Dyno Science: "CAI" Box vs Open Cone Intake
- Thread starter SlowNA06
- Start date
TEK310
New member
i dont know what you meant by, the MAF is heat dependent? it does not read temp. ours happens to be a hot wire maf, it reads a +or- of voltage at the heated coils, which is changed as air flows by it, cooling the coils.
forgive me if thats what you meant
just finished tuning a 2010 camaro at school on the dyno with hp tuners, believe it or not you have to recalibrate your maf for intake changes.
we put on a giant open cone intake and it leaned out from 12.2 to 13.3. gained no power, just 1tq. now we recalibrated the maf to read the air changes and we gained 10whp
it all comes down to tuning. straight up cooler air makes more power, its a chemical fact. you stick on a intake that takes in ambient air over the 150+* air under the hood, your pcm will be able to allow more timing advance which equals free power.
thats all there is to this thread. colder air is better, provided you have the required CFM for your application and your MAF is tuned properly.
if you want a good comparison. use the same filter and tube length and diameter, one with a box and one without. do not change CFM(filter type or pipe length or diameter)
forgive me if thats what you meant
just finished tuning a 2010 camaro at school on the dyno with hp tuners, believe it or not you have to recalibrate your maf for intake changes.
we put on a giant open cone intake and it leaned out from 12.2 to 13.3. gained no power, just 1tq. now we recalibrated the maf to read the air changes and we gained 10whp
it all comes down to tuning. straight up cooler air makes more power, its a chemical fact. you stick on a intake that takes in ambient air over the 150+* air under the hood, your pcm will be able to allow more timing advance which equals free power.
thats all there is to this thread. colder air is better, provided you have the required CFM for your application and your MAF is tuned properly.
if you want a good comparison. use the same filter and tube length and diameter, one with a box and one without. do not change CFM(filter type or pipe length or diameter)
Rico
New member
The MAF calibration is affected by drastic changes in ambient air temperature...like 80F from fender well vs. 150F from under the hood. Along as you're tuned for it...
So the MAF calibration needs to be changed in the winter versus the summer?
Where are the coefficients in the PCM to correct for changing IAT in terms of MAF calibration?
Rico
New member
Remember we're splitting hairs here.
What would you do if you're doing some serious drag racing? Would you run the same MAF calibration at 40F as 110F ambient temperatures?
If you can convince me that a hot wire MAF can account for it then I'll leave it be.
Air Flow and Mass Sensing Devices
Hot film can account for it.
Seems we have hot wire which requires IAT sensor nearby for air temp correction.
Either the PCM performs the correction using the engine IAT sensor or the MAF has an additional sensor and performs internal correction.
cold wire?
http://www.pcmforless.com/index.php?option=com_content&view=article&id=126:speed-density-sd-vs-mass-air-flow-maf-&catid=34:tuning&Itemid=56
http://www.fixya.com/cars/t4371840-need_clean_replace_mass_air_inflow
wire is maintained at 200* above ambient? Thus always in check?
More pointed info:
http://www.wellsve.com/sft503/Counterpoint3_2.pdf
Hot film can account for it.
Seems we have hot wire which requires IAT sensor nearby for air temp correction.
Either the PCM performs the correction using the engine IAT sensor or the MAF has an additional sensor and performs internal correction.
cold wire?
http://www.pcmforless.com/index.php?option=com_content&view=article&id=126:speed-density-sd-vs-mass-air-flow-maf-&catid=34:tuning&Itemid=56
http://www.fixya.com/cars/t4371840-need_clean_replace_mass_air_inflow
wire is maintained at 200* above ambient? Thus always in check?
More pointed info:
http://www.wellsve.com/sft503/Counterpoint3_2.pdf
Last edited:
Rico
New member
[h=3]To reinforce what TEK310 says about MAF calibration I post the following. I know it's not particular to our application but it gives a reasonable explanation of why changing intake geometry throws the MAF calibration off.
I think we give the hot wire MAF way to much credit when it comes to accurate volumetric calculations under extreme conditions like delta ambient etc. This is most definitely why serious drag racers run in speed density. You just can't count on the MAF.
Reference: Mass air flow - S4wiki
MAF housing diameter[/h]
Cross sectional area is given by
where D is the MAF housing diameter in mm. (e.g. 88mm, 90mm, etc.)
Since the stock cross sectional area is
(73 being the stock MAF housing size in mm), the increase in MAF (g/s) in %
A strong S4 running stock K03s, MAF, and fueling uses approximately 260 g/sec of air.
To calculate velocity, we convert the g/sec into
(volume of air per second) by dividing by 1225
(density of air at sea level).
We then divide by the cross sectional area of the housing (
).
So we get
I think we give the hot wire MAF way to much credit when it comes to accurate volumetric calculations under extreme conditions like delta ambient etc. This is most definitely why serious drag racers run in speed density. You just can't count on the MAF.
Reference: Mass air flow - S4wiki
MAF housing diameter[/h]
- MAF signal has an absolute top end reading of 5 volts. So have to scale MAF if we want more HP (since more HP means more air will be passing through MAF).
- To keep the signal under 5 volts for the maximum air flow, we have to make the diameter larger. This will make the signal smaller for a given air mass flow.
- For a given mass air flow:
- air velocity goes down with cross sectional area
- cooling capacity goes down with cross sectional area or diameter?
- voltage goes down with diameter?
- MAF reading therefore down with square of diameter and with crossectional area
- more air means we need more fuel - larger fuel injectors, higher pressure FPR
- how to determine MAF housing diameter vs injector size and fuel pressure (fuel flow).
Cross sectional area is given by
where D is the MAF housing diameter in mm. (e.g. 88mm, 90mm, etc.)
Since the stock cross sectional area is
- AWE actual dimensions are 77mm (inlet) to 100mm at sensor. It reads roughly equivalent to an 84mm-86mm MAF, but the response isn't exactly equivalent at all airflow magnitudes.
A strong S4 running stock K03s, MAF, and fueling uses approximately 260 g/sec of air.
To calculate velocity, we convert the g/sec into
We then divide by the cross sectional area of the housing (
So we get
Thats not really why they run speed density.
HPTuner experiments: MAF vs SD comparison
They're both very accurate methods, but one is faster and the other measures actual instead of using theoretical.
http://www.pcmforless.com/index.php...-mass-air-flow-maf-&catid=34:tuning&Itemid=56
SD has a faster transient response and removes MAF as an airflow restriction.
MAF is able to compensate for smaller modifications granted the air/fuel models are correct.
HPTuner experiments: MAF vs SD comparison
They're both very accurate methods, but one is faster and the other measures actual instead of using theoretical.
http://www.pcmforless.com/index.php...-mass-air-flow-maf-&catid=34:tuning&Itemid=56
SD has a faster transient response and removes MAF as an airflow restriction.
MAF is able to compensate for smaller modifications granted the air/fuel models are correct.
Rico
New member
Good info there on the first link. The data proves that speed density is more accurate with a lower correlation coefficient and standard deviation and that's on a stock vehicle. One thing I would like to say is that he sure didn't need some fancy statistical analysis to see that the outliers were caused by AFR. He could have just looked at the raw data!?!?!?! Looks like this guy dramatizes a bit but still a great writeup.
I would love for this guy to do the same analysis on a highly modified drag car. I think the MAF correlation coefficient would be much worse than SD with respect to theoretical cylinder mass.
I would love for this guy to do the same analysis on a highly modified drag car. I think the MAF correlation coefficient would be much worse than SD with respect to theoretical cylinder mass.
13aceofspades13
New member
i may be late too comment and no one will probably see my comment but thats ok, i would like too put in my input on this.
these results do not suprise me with a few HP difference which wont even be noticeable with this car, a Cold air intake is almost pointless with a car with forced induction. why? beacuse the friction of the supercharger is creating heat, not only that the air being compressed gets hot! so all that effort getting a little colder air is being thrown out the window beacuse the supercharger is compressing and heating up the air...
it would be worse with a turbocharged car! not only is the air being heated up beacuse it is being compressed, not only is the turbocharger creating friction heat, but ALSO it is being driven buy exhaust gas which probably makes the turbo quite hot does it not? would this not make the air hot too? with a turbocharged car the air is compressed and heated buy the Turbocharger, then cooled down and condensed buy the intercooler... therefore a cold air intake would be pointless, if you want colder air go with a better inter cooler set up.
it also depends on what cold air intake set up you have, some cold air intake set ups have the cone filter stuffed into a box that does not allow much room for the intake too breathe, some cold air intakes have set ups with lots of bends and lengthy piping the air must pass through creating restriction, so once again you will probably see better results with a short air intake with a large open cone air filter...
your best results for cold air intake will probably be with a N/A car with a cold air intake set up that genuinely seperates the cone filter from the engine bay allowing it too breathe cooler air than the engine bay, yet with as little bending in the intake pluming and still allowing a large cone filter... also allowing enough room for the filter too breathe, this will probably point more favorable towards the cold air intake, otherwise yes you will see better HP from a Open cone short air intake...
ALSO!
the HP gains from most After market intakes are not major, hardly within that 7-10% HP increase that is needed for noticeable performance gain, there are better ways too get power, they just get more costly.
these results do not suprise me with a few HP difference which wont even be noticeable with this car, a Cold air intake is almost pointless with a car with forced induction. why? beacuse the friction of the supercharger is creating heat, not only that the air being compressed gets hot! so all that effort getting a little colder air is being thrown out the window beacuse the supercharger is compressing and heating up the air...
it would be worse with a turbocharged car! not only is the air being heated up beacuse it is being compressed, not only is the turbocharger creating friction heat, but ALSO it is being driven buy exhaust gas which probably makes the turbo quite hot does it not? would this not make the air hot too? with a turbocharged car the air is compressed and heated buy the Turbocharger, then cooled down and condensed buy the intercooler... therefore a cold air intake would be pointless, if you want colder air go with a better inter cooler set up.
it also depends on what cold air intake set up you have, some cold air intake set ups have the cone filter stuffed into a box that does not allow much room for the intake too breathe, some cold air intakes have set ups with lots of bends and lengthy piping the air must pass through creating restriction, so once again you will probably see better results with a short air intake with a large open cone air filter...
your best results for cold air intake will probably be with a N/A car with a cold air intake set up that genuinely seperates the cone filter from the engine bay allowing it too breathe cooler air than the engine bay, yet with as little bending in the intake pluming and still allowing a large cone filter... also allowing enough room for the filter too breathe, this will probably point more favorable towards the cold air intake, otherwise yes you will see better HP from a Open cone short air intake...
ALSO!
the HP gains from most After market intakes are not major, hardly within that 7-10% HP increase that is needed for noticeable performance gain, there are better ways too get power, they just get more costly.
I personally believe tha open cone made more wheel HP( I won't even get into tha error of margin, af ratio, and other variables) bc of yes more airflow. BUT I'm assuming( don't say it) Tha runs were open hood runs? Us LS1 guys learned a LONG time ago that open hooded runs made more hp, cuz of better airflow BUT.... Give me tha 30-40 cooler inlet temps on tha street "with similar flow of course," and we'll see your extra 2HP on tha dyno give up close to a tenth to me in a drag race. And I WONT even mention tha added benefit of less KR from tha cooler inlet temps.
Happy Boosting
Happy Boosting
blueguy
The Blue One
WarStryker13
I break things.
He really wanted to post his 2 cents. Lol
