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So how do some dataloggers calculate load?
load is how hard the engine is working and since we are dealing with fuel injected cars its going to come from a percentage of how much air is being taken in/ how much air can be taken in.

SO

its a percentage of how much air can be taken in divided by the maximum amount of air your car(setup) CAN take in.

If you are dealing with the stock MAS and it reads in Hz however many hz divided by the maximum reading your sensor can take in.

FYI, its easy to peg the stock MAS hz reading which is also why the stock boost guage jumps to 14 psi (max load), with very little effort. I guess you can use it as a reference point in that aspect (percentage).

EX.

Max Hz reading with your given setup at ____ psi peak is 2500 Hz.

If you are measuring 2000 Hz in a 3rd gear pull up a slight incline. Your load is 2000/2500 x 100 = 80 % load .

Why is this number so important to you anyways?

Once upon a time when I was watching topgear and the Veyron's hp guage, I thought to myself it wouldn't be hard to dyno your car, find out the maximum hp your setup makes and change the stock boost guage to read hp (well sort of).

IDK I thought it would be cool.
 

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load is how hard the engine is working and since we are dealing with fuel injected cars its going to come from a percentage of how much air is being taken in/ how much air can be taken in.
No, it's not.

The fuel and timing maps (among other things) use a direct measure of air volume and air mass from the mass air sensor. It doesn't matter what size turbos or what displacement engine or anything else is behind that MAF. It is how much air is flowing through the MAF sensor. Period.

This percentage based load thing is a leftover from before the Evo guys properly understood their code. I've been reading through the last 5 years of posts on 4 different boards. It is flat out WRONG, but since it's so entrenched and people are so used to it, it's stuck. It's just like the thing we deal with for so-called "MR" gears and the mythical "JDM 13Gs". The MAF sensor doesn't stop reading at 1603hz either. Bad info got out there, and now it's impossible to change it.

The real value is units of air per second, which is derived from the frequency of each crank rotation. The Stealth Technical manual along with several other sources says it clear as day.
 

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No, it's not.

The fuel and timing maps (among other things) use a direct measure of air volume and air mass from the mass air sensor. It doesn't matter what size turbos or what displacement engine or anything else is behind that MAF. It is how much air is flowing through the MAF sensor. Period.

This percentage based load thing is a leftover from before the Evo guys properly understood their code. I've been reading through the last 5 years of posts on 4 different boards. It is flat out WRONG, but since it's so entrenched and people are so used to it, it's stuck. It's just like the thing we deal with for so-called "MR" gears and the mythical "JDM 13Gs".

The real value is units of air per second, which is derived from the frequency of each crank rotation. The Stealth Technical manual along with several other sources says it clear as day.
:) I wonder how anyone would think the measurement from the MAS (aka Mass Air Sensor) would give any sort of info towards that?

Whatever, its the stock ECU's interpretation of load based on that info from the MAS. Thats what the stock guage is giving you. Do I use it? NO, not sinse I put a real Boost guage in there and could monitor my o2 signal, could I if I were anal and just wanted a percentage at any given moment for various driving scenarios? Yes.

Based on the amount of air that can be measured versus what is measured at a given moment you get a percentage of what your setup is capable of, or load percentage. 50% of what setup A (tdo5 evo 3's) is capable of maybe more than 100% of what setup B (9b's) is capable of.

Regardless you still have a percentage of a given setup, and its all coming from the MAS on our FI cars. X amount of air requires Y amount of fuel to hit your targeted A/F ratios. We alter that signal with A/F controllers but the signal from the MAS is the same. Well for those who haven't altered there stock MAS.

The MAF sensor doesn't stop reading at 1603hz either. Bad info got out there, and now it's impossible to change it.
That's probably the highest number reported by whatever logger. What are you using to log? I forget the exact number but IIRC my scanmaster pegs at 16xx when looking at the MAS sensor on various pulls. With 9b's and with 13t's it didn't take anything to hit that number either (typically before 4k rpms). I mean of course you realise there has to be more considering max hp is somewheere around 6-7k so it definitely has to be reading more to get there.

Kinda why I stopped paying so much attention to it, and religated it to just the level of something cool to look at every now and then (stock guage). Then the idea for a HP guage came to me after watching the Veyron vids. Not hard to get some different plates made for the stock guage with whatever you want written on there.
 

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I wonder how anyone would think the measurement from the MAS (aka Mass Air Sensor) would give any sort of info towards that?
Oh, I don't know. Maybe because I've disassembled the actual operating code in the ECU that calculates those values? Because the disassembly of our code matches that of the DSMs and the Evos, and their guys all agree that it's an airflow calc? But WTF do I know?

Based on the amount of air that can be measured versus what is measured at a given moment you get a percentage of what your setup is capable of, or load percentage. 50% of what setup A (tdo5 evo 3's) is capable of maybe more than 100% of what setup B (9b's) is capable of.
There is not one parameter anywhere in the ECU that tells it that it's running a 3L or a 3.8L or a 7L engine. There is nothing that specifies a turbo size. The only reason it even knows or cares how many cylinders the car has is because it needs to schedule injector and coil activation. There is not one single math function anywhere in the code that compares current airflow to some theoretical maximum.

There is no possible way it can calculate a load based percentage without knowing the displacement of the engine and there's no way you can do it without the current vs maximum airflow calc...which doesn't exist. If you want to argue that, please bring some FACTS to the table instead of your speculation.

As for what I'm logging, I've modified my logging tables to output the full, unclipped 2-byte MAF Hz value to EvoScan. I've seen up to 2300hz on my logger. Using that, some technical specs for the MAF and some other calculations that have absolutely nothing to do with percentages or 'load', I've been able to calculate the approximate CFM intake of the engine at any given RPM/airflow value. I've checked it against the compressor flow charts, and it's well within range of what my setup should flow at those intervals.
 

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Oh, I don't know. Maybe because I've disassembled the actual operating code in the ECU that calculates those values? Because the disassembly of our code matches that of the DSMs and the Evos, and their guys all agree that it's an airflow calc? But WTF do I know?
Thats what I was saying ;) . Its not surprising that the ecu is calculating MASS of air from the Mass Airflow Sensor. The simplicity comes in that if you have that same signal you can do whatever you want with it. You can even represent it as LOAD for a engine once you have found the given max of your setup and have the appropriate MAS signal for it, you have something to compare against.

There is not one parameter anywhere in the ECU that tells it that it's running a 3L or a 3.8L or a 7L engine. There is nothing that specifies a turbo size. The only reason it even knows or cares how many cylinders the car has is because it needs to schedule injector and coil activation. There is not one single math function anywhere in the code that compares current airflow to some theoretical maximum.
Yep, remember me saying that 50% load for one setup maybe more than max what another setup is capable of?

The calculation is done by you, not the ECU. Its just a airflow signal what you want to do with it is up to you. You CAN use it to come up with a load percentage once you found out what your max is.

There is no possible way it can calculate a load based percentage without knowing the displacement of the engine and there's no way you can do it without the current vs maximum airflow calc...which doesn't exist. If you want to argue that, please bring some FACTS to the table instead of your speculation.
No need for me to speculate. You get it now. I even mentioned a dyno for my little makeshift hp guage so I would have a reference as to what to put on the guage.

As for what I'm logging, I've modified my logging tables to output the full, unclipped 2-byte MAF Hz value to EvoScan. I've seen up to 2300hz on my logger. Using that, some technical specs for the MAF and some other calculations that have absolutely nothing to do with percentages or 'load', I've been able to calculate the approximate CFM intake of the engine at any given RPM/airflow value. I've checked it against the compressor flow charts, and it's well within range of what my setup should flow at those intervals.
Yep, its just airflow which can be interpreted for load.

Whats your setup for reference, I wonder what would peg the stock MAS?

It has to be somewhere around the stock MAS records, as people make good gains by going to larger MAS.
 

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The calculation is done by you, not the ECU.
Every logger out there uses the same formula. I have yet to see someone post a customized load formula for their specific setup.

Not that it matters. You have to know how to interpret the reported memory variable as airflow before you can figure it out as a percentage of theoretical maximum airflow, no?

Whats your setup for reference, I wonder what would peg the stock MAS?
Who said my MAF is pegged? It's still got plenty of room to go.

Anyway, I'm running 14Bs at low boost and a fairly rough tune.
 

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This percentage based load thing is a leftover from before the Evo guys properly understood their code. I've been reading through the last 5 years of posts on 4 different boards. It is flat out WRONG, but since it's so entrenched and people are so used to it, it's stuck.
I bought my evo years after they came out, and was slow to the tuning/logging scene (a year after I bought the car), but I have always (the last 3ish years) seen and heard load represented as a regular number, and not a percentage. Stock maps on the VR4 and Evo have their load in standard measure; 160 as the "normal" VR4 limit (400 at peak), and Evos I believe were around 260 at peak (but didnt jump 160 to 400 in a single column like VR4s.

I agree, load is definitely not a percentage.

It's just like the thing we deal with for so-called "MR" gears and the mythical "JDM 13Gs". The MAF sensor doesn't stop reading at 1603hz either. Bad info got out there, and now it's impossible to change it.
What? No MR gears and no JDM 13Gs? Argh! What kind of unicorn VR4 did I buy? :mad:

If my evo sells and I can get the Evo3 car wrapped up, I'll be happy to let you know how far the stock MAF reads ... although you already know the answer, couldn't hurt for me to post a few logs to show other people. ;)

I forget the exact number but IIRC my scanmaster pegs at 16xx when looking at the MAS sensor on various pulls. With 9b's and with 13t's it didn't take anything to hit that number either (typically before 4k rpms).
I would guess towards that being an OBDI/formula limit? IIRC the stock evo rom MAF scaling stops at 1600Hz (since stock cars dont pass that), but highly modded cars can run much, much more. Scanmaster might see that as the highest value, or maybe the OBDI ECU caps the reading in the code somewhere, but I bet if you took that same MAF and put it on a 2G pushing enough air, it'll read past 16xxHz.

My friend's "well over 500" awhp evo was pushing somewhere around 2800Hz if I remember right, on the stock MAF, and he had the MAF scaling axis re-scaled accordingly.
 

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IIRC the stock evo rom MAF scaling stops at 1600Hz
The stock 1-byte logging value saturates at 1603 hz (6.29*255). It physically can't count any higher than 255. We know the scaling is correct for that because it's been verified against dealer scan tools.

Using Kibwe's logic you could just use an arbitrary formula and have it read to 3GHz (11764*255), but it'd still be wrong.

Internally the ECU uses a 2-byte value for map lookups and other things.

I suspect the reason the stock value pegs at 1603 is because Mitsu didn't care to do troubleshooting logging at WOT. The dealer scan tool diagnostics would only be concerned with emissions related diagnostics. They couldn't rescale it to read higher because then they'd lose resolution at the idle and cruise sampling rates where it's important.

Even the internal MAF calibration tables peak out around 1600 hz. Speculation being that at flow rates over 1600 hz, can just use a static resolution. You don't need a "high definition" MAF when you're flowing over 600 cfm of air and running open loop.
 

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I bought my evo years after they came out, and was slow to the tuning/logging scene (a year after I bought the car), but I have always (the last 3ish years) seen and heard load represented as a regular number, and not a percentage. Stock maps on the VR4 and Evo have their load in standard measure; 160 as the "normal" VR4 limit (400 at peak), and Evos I believe were around 260 at peak (but didnt jump 160 to 400 in a single column like VR4s.

I agree, load is definitely not a percentage.



What? No MR gears and no JDM 13Gs? Argh! What kind of unicorn VR4 did I buy? :mad:

If my evo sells and I can get the Evo3 car wrapped up, I'll be happy to let you know how far the stock MAF reads ... although you already know the answer, couldn't hurt for me to post a few logs to show other people. ;)



I would guess towards that being an OBDI/formula limit? IIRC the stock evo rom MAF scaling stops at 1600Hz (since stock cars dont pass that), but highly modded cars can run much, much more. Scanmaster might see that as the highest value, or maybe the OBDI ECU caps the reading in the code somewhere, but I bet if you took that same MAF and put it on a 2G pushing enough air, it'll read past 16xxHz.

My friend's "well over 500" awhp evo was pushing somewhere around 2800Hz if I remember right, on the stock MAF, and he had the MAF scaling axis re-scaled accordingly.
The 3000gtvr4/2gdsm maf drops counts after 50 lb/min. The evo maf is said to be good for 60ish lb/min.
 

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My friend's "well over 500" awhp evo was pushing somewhere around 2800Hz if I remember right, on the stock MAF, and he had the MAF scaling axis re-scaled accordingly.
I am running an evo maf in my TT and IIRC I saw 3xxx hz on my SAFC, I would need to check it out again to have a real number to bring.

Eric
 

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Every logger out there uses the same formula. I have yet to see someone post a customized load formula for their specific setup.

Not that it matters. You have to know how to interpret the reported memory variable as airflow before you can figure it out as a percentage of theoretical maximum airflow, no?

IDK, I wouldn't get into all that if I just had the max Hz signal for the stock guage or the maximum my setup at a given boost was capable of. That would be my reference point.



Who said my MAF is pegged? It's still got plenty of room to go.
IDK, wasn't me. I just wanted to know what you were getting as a reference point with PSI numbers.

Ex if your 14b setup which Trevor took to 55x AWHP gave a max reading of 2xxx Hz on the stock guage, its a reference point. Not very accurate but something to compare against. _____ AWHP = ______ Hz on the stock MAS type of reference.

Anyway, I'm running 14Bs at low boost and a fairly rough tune.
Cool, hopefully I can get my evo 3 setup going and I'll have some numbers to throw into the mix for reference. Then again scanmaster won't give anything higher than 16xx :( .
 

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Thanks Trevor for taking time to post this useful information. I do not currently own a TT but I am putting together a game plan for one and this type of information is valuable to me, whether or not I run an AEM system to tune. Sizing injectors properly and using an AFPR from the get go should make everyone's life easier, whether or not they use other means to control timing.

At a minimum, my comments should drag this thread to the top again. And I hope others find this kind of information as useful as I do.

Happy Holidays to you and yours!!!
 

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Discussion Starter #234
Thanks!

Wow...1st post is so old I can't edit it.

***2012 EDIT***
E85 as follows (0.78 BSFC, 9.68 lbs/hr to cc/min conversion)

550cc 350-437HP (326-447 w/adjustable)
580cc 369-461 (344-471)
650cc 414-516 (385-528)
680cc 433-540 (403-553)
720cc 459-572 (427-585)
750cc 478-596 (445-609)
780cc 497-620 (463-634)
850cc 541-675 (504-691)
950cc 605-755 (563-772)
1000cc 637-794 (593-813)
1050cc 669-834 (623-853)
1150cc 733-913 (682-934)
1250cc 796-993 (741-1016)
1450cc 924-1152 (860-1178)
1600cc 1019-1271 (949-1300)
1650cc 1051-1311 (978-1341)
2000cc 1274-1589 (1186-1625)

*** End 2012 EDIT ***
 

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Thanks!

Wow...1st post is so old I can't edit it.

***2012 EDIT***
E85 as follows (0.78 BSFC, 9.68 lbs/hr to cc/min conversion)

1150cc 733-913 (682-934)
1250cc 796-993 (741-1016)
1450cc 924-1152 (860-1178)


*** End 2012 EDIT ***
Just to be clear, are these awhp numbers or at the crank? It seems you would calculate everything at crank and so I assume the later.

I also see I have several to chose from in this range to select for E85 if I use an AFPR. My target is 750HP at the wheels and a guesstimate of 20% max drive line loss.

Also curious how you feel about turbos of different sizes to minimize lag. Be gentle, I am still learning but could you give me a "for example"?

Edit: I am really more concerned with off the line performance to 60mph than top speed.
 

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Discussion Starter #237 (Edited)
Numbers are in crank power.

With the stock ECU it's always better to pick injectors that will support your goals without a whole lot of overhead. It just makes tuning way easier. I'd probably run with the 950's if I was going for 750 crank HP.

Just my opinion here on drivetrain loss. I believe it increases with power but at a much lower rate than most believe. I'm more of the mind that it's 80-110 HP off the top (maybe a little more if you're running some crazy heavy wheels/tires).

As far as runnig two different turbos I'm not a fan. Even with identical turbine housings & wheels the exhaust manifod pressure between both banks will not be equal and therefore the VE's of both banks will not match up. The difference in back pressure will be caused by the varying turbine wheel speed (as a turbine wheel spins faster it poses more and more of a restriction to flow). Much better off just properly sizing your turbo(s) for your goal from the get go..there are plenty of choices.
 

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Numbers are in crank power.

I'd probably run with the 950's if I was going for 750 crank HP.
My target is 750HP at the wheels
Thanks for taking time to clarify and answer my questions.

I am still researching twin vs. single turbo pros and cons. If I do a total custom exhaust and intake system, I am kinda leaning toward a single billet turbo but I a concerned about too much lag. Here again, I really am more concerned with 0-60mph times.

Cheers!
 

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Discussion Starter #239
Reading comp FTL...lol. In that case 1050's...maybe 1150's. You're on the edge there. Hell I'd proably get ID1000's and a decent supply system so you could run 55-60 psi base.

As far as singles go they're not necessarily slower to 60 mph. I don't think anyones gone larger than me (GTX4202R with a 1.44 AR hot side) and my car is stupid quick to 60 mph. Granted it's on a 3.7L but the point is you just have to pick the right turbo(s) for the job and motor they're attached to. Screw that up, single or twins, and you'll have a lag monster.
 

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Reading comp FTL...lol. In that case 1050's...maybe 1150's. You're on the edge there. Hell I'd proably get ID1000's and a decent supply system so you could run 55-60 psi base.
I was looking at the Injector Dynamics and the DeatschWerks DSM injectors. I hear good things about both of these mfg's.

1995-99 | DeatschWerks

Thanks again!
 
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