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sn00k
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« on: June 21, 2012, 01:10:49 PM »
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what is the flow limitation of an RS4 MAF?
ive heard figures around 700hp? can this be increased by underscaling?
are there other good MAFs to use for this kind of power? aftermarket ones with calibration data to intepolate for the MLHFM?
any ideas are welcome.
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masterj
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« Reply #1 on: June 21, 2012, 02:45:30 PM »
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what is the flow limitation of an RS4 MAF?
ive heard figures around 700hp? can this be increased by underscaling?
are there other good MAFs to use for this kind of power? aftermarket ones with calibration data to intepolate for the MLHFM?
any ideas are welcome.
I'm thinking only aftermarket and then calibration.... But for that youd have to basically test and log what voltage output maf sensor gives at what airflow... |
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prj
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« Reply #2 on: June 22, 2012, 02:27:46 AM »
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Pro-M.
RS4 MAF maxes between 500 and 600 hp on pump.
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sn00k
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« Reply #3 on: June 22, 2012, 02:37:09 AM »
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"testing" 900whp+ worth of air into a 4-cylinder engine running on alcohol = explosion and total failure, this data needs to be 110% accurate from the start, and so that is not an option.
i dont know of any flowbench available to handle this kind of airflow.. not in the near vicinity.. so a calibration with the sensor out of the car will be most troublesome.
ah, Pro-M looks like the way to go.. them have 9 or even 30 point calibration data sheets available.. thanks prj!
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RS4boost
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« Reply #4 on: June 22, 2012, 09:39:22 AM »
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The output voltage of my RS4 MAF on dyno is exactly 4.95V at 7.400rpm with 1.75Bar holdboost and 639PS. 4,99V = 1996 Kg/h airflow is the absolute limit of the RS4 MAF. The inner diameter of a original RS4 MAF is 81mm (5153mm²) If you increase the inner diameter to 90mm (6362mm²) the MAF can measure until a airflow of 2464 Kg/h.    |
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« Last Edit: June 22, 2012, 09:50:12 AM by RS4boost »
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professor
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« Reply #5 on: June 22, 2012, 10:43:55 AM »
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Good info  |
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Seat Ibiza MK4 Cupra 1.8t 20V, stg3.
"Those 1.8T 20V machines are really tough" ©
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kenmac
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« Reply #6 on: June 22, 2012, 02:32:06 PM »
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RS4boost, using your example, you increased the diameter of the MAF by 23.4% and therefore increased the metered flow of the 4.9902v value by 23.4%. I assume you scale all the remaining values by the same constant? I've never had to scale a MAF before, so I was just confirming that this is how it's done.
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sn00k
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« Reply #7 on: June 22, 2012, 05:14:18 PM »
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this is nowhere near enough flow nor accuracy for this tune.. which will be 900whp+.. but thanks for the info! =)
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RS4boost
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« Reply #8 on: June 22, 2012, 10:58:15 PM »
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RS4boost, using your example, you increased the diameter of the MAF by 23.4% and therefore increased the metered flow of the 4.9902v value by 23.4%.
I assume you scale all the remaining values by the same constant?
That`s right. |
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« Last Edit: June 22, 2012, 11:35:59 PM by RS4boost »
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RS4boost
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« Reply #9 on: June 22, 2012, 11:13:32 PM »
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this is nowhere near enough flow nor accuracy for this tune.. which will be 900whp+.. but thanks for the info! =)
To use a 90mm MAF was only an example to show you how to calculate the max airflow and the right values for MLHFM. Of course you can also build a sensor with its own mass. The only thing to keep in mind is that you need to mount a grid in front of the MAF sensor to stabilize the airflow. If you don`t do this, the air pulsates with high turbulences and the sensor will give you bad values.  |
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« Last Edit: June 22, 2012, 11:28:38 PM by RS4boost »
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lulu2003
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« Reply #10 on: June 23, 2012, 06:02:03 AM »
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me7 takes the LMM table minus 200kg/h for real air mass. so it maxes out at 1800kg/h which is good for up to 650 HP
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prj
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« Reply #11 on: June 23, 2012, 03:05:16 PM »
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I don't like how you guys throw HP numbers around.
They are meaningless, because fuel is different...
I've maxed out RS4 MAF's at 570hp on pump fuel, and I've done over 650 on E85 and race fuel without it maxing.
Saying a maf is good for "xx hp" is completely wrong, because fuel octane rating makes a huge difference.
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lulu2003
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« Reply #12 on: June 24, 2012, 06:42:18 AM »
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I disagree again with you.
air mass is a very good indicator for estimating max power and at least to find out the right HFM for your tune.
even with different fuels.
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sn00k
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« Reply #13 on: June 24, 2012, 11:00:08 AM »
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well, the question was formulated as in topic, what to use for a given power.. ofc these engines are made to run on pump gas, so no e85 fueling needs to be discoussed here.
(sure, you can raise the VE even more with race fuel, vp, e85, methanol etc etc..)
and im pretty confident the RS4 MAF will be too small for this.. and will not need to be able to calculate this flow accurately.. unless MANY hours is spent calibrating one and fabricating new tracts, air straighteners etc.
this engine will be running on pump gas, 98.4 oct, with a boost of ~43.5psi, and the VE will be very high.. so ive decided to find me one of those Pro-M 92:s.. with a 30 point transfersheet made and calibrated in flowbench.. which should be perfect for this build.
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« Last Edit: June 24, 2012, 12:56:33 PM by sn00k »
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prj
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« Reply #14 on: June 24, 2012, 11:10:58 AM »
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I disagree again with you.
air mass is a very good indicator for estimating max power and at least to find out the right HFM for your tune.
even with different fuels. So according to you, ignition timing makes no difference right? Do you realize there can easily be a 150hp difference at high power outputs due to ignition timing? Have you ever mapped a car on E85?  Air mass only shows how much air is going to the engine, it does not show what you are doing with it or how efficiently you are using it. It's a good estimate on two equal engines with equal fuel type. It's completely useless for comparing engines with different compression ratio and fuel type. this engine will be running on pump gas, 98.4 oct, with a boost of ~43.5psi, and the VE will be very high.. so ive decided to find me one of those Pro-M 92:s.. with a 30 point transfersheet made and calibrated in flowbench.. which should be perfect for this build. Unless this engine has lots and lots of displacement, I think you are being overly optimistic with your power figures. |
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« Last Edit: June 24, 2012, 11:16:19 AM by prj »
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