jcsbanks

Thanks! I think I'll try a few variations:

HKS panel filter vs Stock panel filter
Airbox lid on vs off

And also try a few different boost levels.

I'm not a fluid engineer, but I know from Bernoulli's effect that the airflows we're talking about in a tube like the stock intake would be expected to have a pressure drop - that is after all what creates the flow. I'm after the marginal increases/decreases in pressure drop from extra power and torque, and with different intakes.

If anyone has an HKS Kansai setup that would also be particularly interesting as although expensive it looks the best to my eyes since it has a low restriction filter and nice cold ducted pipework.

The stock setup with a new top duct could also be nice, but I do wonder about the base of it - the MAF sensor sits in about half the box's width just under the filter as I said.

MalibuJack

iTrader: (5)

Keep in mind that everything is calibrated to the flow of the MAF.. which is why the car runs leaner when you use an aftermarket intake.. Basically by increasing the size of the intake pipe, you slow the speed of the airflow through the sensor..

jcsbanks

Is there any reason why the pressure and temperature sensors would be inaccurate at the point of measurement though? I want the highest pressure and lowest temperature at the MAF sensor for my chosen intake.

Girlie

I will log the different applications tonight. Yesterday it rained all day, so I was unable to do the test. I am planning on:

Buschur intake
Buschur intake with snorkel
Stock setup
stock setup with lid off

Any other suggestions just let me know.

Girlie

jcsbanks

Sounds superb Girlie! Really look forward to the results, will be most interesting and helpful.

bez_bashni

2MalibuJack- U cannot put stock evo mav to the bigger pipe - its not subaru -It is sqare and has a big plastic sqare cells structure after the honneycomb.

The idea is good - but the stock baro sensor have to be calibrated.Im not sure the 98 is really 0.98BAR

Currenly we see according to logs posted above, that stock filter eats about 7% of power ..

P.S. Again F##ing MAF hz limit - we need to find load cell.
If we assume that mut translates the same load as used in tables- it is a 2-byte value running from 0 to 1000

jcsbanks

I think MalibuJack has put in a different MAF sensor in blow through config?

Re the scaling of the barometer... maybe it is a bit steep, but the readings are similar to previous readings I saw on a gauge - ie 0.1 bar depression under full power.

bez_bashni

Ok- I'm glad to hear someone done that-so we can trust the baro calibration.

BTW -the formula for calculating power loss on inlet restrictions/temperature

1.The ambient temperature is needed. Can be aproximately measured by the car temp sensor if the cold car is standing in the shadow with opened hood. (just turn the ignition-init evoscan and measure temp and pressure) obviously is lesser the least temp measured during the run.

so the formula
POWER LOSS (RPM)%= 1-measured presuure (atm ,BAR or KPA)/ambient presuure (atm ,BAR or KPA)*((ambient temp (F)-32 )/ 1.8)+273)/((measured temp (F)-32 )/ 1.8)+273) *100%

I won't be surprised if stock setup (box+filter will kick *** BIG BRAND's cost $$ setups.(especially cone filteres without box)

bez_bashni

Made excel calculator .

jcsbanks

Thanks. Would the perfect inlet with zero or insignificant restriction expect to have a small pressure drop anyway from Bernoulli's effect though - just from being in a moving air stream? A chemical engineer previous sent me a calculator to do this, will see if I can find it later.

MalibuJack

iTrader: (5)

I do have a blowthrough MAF setup using a ford cobra MAF sensor, AIT and BAro sensors are external to the unit therefore need no calibration. (They are located at the air intake)

And you can easily put the MAF onto a bigger pipe on the intake, the stock intake is about 2.5" and the MAF is about 3".. most aftermarket intake pipes are 3" in diameter, however their increased size decreases air velocity through the metered portion of the sensor which in turn causes it to read lower. It would also reduce the pressure differential you might see because of it, the lower the velocity the lower the bernoulli effect it would have passing the Baro sensor, and therefore should alter the reading less but should still be measurable. However It may not indicate any less restriction in the MAF, just measurably lower air speed.

bez_bashni

Perfect question - I just was thinking about it .
I was looking at barometric compensation table and wondering -why do the have it COMPENSATION (BAROMETR,RPM). It have to be COMPENSATION(BAROMETR,AIRFLOW) due to bernulli effect. The higher airflow - the lower K we use for scaling baro due to bernulli (baro shows us lower pressure than it actually is due to the airflow high speed ).
So the questions.
1. What are the actual scaling of baro table (is it really rpm dependant-or is airflow)
2. What number do we have in our log RAW sensor data - or already corrected .

Im gonna to try putting the resistor in the sensor's place and see...If revving my engine i'll receive the different data on the same resistor - it has correction - if the same data-raw number..

bez_bashni

I mean U cannot put stock evo karman vortex sensor to the other pipe. I planed to do this -but it wont be stock sensor anymore. The design of the karman-vortex box so complicated that i'm not sure i'll work normally just in pipe. U're probably using maf tranlator from the regular hotwire maf. In the howire U can not worry about the pressure in the maf-just the temperature- but in karmann mav i'm not sure that if U'll increase the pressure by 2 in the mav with the same air speed (as it happens in blow-tru config)-it'll proguce the same amount of vortexes as it will produce if the doubeled speed with the constant pressure..Also the aerodynamic of the box is critical as i know....

MalibuJack

iTrader: (5)

Understand that your original comment wasn't as clear, but you are correct, you cannot use a karmann sensor as a blowthrough, it will not work for several reasons, most of which you already stated..

Also, the converter box i'm using has a baro sensor in it, but its obviously not used to offset the karmann value, but only to get the base pressure to operate from (elevation)

I do know back in the first get DSM Days that the blowthrough setup using the stock VAF (a karmann sensor is a volumetric airflow sensor) was attempted on some first gen Eclipse GSX, and you never heard much more about it..

The ford cobra sensor is indeed a variant of the hot wire sensor, only its less prone to condensation and humidity than other sensors (earlier GM sensors are ones I can think of) and therefore why I chose to run it. Instead of explaining my whole setup, just do a search for my thread using "Blowthrough MAF" as keywords..

Now back on topic.. The baro compensations are exactly what your describing.. They are used to compensate for anomolous readings, one of them being the lowered pressure experienced under higher air velocities past the sensor, since the sensor's measuring surface is perpendicular to airflow, it causes a slight negative pressure and therefore would read lower.. Unfortunately it may not make a good measure of restriction since altering the intake pipe diameter does have an affect on the velocity of the airflow..

I have experienced the breakdown of the signal where you will get anomolous dips in the frequency on occasion, that is caused by turbulence that momentarily breaks down the aerodynamics inside the sensor and the shedder bar design either stops moving, or flutters at a rate not relative to the airflow, when the Honeycomb becomes deformed, the airflow can shift direction slightly also causing turbulence..

What it comes down to is the size of the MAF itself is large enough to handle quite a bit of airflow (as much as a 3" pipe can ingest) however the metered portion itself becomes prone to anomolous readings at very high air velocities.. So an upgraded intake may have no benefit with the stock turbo, in fact it becomes a detriment, but with an upgraded turbo, air velocity is lower so the sensor should read more accurately until the velocity outpaces the MAF's ability to measure it.. So far that number has been roughly 2200hz or about 450whp.

fsugatorbait

iTrader: (16)

Ill post my datalog with the Helix intake w/snorkel. Going off memory I didnt see the baro fall below 98 IIRC.