MAF value = Horsepower potential
02-24-2019, 04:22 PM
#46
Rennlist Member
I'll play too 
Did some pulls on an uphill slope and collected the following from the Torque pro app. Mine is a '03 996 all stock except sport cats from Carnewal and mufflers from Fister.
91 octane pump gas in CA. A/C off.
Year: 2003
miles: 78k miles
Displacement : 3.6L
Max MAF : 252.5 g/s
Intake air temp : 102F
Ambient temp : 56F
Barometric pressure : 29.4hg
Altitude : 666ft
Max VE: 98%
Edit: more pulls. Got 312.8 g/s while intake air temp was at 77F. Not sure how consistent the max MAF numbers are. Max VE at 102%. For simplicity, I entered 3600 cc in torque (which is used to compute VE I believe.)
Did some pulls on an uphill slope and collected the following from the Torque pro app. Mine is a '03 996 all stock except sport cats from Carnewal and mufflers from Fister.91 octane pump gas in CA. A/C off.
Year: 2003
miles: 78k miles
Displacement : 3.6L
Max MAF : 252.5 g/s
Intake air temp : 102F
Ambient temp : 56F
Barometric pressure : 29.4hg
Altitude : 666ft
Max VE: 98%
Edit: more pulls. Got 312.8 g/s while intake air temp was at 77F. Not sure how consistent the max MAF numbers are. Max VE at 102%. For simplicity, I entered 3600 cc in torque (which is used to compute VE I believe.)
02-24-2019, 10:42 PM
#47
Rennlist Member
Thread Starter
02-25-2019, 03:30 PM
#48
Right. 312.8 g/s is physically impossible. Did some Torque logging and got some more believable numbers:
Coolant temp: 194 F
rpm: 7142
IAT: 91.4 F
MAF: 241.5 g/s
mph: 31 mph
VE: 100%
Coolant temp: 194 F
rpm: 7142
IAT: 91.4 F
MAF: 241.5 g/s
mph: 31 mph
VE: 100%
02-27-2019, 08:28 PM
#49
Rennlist Member
Thread Starter
Ordered this "splitter". I should be able to run Durametric and OBDII/ Elm327/Torque Pro at the same time. Should be easy to compare values since the values should be identical. https://www.ebay.com/itm/Ultra-Low-P...72.m2749.l2649
02-27-2019, 08:39 PM
#50
Race Car
02-27-2019, 09:25 PM
#51
Ordered this "splitter". I should be able to run Durametric and OBDII/ Elm327/Torque Pro at the same time. Should be easy to compare values since the values should be identical. https://www.ebay.com/itm/Ultra-Low-P...72.m2749.l2649
BTW, sadly Durametric can only read the MAF value (or any sensor value) at ~10 times per second (best case). The Torque pro probably reads the MAF much less frequently than that. especially if you log other PIDs at the same time too.
I have not monitored the max MAF values long enough to be confident about the consistency of this max MAF value for my car. The 241.5 g/s was observed in a Torque log which logged the MAF readings in time during a drive. I picked up the max 241.5 manually and saw the readings immediately before and after it are all "smooth", as opposed to a sudden spike to 241 g/s..
02-28-2019, 12:18 AM
#52
RL Community Team
Rennlist Member
Rennlist Member
I'll give it a try with my Snap-On Ethos Pro this weekend.
I need to find a low-profile OBD extension like that splitter.
It's kind of a PITA to drive with the cable run across my lap.
I keep knocking it loose with my left knee.
I wish the OBD port was on the other side of the steering wheel!
I need to find a low-profile OBD extension like that splitter.
It's kind of a PITA to drive with the cable run across my lap.
I keep knocking it loose with my left knee.
I wish the OBD port was on the other side of the steering wheel!
02-28-2019, 12:21 AM
#53
Race Car
I'll give it a try with my Snap-On Ethos Pro this weekend.
I need to find a low-profile OBD extension like that splitter.
It's kind of a PITA to drive with the cable run across my lap.
I keep knocking it loose with my left knee.
I wish the OBD port was on the other side of the steering wheel!
I need to find a low-profile OBD extension like that splitter.
It's kind of a PITA to drive with the cable run across my lap.
I keep knocking it loose with my left knee.
I wish the OBD port was on the other side of the steering wheel!
The following users liked this post:
wdb (10-16-2023)
02-28-2019, 12:32 AM
#54
RL Community Team
Rennlist Member
Rennlist Member
Could be.
The OBD port is required to be within 2 feet of the steering wheel.
Wish it could be in the middle.
That makes it a lot easier to deal with the scanner's cable.
Although the newest Snap-on scanners have a wireless feature.
But I prefer a cable, no batteries to deal with, or having to remember to recharge yet another device.
03-01-2019, 10:47 AM
#55
Rennlist Member
I'll give it a try with my Snap-On Ethos Pro this weekend.
I need to find a low-profile OBD extension like that splitter.
It's kind of a PITA to drive with the cable run across my lap.
I keep knocking it loose with my left knee.
I wish the OBD port was on the other side of the steering wheel!
I need to find a low-profile OBD extension like that splitter.
It's kind of a PITA to drive with the cable run across my lap.
I keep knocking it loose with my left knee.
I wish the OBD port was on the other side of the steering wheel!
03-01-2019, 04:20 PM
#57
Rennlist Member
Thread Starter
If you can't see the advantage in knowing this stuff, or have any interest in it, I don't know what to tell you.
The following users liked this post:
c didy (01-19-2023)
03-01-2019, 07:00 PM
#58
Burning Brakes
Could be simple changes like a new air filter to ‘the sky’s the limit’. If it doesn’t matter to you, then there’s really no point in doing it, but it could also point out impending problems, like clogged cats, etc before CEL gets lit, that should be addressed before it leads to more serious problems. Just my thoughts, and I have had this capability to do this for several years on every vehicle I’ve owned since the dawn of OBD2, but I’ve never done it before.
Maybe I’m one of those guys it just doesn’t matter to!
03-03-2019, 02:57 AM
#59
Rennlist Member
Thread Starter
Here is a link to a correction calculator using "Motorsport Standard Atmosphere" for correcting for altitude, intake temperature, humidity, barometric pressure. It uses Motorsport Standard Atmosphere, Barometric pressure isn't critical. The altitude, intake temperature and humidity are the most critical and will make the most difference. To compare data sets from different parts of the world, in different weather conditions.
Using Coopduc's data set and assuming a relative humidity of 50% for NC,and since there is no intake air temp data, assuming 75F, IAT , the correction factor is 1.136.
197.1 g/s / .75= 262.8 x 1.136= 298.5bhp
Using my data set with a relative humidity of 50%, the correction factor is 1.041
213.4/ .75 = 284,5 x 1.041 = 296.1bhp
http://www.wallaceracing.com/weather-corr.php
Using Coopduc's data set and assuming a relative humidity of 50% for NC,and since there is no intake air temp data, assuming 75F, IAT , the correction factor is 1.136.
197.1 g/s / .75= 262.8 x 1.136= 298.5bhp
Using my data set with a relative humidity of 50%, the correction factor is 1.041
213.4/ .75 = 284,5 x 1.041 = 296.1bhp
http://www.wallaceracing.com/weather-corr.php
Last edited by Porschetech3; 03-06-2019 at 10:51 PM.