jcsbanks

I think this is an interesting way of looking at inlet tract restrictions. Before Evoscan was out I hooked up a gauge to the inlet pipe just after the MAF sensor and as expected recorded pressure depressions, although more than you would expect from the airflow alone. I've noted that on Evoscan the same can be logged with the barometer - it does seem to update even during a WOT pull and the numbers do seem to agree with the gauge.

Would be interested to hear what sort of pressure drops you guys are getting - mine are up to 10% of the atmospheric pressure on the stock airbox/filter, although I get a little ram effect at speed in a high gear. What about you aftermarket induction guys?

jcsbanks

Double post. Apologies.

Girlie

Is this what you mean?

RPM TPS Baro
2500 100 100
2531 100 100
2594 100 99.5
2656 100 99.5
2688 100 99.5
2750 100 99.5
2781 100 99.5
2844 100 99.5
2906 100 99.5
2969 100 99.5
3031 100 99.5
3063 100 99.5
3156 100 99
3219 100 99
3313 100 99
3375 100 98.5
3469 100 98.5
3594 100 98
3656 100 98.5
3781 100 98.5
3875 100 98.5
4000 100 98
4094 100 98
4188 100 98
4313 100 98
4406 100 98
4563 100 97.5
4625 100 97.5
4750 100 97.5
4844 100 97.5
4969 100 97.5
5063 100 97.5
5156 100 97.5
5281 100 97.5
5375 100 97.5
5469 100 97
5594 100 97
5656 100 97
5781 100 97
5875 100 97
5969 100 97
6031 100 97
6125 100 97
6219 100 97
6313 100 96.5
6406 100 96.5
6500 100 96.5
6563 100 96.5
6656 100 96.5
6750 100 96.5
6813 100 96.5
6875 100 96.5
7000 100 96.5
7031 100 96.5
7125 100 96.5
7188 100 96.5
7281 100 96.5
7344 100 96.5


It is stock piping with the Buschur intake filter.

jcsbanks

Exactly that, thanks, what boost are you running mid/top? You may find as well that under no throttle the baro was reading higher still? I think mine yesterday was 102 under no throttle, 100 at low revs full throttle, but dropping to 92 at high revs.

MalibuJack

iTrader: (5)

I actually noticed that area under the hood is a low pressure area, so its a bit starved for air under high speeds, which could explain some of what you see, when I placed my stock airbox's scoop back in that location, It was reduced a bit.. The fact that you see a measurable difference means that the MAF looks to be a bit of a restriction..

I cannot even reproduce this with the blowthrough meter I have.. Obviously there is no baro sensor in the intake tract (Its located in the control box) but just to be safe, I placed the control box in the same location as the air filter..

MalibuJack

iTrader: (5)

Lets also note that there is a 1 bar map sensor on the Intake manifold.. So i'm not 100% sure what Evoscan is reading..

jcsbanks

You mean the MAF unit's baro sensor doesn't sample from inside the inlet tract but draws from the surrounding area? I thought it did match the readings I got from the inlet tract on a gauge. Also, if it was the surrounding area why would it drop as revs increase since the stock airbox is drawing through the intake duct some distance away from the MAF sensor's baro sensor?

If it was the intake manifold one you'd expect it to peg high rather than drop?

I think the reason that the aftermarket induction kits may not gain is that we are reducing the pressure loss but increasing the air temp so the net result is similar? A nice cold air ducted bigger/smoother airbox might be nice, but I've not found one that will fit with my HKS UICP and water reservoir yet...

The APS cold air kit I tried looked as though it would get heat wash from the radiator fan as there was an open gap between there and the filter area.

MalibuJack

iTrader: (5)

No, its in the inlet of the sensor.. Just I couldn't reproduce it with my blowthrough unit because its sensor is hidden in the control box..

but your right, I would expect the same thing if we were looking at the wrong sensor.. Only in the past I was not aware that the Baro sensor itself could have been directly read by the ECU, it was always documented that it was just to offset the MAF signal.. However seeing there are Baro settings in the ECU changed my opinion.. Just never played with it on my car because it never made a difference due to my aftermarket components.

I only wanted to clarify that the Baro sensor and MAP sensor are different sensors on the car...

jcsbanks

It does seem like it might be a good way of telling if you intake is restrictive then Mine sucks but at least the air is cool. What I don't like about the stock airbox is the way the lid is quite close to the filter, and the base covers about half of the filter area. Plus the corrugations on the inner surface may deaden sound, but don't look too good for flow?

C6C6CH3vo

iTrader: (9)

The only way I can figure the MAF can interpret atmospheric psi is from the quality of kaarman output ( like if varying levels of psi change it). The unit has no such barometer like sensor on it, just a kaarman thang, temp sensor, and a bunch of modern-day radioshack-looking stuff on a card.

Where does it read psi?

Girlie

Boost is spike of 23psi, tapering to 19~20 at redline.

My baro is 101 at idle-40% throttle. Also the IAT drops under WOT.

Not sure if this helps any? I could this weekend do some logs back to back with intake filter, stock box, snorkel etc if that would help any?

jcsbanks

I don't want to put you to trouble, but this sort of logging of temperature and pressure with the various inlets would be very useful, and as far as I know new data for the community.

Girlie

No trouble at all. I enjoy doing that kind of stuff, might learn something!

Girlie

jcsbanks

Look forward to the results immensely. Thanks! I'll probably order a new intake, may as well copy yours if the results are significant. To compare, mine is 102, 100 on light throttle, dropping to 95 after spool, 92 at high RPM!

chrisw

iTrader: (2)

Here is mine from a log taken last weekend.

This was taken at sea level. the run goes from 2100 to the rev limiter.

[edit] - for reference, this is the default 03 rom provided by MJ with minor tweaks to the boost limits no fuel or timing changes have been made yet.

RPM TPS AirFlow AirTemp Baro
2188 026.275 0119.51 86.108 103.0
2188 028.235 0150.96 85.064 103.0
2250 028.627 0163.54 85.064 103.0
2313 028.235 0163.54 84.020 103.0
2375 026.275 0138.38 84.020 103.0
2406 026.275 0132.09 84.020 103.0
2406 026.275 0138.38 84.020 103.0
2469 026.275 0138.38 84.020 103.0
2500 027.843 0157.25 82.976 103.0
2531 027.843 0157.25 82.976 103.0
2563 027.843 0157.25 82.976 103.0
2563 028.235 0163.54 82.976 103.0
2594 032.549 0245.31 81.932 103.0
2688 033.725 0257.89 81.932 103.0
2750 100.000 0415.14 80.888 102.5
2875 100.000 0522.07 79.844 102.0
3031 100.000 0679.32 78.800 101.5
3281 100.000 0899.47 76.712 100.5
3469 100.000 0987.53 76.712 100.5
3750 100.000 1056.72 75.668 100.0
4000 100.000 1119.62 75.668 99.5
4313 100.000 1239.13 74.624 99.0
4563 100.000 1327.19 74.624 98.5
4406 100.000 1421.54 74.624 98.0
5031 100.000 1459.28 75.668 97.5
5281 100.000 1534.76 75.668 97.0
5594 100.000 1603.95 75.668 96.5
5813 100.000 1603.95 74.624 96.5
6063 100.000 1603.95 74.624 96.0
6313 100.000 1603.95 73.580 96.0
6531 100.000 1603.95 73.580 96.0
6750 100.000 1603.95 73.580 96.0
6938 100.000 1603.95 73.580 96.0
7125 100.000 1603.95 73.580 96.0
7313 100.000 1603.95 72.536 96.0
7438 100.000 1603.95 72.536 96.0
7594 100.000 1591.37 72.536 96.5
7563 017.647 0157.25 72.536 103.0
6594 013.725 0062.90 74.624 103.0