech.com and knows his stuff. Hope it helps a bit. Figured it was relevant as it discusses baro (alpha-N) compared to MAP


That is correct, just run a BARO sensor. And you DON'T want manifold vacuum if you are running Baro, all you want is AIRBOX PRESSURE to account for any ram air or pressure drop from a filter.

The 3 most popular ways to calculate amount of air going into your engine are:

1. Throttle Position (TPS)
2. Manifold Pressure (MAP)
3. Mass Airflow (MAF)

TPS is often the most consistent to tune on a naturally aspirated (NA) engine, which is why the use is so common. Its a fairly good assumption on an NA motor that for a given throttle opening and constant speed, the airflow into your engine is constant. Therefore, you can map a motor based on throttle position and RPM and expect to get pretty good results. The downside is that you have to MAP your motor. You don't have any guidelines for determining how much air passes into your engine versus throttle position. So with a TPS mapped engine, your fueling table must be determined by running the engine can calibrating fuel and spark versus throttle position.

MAP calculates the amount of air based on air pressure in the manifold. This is a bit more accurate because as the engine wears or things like intake and exhaust change, the relationship between MAP and load will change too. In essence, MAP is more tolerant of changes to an engine as it wears or modification are made.

MAF actually directly determines how much air is going into your motor. There's no derivation here - for a properly designed system, nothing beats it.

So why do we advocate the LEAST accurate method when dealing with NA cars? Well, its all about the "real world."

On a naturally aspirated vehicle, even with good ram air, the MAP is not much greater than 15psi. And at idle, if you have a conservative camshaft so overlap is minimized, your minimum is rarely less than 5psi. So all your fueling is determined in 10psi of range. Air is a compressible fluid. So the pressure can very based on where its being read. Furthermore, it experiences resonance - you can have situations where the pressure rises and falls rapidly as pressure waves travel through the manifold. Plus, since air has intertia, the response time of the pressure can have some lag. All this can easily lead to 1-2psi in error or fluctuation which is 10-20% of your range! So in reality, on an NA motor, MAP based tuning is often MORE inaccurate because the pressure being read is not consistent, and attempts to make is so just dampens the response. The less manifold volume and the more aggressive your camshafts are, the worse this becomes. Multiple throttle bodied motors can be especially bad.

On a turbo motor, you are often running 30psi (absolute) of manifold pressure or more. This helps with resolution issues. Plus, the motor runs positive manifold pressure quite often, which decreases response time and helps naturally dampen resonances. Also, for turbo applications, TPS is NOT representative of airflow, since you can have different levels of boost for different throttle positions. More often than not, we fuel force-induction motors based on manifold pressure.

MAF is very accurate, but has limitations that make it best used in OEM settings. First of all, the air going past the sensor MUST be non-turbulent. This means it has to be in a relatively straight section of pipe. Also, often times you'll see grates or screens to make sure the air is going past the sensor straight. If the air resonates, readings will not be accurate. Also, 100% of all intake air has to go past the sensor. Often times, this means you have inlet restrictions involved. Finally, remember there's a "transport delay" meaning that the air mass takes time to travel into the engine, so you don't get great response always either (a problem shared with MAP.) Any air leaks or a boost hose popping of will ruin your fueling. So in the end, MAF doesn't work so well for the aftermarket.

Here are my guidelines:

1. Bone stock engine - use the MAF.
2. Naturally aspirated cars with non-stock intake systems - TPS based.
3. Forced induction cars other than completely stock - MAP based.

Now there's a few hybrid strategies out there that use both, and a number of OEM NA engines (Honda, BMW V8) that use MAP for load. So none of this is cast in stone.

I hope this clears things up.

-Neel

[S50B30T]

That is correct, just run a BARO sensor. And you DON'T want manifold vacuum if you are running Baro, all you want is AIRBOX PRESSURE to account for any ram air or pressure drop from a filter.

The 3 most popular ways to calculate amount of air going into your engine are:

1. Throttle Position (TPS)
2. Manifold Pressure (MAP)
3. Mass Airflow (MAF)



M3ltw98,


Please understand that I am sharing my experience here (15 years tuning Autronic/Motec systems) and NOT trying to start an argument nor slamming what others are saying...... :)


Though I agree with almost everything Neel has said, I am confused on his take about the Baro sensors use when trying to measure AIR BOX PRESSURE. I understand the reasoning behind it all however for this to work wouldn't the Baro sensor or at least the Baro sensors input have to be directly connected to the Air Box itself to be able to measure any positive pressure within the air box at high road speeds?


If so, there could be a few short falls, the first being that on the cars initial tune, it is unlikely that you will be able to generate any positive pressure in the air box while the car sits static on a chassis dyno. No doubt you could simply put in a guess to the required added fuel based on any possible positive pressure within the air box and then take some data logs from the track and re-adjust to suit.


The other short fall that may arise is that even though there may be a positive pressure within the air box at elevated road speeds on the track, this does not necessarily mean that the same level of positive pressure will be seen between the throttle butterfly and the intake valve, this will be dependant on the “pressure drop” between the air box itself and the engines plenum. The design and therefore the air flow path between the air box and engine plenum (number of tight bends, internal surface finish of the pipe work etc) can generate some form of pressure drop. If there is any real way of measuring any possible positive pressure that the engine may see, it should be measure between the throttle butterfly and intake valve, in affect, a MAP sensor.


As Neel had pointed out, when tuning ITB engines the best form is TPS followed by MAP (agreed). In my case the ECU i use can combine the best of both of these and this is exactly why I choose to tune in TPS vs MAP vs RPM.


Another case where this method of tuning is advantages over TPS vs RPM only, is not only on the fuel delivery side of things but also on ignition timing. An example that comes to mind was when driving over a speed bump. I had left the car in second gear without depressing the clutch, when tuned in TPS vs RPM the engine would ping when the engine rpm was at 1,100rpm and 5% throttle when going over the speed hump however on a flat bit of road at the same 1,100rpm and 5% throttle there was no pinging. When the car was tuned in TPS vs MAP vs RPM this was immediately fixed. What was happening was when going over the speed hump in second gear at 1,100rpm and 5% throttle, the engine was pulling 5 inch of vacuum where as when the SAME throttle position and rpm was held on a flat piece of road the engine would pull 12 inch of vacuum. When the engine was re-tuned in TPS vs MAP vs RPM the ECU can then have a far better means of knowing when the engine is REALLY under more load (TPS vs MAP) then what a simple throttle position opening can indicate.....


This is REAL WORLD tuning/experience.

[m3ltw98]

No hostility taken. I think when Neel was typing that, he was rushing and got things mixed up. I repeatedly asked him if my baro sensor should have a line to my CSL airbox and he always said no. Even with the ram-air effect, it is not enough positive pressure to tune accurately. I always had a MAP to a vacuum source with my AEM/Tec3r before moving to motec and the part throttle always sucked and would change from day to day. I am in no way trying to be an expert in this matter. Just trying to pass along/decipher what Neel has been telling me about his experience with tuning ITB motors such as the S54/S50B32 etc.