VE Table Cracked
08-03-2004, 10:17 AM
#161
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A little since you need kpa instead of PSI or inHg or whatever. you will need to convert to kpa. Using chrisb's LFA you can calculate a new ve table. Or you can use HPTuners LTFT histogram to help get you trims squared away since that table is referenced by map and rpm and so is the ve table. Oh and IAT to kelvin is IAT+273
There is also an editor conversion tool in HPTuners. You can usr that to convert map from imperial to kpa
There is also an editor conversion tool in HPTuners. You can usr that to convert map from imperial to kpa
Last edited by HumpinSS; 08-03-2004 at 10:27 AM.
08-03-2004, 11:34 AM
#162
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Yeah I am actually playing with Chris B's calculator now, and it's not helping out much. It seems that the two programs log different parameters....I'm looking at some of the optional scanning PIDs in HP tuners...what is the difference between:
mass airflow and mass airflow 2? I think the biggest problem I'm having with the analyzer is that HP tuners is measuring MAF in lb/min, and the analyzer is looking for gm/sec. any way to convert this?
mass airflow and mass airflow 2? I think the biggest problem I'm having with the analyzer is that HP tuners is measuring MAF in lb/min, and the analyzer is looking for gm/sec. any way to convert this?
08-14-2004, 10:57 PM
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In HPT, you can change the units of measure in the scan tool window. Prefereces > Display Units. Set it to Metric, and resave the data as a new .csv...
I've been playing with the formulas, and I'm getting some legit numbers. I could spend 40 years doing this by hand though... does anyone have a simple Excel spreadsheet handy? I have the intellect of a 5 year old when it comes to Excel.
I'm really intrugued here because my cam runs best on my stock VE table. The numbers I'm getting back are "legit", but they're about 15-20 points off from what I'm running in the low rpm colums and I know others out there have done lots of mods this section of theirs after a cam install.
Does the IFR table have anything to do with this equasion or any VE changes in general? Does it matter if the IFR table is "straight across" or if it's a scaled?
I've been playing with the formulas, and I'm getting some legit numbers. I could spend 40 years doing this by hand though... does anyone have a simple Excel spreadsheet handy? I have the intellect of a 5 year old when it comes to Excel.
I'm really intrugued here because my cam runs best on my stock VE table. The numbers I'm getting back are "legit", but they're about 15-20 points off from what I'm running in the low rpm colums and I know others out there have done lots of mods this section of theirs after a cam install.
Does the IFR table have anything to do with this equasion or any VE changes in general? Does it matter if the IFR table is "straight across" or if it's a scaled?
08-14-2004, 11:09 PM
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Originally Posted by marc_w
In HPT, you can change the units of measure in the scan tool window. Prefereces > Display Units. Set it to Metric, and resave the data as a new .csv...
I've been playing with the formulas, and I'm getting some legit numbers. I could spend 40 years doing this by hand though... does anyone have a simple Excel spreadsheet handy? I have the intellect of a 5 year old when it comes to Excel.
I'm really intrugued here because my cam runs best on my stock VE table. The numbers I'm getting back are "legit", but they're about 15-20 points off from what I'm running in the low rpm colums and I know others out there have done lots of mods this section of theirs after a cam install.
Does the IFR table have anything to do with this equasion or any VE changes in general? Does it matter if the IFR table is "straight across" or if it's a scaled?
I've been playing with the formulas, and I'm getting some legit numbers. I could spend 40 years doing this by hand though... does anyone have a simple Excel spreadsheet handy? I have the intellect of a 5 year old when it comes to Excel.
I'm really intrugued here because my cam runs best on my stock VE table. The numbers I'm getting back are "legit", but they're about 15-20 points off from what I'm running in the low rpm colums and I know others out there have done lots of mods this section of theirs after a cam install.
Does the IFR table have anything to do with this equasion or any VE changes in general? Does it matter if the IFR table is "straight across" or if it's a scaled?
08-14-2004, 11:55 PM
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Cool. I heard a few people talking about their IFR tables being like, 3.08 across the board. I was wondering if their VE tables were different (from the factory) because of that.
EDIT:
Linear or Non-Linear IFR tables. That's the wording I was looking for.
I'm non-linear, and my VE table is a good amount higher down low than what I've seen others post. (Their IFR's are unknown)
EDIT:
Linear or Non-Linear IFR tables. That's the wording I was looking for.
I'm non-linear, and my VE table is a good amount higher down low than what I've seen others post. (Their IFR's are unknown)
Last edited by marc_w; 08-15-2004 at 12:21 AM.
08-15-2004, 12:53 AM
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Originally Posted by marc_w
In HPT, you can change the units of measure in the scan tool window. Prefereces > Display Units. Set it to Metric, and resave the data as a new .csv...
I've been playing with the formulas, and I'm getting some legit numbers. I could spend 40 years doing this by hand though... does anyone have a simple Excel spreadsheet handy? I have the intellect of a 5 year old when it comes to Excel.
I'm really intrugued here because my cam runs best on my stock VE table. The numbers I'm getting back are "legit", but they're about 15-20 points off from what I'm running in the low rpm colums and I know others out there have done lots of mods this section of theirs after a cam install.
Does the IFR table have anything to do with this equasion or any VE changes in general? Does it matter if the IFR table is "straight across" or if it's a scaled?
I've been playing with the formulas, and I'm getting some legit numbers. I could spend 40 years doing this by hand though... does anyone have a simple Excel spreadsheet handy? I have the intellect of a 5 year old when it comes to Excel.
I'm really intrugued here because my cam runs best on my stock VE table. The numbers I'm getting back are "legit", but they're about 15-20 points off from what I'm running in the low rpm colums and I know others out there have done lots of mods this section of theirs after a cam install.
Does the IFR table have anything to do with this equasion or any VE changes in general? Does it matter if the IFR table is "straight across" or if it's a scaled?
08-15-2004, 09:49 AM
#168
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Originally Posted by HumpinSS
The IFR table doenst affect the ve formula (rememebr the ve formula is an airmass formula that is used to figure out fueling), changes to the ve table would be more accurate if the IRF table is stock
I just want to elaborate and be certain that everyone understands what I meant with Linear vs Non-Linear IFR tables...
Say I happen to get a linear IFR table from the factory. 3.15 straight across the table. Lets use that VE table as the "control" for my example...
Now my IFR table is non linear from the factory... The values are 2.80 @ 0 vac scaled up to 3.15 at 80 vac.
Say I'm down in the low vacuum range of the VE and IFR table. Shouldn't these VE numbers differ from the linear VE table, for the fact that the injectors aren't flowing the same amount of fuel?
08-15-2004, 10:11 AM
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Originally Posted by marc_w
Okay, I'm pretty certain I understand.
I just want to elaborate and be certain that everyone understands what I meant with Linear vs Non-Linear IFR tables...
Say I happen to get a linear IFR table from the factory. 3.15 straight across the table. Lets use that VE table as the "control" for my example...
Now my IFR table is non linear from the factory... The values are 2.80 @ 0 vac scaled up to 3.15 at 80 vac.
Say I'm down in the low vacuum range of the VE and IFR table. Shouldn't these VE numbers differ from the linear VE table, for the fact that the injectors aren't flowing the same amount of fuel?
I just want to elaborate and be certain that everyone understands what I meant with Linear vs Non-Linear IFR tables...
Say I happen to get a linear IFR table from the factory. 3.15 straight across the table. Lets use that VE table as the "control" for my example...
Now my IFR table is non linear from the factory... The values are 2.80 @ 0 vac scaled up to 3.15 at 80 vac.
Say I'm down in the low vacuum range of the VE and IFR table. Shouldn't these VE numbers differ from the linear VE table, for the fact that the injectors aren't flowing the same amount of fuel?
08-15-2004, 10:43 AM
#170
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PCM first works out airflow, then fuel.
It calculates it has X grams of air in the cylinder (MAF/VE table), it knows it has a target AFR of Y, therefore it needs to inject Z grams of fuel. Z = X / Y
Once it has worked out it needs Z grams of fuel, it then looks to the IFR table to work out how long to pulse the injector for to get Z grams of fuel.
It calculates it has X grams of air in the cylinder (MAF/VE table), it knows it has a target AFR of Y, therefore it needs to inject Z grams of fuel. Z = X / Y
Once it has worked out it needs Z grams of fuel, it then looks to the IFR table to work out how long to pulse the injector for to get Z grams of fuel.
08-15-2004, 10:55 AM
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Originally Posted by gameover
PCM first works out airflow, then fuel.
It calculates it has X grams of air in the cylinder (MAF/VE table), it knows it has a target AFR of Y, therefore it needs to inject Z grams of fuel. Z = X / Y
Once it has worked out it needs Z grams of fuel, it then looks to the IFR table to work out how long to pulse the injector for to get Z grams of fuel.
It calculates it has X grams of air in the cylinder (MAF/VE table), it knows it has a target AFR of Y, therefore it needs to inject Z grams of fuel. Z = X / Y
Once it has worked out it needs Z grams of fuel, it then looks to the IFR table to work out how long to pulse the injector for to get Z grams of fuel.
08-15-2004, 11:01 AM
#172
Originally Posted by gameover
PCM first works out airflow, then fuel.
It calculates it has X grams of air in the cylinder (MAF/VE table), it knows it has a target AFR of Y, therefore it needs to inject Z grams of fuel. Z = X / Y
Once it has worked out it needs Z grams of fuel, it then looks to the IFR table to work out how long to pulse the injector for to get Z grams of fuel.
It calculates it has X grams of air in the cylinder (MAF/VE table), it knows it has a target AFR of Y, therefore it needs to inject Z grams of fuel. Z = X / Y
Once it has worked out it needs Z grams of fuel, it then looks to the IFR table to work out how long to pulse the injector for to get Z grams of fuel.
Anyone got a little spreadsheet or prog for this formula yet?
08-15-2004, 03:39 PM
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Originally Posted by Another_User
So basically, lying to the PCM about the IFR could be bad? (And may also explain why when I compensated for a lean condition with the IFR, now HPTuners reports all my air/fuel ratios wrong?)
I need to go drive into Boston in 20 minutes. I'm nervous about my truck acting up.
08-16-2004, 09:42 AM
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I made low RPM VE changes yesterday, reset fuel trims, and did an idle relearn. The truck ran great yesterday.
FWIW, I'm going to write a Unix (bourne shell) script that will sort through a CSV and calculate VE's. I'm not sure if it'll be handy to anyone.
I spent a good amount of time trying to get the LS1Analyzer working with my HPT logs, and I'm just spinning my wheels on it. I'm not familiar with any logging tools other than HPT, and I'm not sure what LS1A is exactly looking for.
FWIW, I'm going to write a Unix (bourne shell) script that will sort through a CSV and calculate VE's. I'm not sure if it'll be handy to anyone.
I spent a good amount of time trying to get the LS1Analyzer working with my HPT logs, and I'm just spinning my wheels on it. I'm not familiar with any logging tools other than HPT, and I'm not sure what LS1A is exactly looking for.
08-16-2004, 10:02 AM
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Originally Posted by marc_w
I made low RPM VE changes yesterday, reset fuel trims, and did an idle relearn. The truck ran great yesterday.
FWIW, I'm going to write a Unix (bourne shell) script that will sort through a CSV and calculate VE's. I'm not sure if it'll be handy to anyone.
I spent a good amount of time trying to get the LS1Analyzer working with my HPT logs, and I'm just spinning my wheels on it. I'm not familiar with any logging tools other than HPT, and I'm not sure what LS1A is exactly looking for.
FWIW, I'm going to write a Unix (bourne shell) script that will sort through a CSV and calculate VE's. I'm not sure if it'll be handy to anyone.
I spent a good amount of time trying to get the LS1Analyzer working with my HPT logs, and I'm just spinning my wheels on it. I'm not familiar with any logging tools other than HPT, and I'm not sure what LS1A is exactly looking for.
You have to re-define what LFA looks for in the logs. Either that or change them to the EFILive default
MAP,RPM,CYLAIR,IAT,ECT Ect. If you need help gettting it to work maybe you can send me a message and I'll be able to help.
The Unix script that you are writing, will it be able to group map and rpm, then average out the ve's so that it coresponds to the ve table the editor
08-16-2004, 12:12 PM
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Originally Posted by HumpinSS
You have to re-define what LFA looks for in the logs. Either that or change them to the EFILive default
MAP,RPM,CYLAIR,IAT,ECT Ect. If you need help gettting it to work maybe you can send me a message and I'll be able to help.
MAP,RPM,CYLAIR,IAT,ECT Ect. If you need help gettting it to work maybe you can send me a message and I'll be able to help.
The Unix script that you are writing, will it be able to group map and rpm, then average out the ve's so that it coresponds to the ve table the editor
08-16-2004, 12:17 PM
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Originally Posted by marc_w
Yeah, I've converted over my CSV headers, and then I tried adding regular HPT aliases to the known column types, but without any luck. I'll crank on it a little more tonight. I appreciate the offer!
Do you mean basically 'build' a VE table like LS1A does? No, unfortunately it's going to be very very simple. Nothing more than a Unix version of an Excel spreadsheet that's setup to do just calculations of different columns.
Do you mean basically 'build' a VE table like LS1A does? No, unfortunately it's going to be very very simple. Nothing more than a Unix version of an Excel spreadsheet that's setup to do just calculations of different columns.
oh I know it isnt going to be that easy
that is why i asked maybe youfound a nix way of doing it. I tried in Java, needless to say it isnt finished
08-17-2004, 09:53 PM
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Originally Posted by NoGo
I have been working on the VE table quite a bit lately and I think I found the solution.
Thanks to gameover for some key hints.
The VE table looks as though it is in meters cubed, it is just not used like a conventional VE table. The VE values are such that the PCM can directly backcalculate to g/cyl, the primary means to determine fueling and timing.
This is what makes it so confusing. You can't solve for air mass, you have to solve for g/cyl.
Anyhoo, here is the equation
VE = ((massflow * IAT / (MAP * RPM * Displacement))
Massflow: grams/sec
IAT: Degrees Kelvin
MAP: Bar
RPM: Duh!
Displacement: Cubic Meters
To solve for the massflow in g/sec simply re-arrange the equation.
Massflow = (VE * MAP * RPM * Displacement) / IAT
My old method of "Divide by 30" works okay because we are inadvertantly solving for a volume ratio. The molar mass of air is 28.96 g/mol.
I have compared the above equation to every bit of data that I have ever collected for a stock car, and the data matches up perfectly.
Any corrections, comments, or blinding errors please let me know.
Thanks,
Kevin
Thanks to gameover for some key hints.
The VE table looks as though it is in meters cubed, it is just not used like a conventional VE table. The VE values are such that the PCM can directly backcalculate to g/cyl, the primary means to determine fueling and timing.
This is what makes it so confusing. You can't solve for air mass, you have to solve for g/cyl.
Anyhoo, here is the equation
VE = ((massflow * IAT / (MAP * RPM * Displacement))
Massflow: grams/sec
IAT: Degrees Kelvin
MAP: Bar
RPM: Duh!
Displacement: Cubic Meters
To solve for the massflow in g/sec simply re-arrange the equation.
Massflow = (VE * MAP * RPM * Displacement) / IAT
My old method of "Divide by 30" works okay because we are inadvertantly solving for a volume ratio. The molar mass of air is 28.96 g/mol.
I have compared the above equation to every bit of data that I have ever collected for a stock car, and the data matches up perfectly.
Any corrections, comments, or blinding errors please let me know.
Thanks,
Kevin
How did you come up with this? This is amazing!!!!
08-18-2004, 10:12 AM
#179
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Originally Posted by P Mack
Here's what I got using dimensional analysis (canceling units):
VE = 3444 * MAF * (273 + IAT)/(MAP * RPM *Displacement)
units:
VE = %
MAF = grams/second
T = Celsius
MAP = kPa
Displacement = liters
Seems to be pretty accurate with the data i've got but i think it'll be better when i switch my granitelli maf back to stock. I got excel to calculate VE for all the points in my log file, now i gotta figure out how to sort it into something useful.
VE = 3444 * MAF * (273 + IAT)/(MAP * RPM *Displacement)
units:
VE = %
MAF = grams/second
T = Celsius
MAP = kPa
Displacement = liters
Seems to be pretty accurate with the data i've got but i think it'll be better when i switch my granitelli maf back to stock. I got excel to calculate VE for all the points in my log file, now i gotta figure out how to sort it into something useful.
I've got a question on the 3444 number. Where did that come from?
Is this formula 5.7L specific?
08-18-2004, 11:57 AM
#180
No, it's not 5.7 liter specific. You can plug in any displacement you want. The 3444 is a combination of one intake stroke for every 2 revolutions (per cylinder), the gas constant for air (.287 kJ/kg K), 60 seconds per minute, and times 100 to make it a percent. The conversion from liters to cubic meters and from kilograms to grams cancel each other out. I can post the derivation if you really want.