NefMoto

Does anyone know the best way to complete this table . Now I am guessing it's worked out from the compressor map for each turbo, and assume it takes into consideration surge limits etc but I can t find any hard facts on how the figures are worked out. I have one for my hybrid is was given which works well but nothing on how the figures were come by.

The instructions for the calibrator to define KFLDHBN are given in funktionsrahmen module LDRLMS 3.1000. Reviewing my translation doesn't make it abundantly clear what is done, other than making reference to the turbocharger compressor map as you say:

"KFLDHBN: Firstly, in the compressor performance map, acquire the regular full load line at the speed sample points of KFLDHBN as well as the maximum pressure ratio line (due to the surge limit, maximum turbocharger-speed or prohibited areas of poor efficiency) to define the operational limit.
Then continue on the altitude gradients from the normal full load line starting at any engine speed, up to an operating limit.
The volumetric flow rate increases with increasing altitude (decreasing ambient pressure) and the pressure ratio with 1013/ambient pressure.
This new intersection then defines the maximum pressure ratio for KFLDHBN at the respective engine speed."

My understanding is that this map is to limit turbocharger performance at higher intake air temperatures and altitude when the charge density will be lower.

Sorry that this probably doesn't help you much. I don't know whether tuners fiddle much with this map. Looking at the BAM file, there isn't much difference in the ratio until you start getting above 70°C IAT. I don't think it's worth too much thought for UK temperatures and altitudes. :-\

TTQS

To be honest, I just log ldrlts_w (from KFLDHBN) and ensure it remains slightly above rlmxko_w. I am tuning at sea level, so it doesn't limit load at sea level, but is available should I need it at altitude.

Critical part on this one is turbo speed and compressor outlet temperature (because for example some connection hoses can't handle more heat permanently). All cars that are used to create the calibration have turbo speed and temperature sensors and are driven under various conditions to find the PR that keeps thinks into these defined limits. This is the intention for the function. You have to make it fit your needs on a modified vehicle (I ignore the temperature thing and just use the compressor map to make a safety net for overspeeding).

is the map purely PR limitation?

If it helps here is the stock KLFDHBH from my Original tune and also the KLFDHBN from the hybrid I have been running. Its a 2283 compressor wheel so obviously capable of far more than the stock wheel. I'm thinking its just one of those maps that's either correct or not and not something that needs tweaking, It would be helpfuly though If there was someway of working out how these figures where gotten to as I have a 2280 series wheel that I would like to map and just want to make sure that the map is correct.

the rs4 map should be used for any k04 apb engine...

Yes.

To calibrate it properly you have to either equipe your turbocharger with a speed sensor and drive up the mountains or simply take the compressor map, do some calculations and enter the values to have a good guess.

Note that if you are running past the MAP limit, all of this is academic.

i used to have this maxed out.  however i put on the rs4 table attached here.  i boost 23-24 psi on occasion with k04's, although right now i have a parallel mbc pegged at 20psi for some fuel fine-tuning.  this table has never bothered me nor got in the way since switching to the rs4 map intended for k04's written correctly onto the s4-axis table in the s4 m-box.

agreed... more over in my car w/ much larger turbos and a base boost pressure of 22psi minimum (@ 0% WGDC) which means you're operating over the MAP limit anyway like Nye says, that table is useless to my car or any other GT style car.

stage 0 - 2, stick to stock M-box or M-box multiplied.
stage 3, stick to the table i uploaded.
stage 3+, like nyet/nvr said, not functional.

Depends on where you live. You have to think in absolute values, because that's what all the ECU calculations are based on. In Denver for example with a AMP of ~830mbar the MAP limit of 2559mbar is a PR of 3,1:1 ~ 30psi boost ;)
But you are right that it's useless if the WG cracking pressure is over the absolute limit anyway.

So just to revive this old topic because i've been trying to dial KFLDHBN in I wonder why shouldn't I just use the exact same KFLDHBN from the RS4 including the rpm and temperature axis (which is different as well)?
Also I've managed to take a peek into a RS4 MTM stage 1 file and it seems they have modified KFLDHBN a bit to allow elevated boost as well.

The difference is shown here: http://nerd.hu/kfldhbn.txt

So I wonder what are you guys have been experimenting with in the past couple of months?

Thanks

I personally disable it and control everything with LDRXN ;)

i have been running kfldhbn disabled...and so far so good, but lately i have been thinking of tweaking it

I really takes almost no time or effort to preserve this function and not have any intervention during normal operation.

I agree. It is not a terribly complex map.

If you have to 0xFF it, I shudder to ponder your understanding of more ... subtle.. maps

So this is what I've been experimenting with (KFLDHBN based on the RS4 one with the RPM axis changed).

nyet, i originally was trying to make use it, but ended up disabling it to see if it was the cause of my issues, and it was, at the time i had very poor datalogging capabilities, but now that i actually can log, i will be making use of it......

Could you please explain how you disabled KFLDHBN ?

Thanks in advance!

Set whole table to 3.09

So as far as I understood LDRXN has higher priority than KFLDHBN, yes?

There is no such thing as "priority"

If you have KFLDHBN FF'd, god help you when you venture into a higher elevation. At 10,000 feet your car will be requesting 30psi to try to hit requested load.

It's unreal sealevel for me, I don't live in mountains :)
But any case I've understood you, thanks!

Guys please clarify: if LDRXN=160 and KFLDHN=2.9 - result boost will be limited by LDRXN or by KFLDHN?

ME7 works on requested load. At altitude it takes more boost to produce the same load. At sealevel 19psi might produce 170 load, whereas at 5000ft it may take 25psi. KFLDHBN limits requested load to prevent excessive turbine shaft speeds.

In short, requested boost is limited by both LDRXN and KFLDHBN.

But also look at a compressor map for your turbo, find the 2.9 compressor ratio and see if its even on the map or any where you want to run a turbo! Especially at sea level! I can almost certainly say if you run a 2.9 you will either be surging or so far outside the compressor efficiency range it will have probably over speed its self already long before 2.9 is reached.

At sea level surge will almost occur before over speeding exists of the shaft. If you encounter changing the compressor wheel is an option. If you maxed your table then ldrxn and surging is the limit but you'll hear that .

Thanks a lot guys for your assistance!
I've understood the map!

I plan to run KFLDHBN as a sole load limiter map in my tune, this is with tial 770s, 4bar map and 5120 hack naturally. This way I should always run at the psi I want, instead at what car wants.

Would it not be easier just to max kfldbhn and ldrxn and tune boost via kfldrl ? ECU might not be actually controlling boost but a bit of work and tunning of klfdrl can't be any harder than setting up kfldbhn. You can set exactly the boost you want when you want.

You're missing the point. Assuming here that you mention KFLDRL as you want to run more than 22.5psi below which KFLDRL doesn't have to be used to limit WGDC in max load.

KFLDRL can be used to limit wastegate activity to reach certain WGDC at any given load and RPMs... however it has several limitations, most notably:

1) doesn't take under consideration intake temps so you will run the same WGDC, with different boost levels, regardless of time of year.
2) doesn't allow PID controller to do its work and use high WGDC when needed, like coming into boost from part throttle to full throttle at higher RPMs.

With properly modified ECU, with 5120 hack and 4 bar map installed in the car, you can have stock-like-looking KFLDRL (with 95 in last column etc) and let the ECU do the job of moderating boost via PID controller regardless of boost/load level.

Controlling boost with KFLDRL is a thing of the past imo :)

But I dont see why you want to run one specific boost pressure all year around either, since it will fill the engine differently with different IAT's. Since the code is there to fill the engine the same amount, regardless of IAT?

Let me clarify.

I want to limit max load via compression pressure ratio not a load number which I don't know what it will translate into as far as pressures go. I want to run a boost level which I know is safe for my car and be able to tell when something is off since I am missing 1 or few PSIs from logs/gauge. With load limiter from other maps, the pressures are dependent on timing etc.

The KFLDHBN will still ramp up like stock one in regards to IATs. It will just have the pressure ratio I am looking for in my particular application. At least I hope it will work that way, we'll see.

I have KFLDHBN maxxed at 4 and it's now the limit of my boost I can run lol. It won't request more than 40psi :-)

"some" problem lol.

Haha first world problem right?  ;)