Page 1 of 1
Stock Turbo Legacy MAP Sensor Data
Posted: Sun Jun 14, 2009 4:08 pm
by Legacy777
I put together a quick spreadsheet on the response curve of the MAP sensor along with Todd's test data.
http://www.main.experiencetherave.com/s ... p_data.xls
The thing to note is that stock MAP sensor is really able to accurately read 16-17 psi. The response curve of the sensor is linear. As you start to get closer to the end of the range it can measure, that curve is no longer linear.
Posted: Sun Jun 14, 2009 7:55 pm
by BSOD2600
Very interesting. Guess it make sense (and more proof) why Revtronix stage 2 is limited to 17 PSI.
Posted: Sun Jun 14, 2009 8:40 pm
by Legacy777
That, and probably more so because the MAF is probably also maxed out.
Posted: Sun Jun 14, 2009 10:00 pm
by BSOD2600
The JECS MAF is maxed around 17PSI? What's the next MAF upgrade to compensate for that?
Posted: Sun Jun 14, 2009 10:26 pm
by gijonas
You know,that makes me ask something ive wondered before.Why do i see the MAF as always being rated by PSI?.This doesnt makes sense to me as i would think that it would depend entirely on displacment combined with rpm or volume of an engine-no?
17 PSI in a 2.0 is a different volume of air than 17 PSI in a 2.5 and volume is what measured by the
MAF right?
Sorry for going off track.
Posted: Sun Jun 14, 2009 10:28 pm
by JDMath
gijonas wrote:You know,that makes me ask something ive wondered before.Why do i see the MAF as always being rated by PSI?.This doesnt makes sense to me as i would think that it would depend entirely on displacment combined with rpm or volume of an engine-no?
17 PSI in a 2.0 is a different volume of air than 17 PSI in a 2.5 and volume is what measured by the
MAF right?
Sorry for going off track.
your right! maf should be should be rated by CFM
Posted: Sun Jun 14, 2009 11:15 pm
by SLODRIVE
gijonas wrote:You know,that makes me ask something ive wondered before.Why do i see the MAF as always being rated by PSI?.This doesnt makes sense to me as i would think that it would depend entirely on displacment combined with rpm or volume of an engine-no?
17 PSI in a 2.0 is a different volume of air than 17 PSI in a 2.5 and volume is what measured by the
MAF right?
Sorry for going off track.
Here's what I understand the MAFs are rated for as far as airflow before they max out: The Hitachi MAF, around 155 g/s, the JECS about 220 g/s. You're right, the MAF only cares about the volume of air going through it, regardless of what's downstream. Hope that helps.
[/highjack]
Posted: Mon Jun 15, 2009 2:23 am
by Legacy777
Sorry, I should have clarified what I meant.
The JECS maf is probably only good to that psi with whatever turbo revtronix is "specifying" for stage 2 chip.
I have my doubts that the JECS MAF will tolerate much more than Revtronix's stage 2 setup. But I could be wrong.....
Posted: Mon Jun 15, 2009 5:02 am
by 93forestpearl
gijonas wrote:You know,that makes me ask something ive wondered before.Why do i see the MAF as always being rated by PSI?.This doesnt makes sense to me as i would think that it would depend entirely on displacment combined with rpm or volume of an engine-no?
17 PSI in a 2.0 is a different volume of air than 17 PSI in a 2.5 and volume is what measured by the
MAF right?
Sorry for going off track.
True, but turbo size and efficiency play a massive part in airflow as well.
People tend to think in terms of psi on turbo cars for some reason that still eludes me. Boost pressure bares little relevance to how much power someone is actually making.
Pressure is only relative on the same motor with the same turbo.
End rant.
Posted: Mon Jun 15, 2009 6:20 am
by smh0101
gijonas wrote:You know,that makes me ask something ive wondered before.Why do i see the MAF as always being rated by PSI?.This doesnt makes sense to me as i would think that it would depend entirely on displacment combined with rpm or volume of an engine-no?
17 PSI in a 2.0 is a different volume of air than 17 PSI in a 2.5 and volume is what measured by the
MAF right?
Sorry for going off track.
Generally people are talking about at what psi the MAF maxes out with a given turbo.
For instance.
On a stock Legacy Turbo with an ej22t wiht the vf11. the stock Hitachi MAF maxes out at 14psi.
BUT on my car... ej22t with a vf24. The stock MAF maxes out at probably like 9psi because of the massive amounts more air that the vf24 sucks in.
As for the JECS
I know that Doug was modifying them to be used up to like 25 (I believe) psi on a t3/t4. I may be wrong on what exactly it was flowing out to. But it was something crazy like that.