Anyone Datalogging AFR and Injector Duty? I want to calculate CFM of Rotary.
#1
Senior Member
Thread Starter
Anyone Datalogging AFR and Injector Duty? I want to calculate CFM of Rotary.
Hey I am working on an engine CFM calculator that will tell the exact CFM of your engine based on injector duties and AFR. This will be useful when selecting a new turbo.
I am curious what our engines flow. So I am asking for a datalog because I dont have access to my car right now.
This will work best if you datalog a long pull in 3rd or 4th from 2k-redline. (Of course on a closed course, or dyno
If you have a datalog with this displayed:
Inj Duty
RPM
Boost
AFR (or a voltage from a wb and the chart used to convert it)
email it to: rotor_rage@yahoo.com
You must also tell me what injector sizes you are running, where your staging bar is and your static fuel pressure.
Please include a mods list: porting, exh turbo size A/R etc...
I will post the excel spreadsheet when I am done.
Justin
I am curious what our engines flow. So I am asking for a datalog because I dont have access to my car right now.
This will work best if you datalog a long pull in 3rd or 4th from 2k-redline. (Of course on a closed course, or dyno
If you have a datalog with this displayed:
Inj Duty
RPM
Boost
AFR (or a voltage from a wb and the chart used to convert it)
email it to: rotor_rage@yahoo.com
You must also tell me what injector sizes you are running, where your staging bar is and your static fuel pressure.
Please include a mods list: porting, exh turbo size A/R etc...
I will post the excel spreadsheet when I am done.
Justin
#2
Originally Posted by pistonsuk
Hey I am working on an engine CFM calculator that will tell the exact CFM of your engine based on injector duties and AFR. This will be useful when selecting a new turbo.
I am curious what our engines flow. So I am asking for a datalog because I dont have access to my car right now.
This will work best if you datalog a long pull in 3rd or 4th from 2k-redline. (Of course on a closed course, or dyno
If you have a datalog with this displayed:
Inj Duty
RPM
Boost
AFR (or a voltage from a wb and the chart used to convert it)
email it to: rotor_rage@yahoo.com
You must also tell me what injector sizes you are running, where your staging bar is and your static fuel pressure.
Please include a mods list: porting, exh turbo size A/R etc...
I will post the excel spreadsheet when I am done.
Justin
I am curious what our engines flow. So I am asking for a datalog because I dont have access to my car right now.
This will work best if you datalog a long pull in 3rd or 4th from 2k-redline. (Of course on a closed course, or dyno
If you have a datalog with this displayed:
Inj Duty
RPM
Boost
AFR (or a voltage from a wb and the chart used to convert it)
email it to: rotor_rage@yahoo.com
You must also tell me what injector sizes you are running, where your staging bar is and your static fuel pressure.
Please include a mods list: porting, exh turbo size A/R etc...
I will post the excel spreadsheet when I am done.
Justin
#3
The shy megalomaniac
iTrader: (2)
I don't think logging boost is a reliable way of measuring air flow. For example, you can have 20psi boost but nearly zero CFM if the air does not have any velocity. In such an example, there is nearly as much pressure coming back from the port intake as the compressor side.
MAF sensors do this not boost.
MAF sensors do this not boost.
#5
Senior Member
Thread Starter
Originally Posted by NeoTuri
I don't think logging boost is a reliable way of measuring air flow. For example, you can have 20psi boost but nearly zero CFM if the air does not have any velocity. In such an example, there is nearly as much pressure coming back from the port intake as the compressor side.
MAF sensors do this not boost.
MAF sensors do this not boost.
Example: 13BT, 15psi, 60-1 turbo, streetport = 400lbs/min @ 4000 and 650lbs/min @ 7000
^ these are not real. Just an example.
all i need to calculate lbs/min of air is AFR and lbs/min of fuel.
Justin
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#8
Senior Member
Thread Starter
Originally Posted by NeoTuri
Thanks,
To get back on topic, I will be datalogging AFR, load/boost, injector duty, etc as soon as I get the FD back together in the next week or two.
To get back on topic, I will be datalogging AFR, load/boost, injector duty, etc as soon as I get the FD back together in the next week or two.
Justin
#10
Originally Posted by pistonsuk
This is my reasoning:
Airflow=Fuelflow * AFR
=(InjDuty)*(# of Inj)*(size of Inj)*AFR
make sense?
Justin
Airflow=Fuelflow * AFR
=(InjDuty)*(# of Inj)*(size of Inj)*AFR
make sense?
Justin
Also how you gonna know teh weight of air and fuel?
#11
Senior Member
Thread Starter
Originally Posted by cardzrule
In hondas you gotta know teh fuel pressure too. are mazdas different?
Originally Posted by cardzrule
Also how you gonna know teh weight of air and fuel?
Justin
#12
Originally Posted by pistonsuk
Injectors are volume-flowrated (cc/min), this can be converted to mass-flowrate (lbs/min) by simply multipling by the density of fuel. There are calculators online for this. At this point you then have a mass-flowrate (lbs/min) of fuel which can be multiplied by the AFR (air to fuel mass ratio) to find the mass-flowrate of the air.
Also AFR aint all that accurate is it? I mean even teh widebands dont read rite when they get hot or when air is flowing into teh exhaust from air pump or exhaust leaks.
Last edited by cardzrule; 02-20-06 at 01:07 PM.
#13
Senior Member
Thread Starter
Originally Posted by cardzrule
So you saying that fuel weighs teh same no matter what temp?
Originally Posted by cardzrule
How com fuel dont get hotter when pressurized like air does from a turbo?
Originally Posted by cardzrule
Also dont teh fuel get hot going into teh hot engine bay?
Originally Posted by cardzrule
Also you saying that 20 psi of air weighs teh same as 0 psi air and that 50 deg air weighs teh same as 200 deg air?
Originally Posted by cardzrule
Also AFR aint all that accurate is it? .
Justin
#14
Originally Posted by pistonsuk
Nope. The pressure and temperature is taken into account when calculating the mass of the volume of air.
Originally Posted by pistonsuk
From FJO's website: Accuracy better than 0.1 AFR over the range 10.5:1 to 15.5:1
Also i got a question. If teh wideband sensor only works 750-850 C temp
http://www.pectel.org.uk/assets/NTKWideBand.pdf
wich is same as 1382-1562 F
http://www.onlineconversion.com/temperature.htm
and teh rotery engine exhaust is 1650-1700 F
http://www.rhinoracing.com/yaw/carb_tuning.htm
then how can teh sensor be accurate if its past its temp range? Teh way i figger if teh company sez teh senor works good 1382-1562 F then that mean it dont work good more or less than that. So if teh rx7 is more temp than that then there aint no way teh sensor gonna be 0.1 AFR accurate on a rx7 like fjo sez. Make sense?
#15
Maybbe i can understand better if you show one ez math problem?
Inj Duty 80
RPM 5000
Boost 10
AFR 11
You must also tell me what injector sizes you are running
550
where your staging bar
NONE
your static fuel pressure.
43.5
Please include a mods list: porting, exh turbo size A/R etc...
street port - stock s4 tII turbo
OK so what is teh cfm for that?
Inj Duty 80
RPM 5000
Boost 10
AFR 11
You must also tell me what injector sizes you are running
550
where your staging bar
NONE
your static fuel pressure.
43.5
Please include a mods list: porting, exh turbo size A/R etc...
street port - stock s4 tII turbo
OK so what is teh cfm for that?
#16
Senior Member
Thread Starter
Originally Posted by cardzrule
Ge i still dont understand how you gonna figger out teh cfm if you dont know teh weight of teh air. Guess i need more schooling.
Density is a ratio of mass (kg) over volume (m^3). Fore example styrafoam has a low density (not alot of mass per unit volume) on the other hand, steel has a much higher density.
Volume is not a ratio of anything. Following the above example: we both know it is possible to have say 1kg of styrafoam or steel. Now the density of these materials would tell us how much space that mass would fill.
Density of almost anything (that I know of) changes with temperature and pressure. Gases are the best representations of this. As I mentioned before when analyzing solids and liquids we assume density is not a function of temperature and pressure.
Therefore if given a pressure, temperature and composition (material, i.e. air) the density of that material is known. Then using the above definition of density if the volume of the material is known the mass can be calulated.
Originally Posted by cardzrule
o you didnt say teh datalog had to have a fjo wideband. Most peeps have teh stock narrowband 02 sensor.
Originally Posted by cardzrule
Also i think that fjo accuracy is in a lab and not on a real car.
Originally Posted by cardzrule
Those engineer doods dont know real world stuff too well.
Originally Posted by cardzrule
If teh wideband sensor only works 750-850 C temp
http://www.pectel.org.uk/assets/NTKWideBand.pdf
wich is same as 1382-1562 F
http://www.pectel.org.uk/assets/NTKWideBand.pdf
wich is same as 1382-1562 F
Now, I dont know exactly why they post 750-850C as operating temps. But I do know from experience that it is very common for manufacturers to claim a limited range to their senor simply because it is only over that limited range that the sensor is linear within the specified limits given. For example FJO claims their unit is good to 0.1AFR, this is of course over the specified operating range (750-850C), however the unit may be good to 0.2AFR from say 500-1100C.
Originally Posted by cardzrule
http://www.onlineconversion.com/temperature.htm
and teh rotery engine exhaust is 1650-1700 F
and teh rotery engine exhaust is 1650-1700 F
Originally Posted by cardzrule
http://www.rhinoracing.com/yaw/carb_tuning.htm
then how can teh sensor be accurate if its past its temp range? Teh way i figger if teh company sez teh senor works good 1382-1562 F then that mean it dont work good more or less than that. So if teh rx7 is more temp than that then there aint no way teh sensor gonna be 0.1 AFR accurate on a rx7 like fjo sez. Make sense?
then how can teh sensor be accurate if its past its temp range? Teh way i figger if teh company sez teh senor works good 1382-1562 F then that mean it dont work good more or less than that. So if teh rx7 is more temp than that then there aint no way teh sensor gonna be 0.1 AFR accurate on a rx7 like fjo sez. Make sense?
Justin
#17
Senior Member
Thread Starter
Originally Posted by cardzrule
Maybbe i can understand better if you show one ez math problem?
Inj Duty 80
RPM 5000
Boost 10
AFR 11
You must also tell me what injector sizes you are running
550
where your staging bar
NONE
your static fuel pressure.
43.5
Please include a mods list: porting, exh turbo size A/R etc...
street port - stock s4 tII turbo
OK so what is teh cfm for that?
Inj Duty 80
RPM 5000
Boost 10
AFR 11
You must also tell me what injector sizes you are running
550
where your staging bar
NONE
your static fuel pressure.
43.5
Please include a mods list: porting, exh turbo size A/R etc...
street port - stock s4 tII turbo
OK so what is teh cfm for that?
Send me your email.
Justin
#18
DETH TRP
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Originally Posted by cardzrule
Ge i still dont understand how you gonna figger out teh cfm if you dont know teh weight of teh air. Guess i need more schooling.
#19
Originally Posted by pistonsuk
Send me your email.
Justin
Justin
Mr Stevens my science teacher sez you cant calculate cfm with teh info ur asking for neway. Maybbe you should have a disclaimer or something on ur spreadsheet coz peeps gonna be pissed if they spend like 2000$ on a turbo that aint sized rite coz ur math was wrong.
Originally Posted by 4CN Air
Yes you do, with the most important class being English! j/k
#21
Senior Member
Thread Starter
Originally Posted by cardzrule
TY but I aint sending ne1 my email address coz I got too much spam already.
Originally Posted by cardzrule
Mr Stevens my science teacher sez you cant calculate cfm with teh info ur asking for neway. Maybbe you should have a disclaimer or something on ur spreadsheet coz peeps gonna be pissed if they spend like 2000$ on a turbo that aint sized rite coz ur math was wrong.
If either of you are interested pm me an email.
Justin
#22
pistonsuk....glad to see some engineers are putting time into the rotary....
i volenteer to check his math if needed....
hmm....fuel doesnt change density all that much because the fuel's saturation temperature....unless it is in the liquid-vapor state we can assume the density to be constant...to calculate the mass of air u can just consider air as a ideal gas and apply the ideal gas equation....PV=mRT....i would suggest that the data also include intake temp...(not sure if this was suggested)
the WB02 needs to be placed further downstream of the exhaust...they also suggest this on the website so that the engine heat does not ruin the sensor.....18-24inches away from the turbo if i remember correctly.....this lets the exhaust cool down a bit to be measured
i volenteer to check his math if needed....
hmm....fuel doesnt change density all that much because the fuel's saturation temperature....unless it is in the liquid-vapor state we can assume the density to be constant...to calculate the mass of air u can just consider air as a ideal gas and apply the ideal gas equation....PV=mRT....i would suggest that the data also include intake temp...(not sure if this was suggested)
the WB02 needs to be placed further downstream of the exhaust...they also suggest this on the website so that the engine heat does not ruin the sensor.....18-24inches away from the turbo if i remember correctly.....this lets the exhaust cool down a bit to be measured
#23
btw...by my spelling and grammer u can tell im destined to be an engineer...but damn.....trying to read some of these posts is nearly impossible........its like learning something from a teacher from calcutta
#25
Senior Member
Thread Starter
Originally Posted by NeoTuri
I'm street tuning today... will post my findings soon
Justin