Originally Posted by Porschetech3

The Mass Air Flow of an engine is directly related to the horsepower potential. The power production process all starts with amount of mass air the engine can inhale, then the DME calculates the required fuel at 12.6:1 ratio for best power. The power "potential" can be calculated by using the Mass Air Value alone,( injecting more fuel will lower power output without more air mass).

Sure there are many variables that effect the actual power output like number of valves per cylinder, combustion chamber shape, flame travel, time at TDC, rod/stroke ratio, cam profile, ignition timing, displacement, but when comparing our 996 engines those variables will be the same.

While the above variables do effect Mass Air flow, they are not something that most of us will alter, except maybe displacement with a "big bore" kit, or maybe ignition timing with an aftermarket tune for some.

So why would we even care about the max Mass Air Flow Value? Because if your Max MAF value is low, your engine does not even have the "potential" to make the desired power. If I stick a potato in one of your tailpipes, you will not have a good Max MAF value and power.

Max MAF values can be used to evaluate displacement increases, intake plenums, TB, headers, exhaust, cats, anything that has to do with air flow into and out of the engine.If on an engine Dyno and you see an increase in Max MAF value(potential), but no increase in "actual power" you will have to ask "why not !!"..Any increase in Max MAF value SHOULD also produce an increase in "actual power"...

Back in the 70's 80's we would have given our left nut for a MAF sensor to measure actual mass air flow. That kind of stuff was only found in laboratories of the manufactures. Some speed shops had flow benches for heads but that's about it. We would change cams, heads, intakes, carbs,headers in all combinations and have to go to the track to see if it was better or worse..

I tried to keep this background section short as to not stir any debate and focus on collecting data from others that may be helpful to some who are interested in this kind of stuff.

The thick film MAF on our cars is very accurate at measuring actual Mass Air Flow and can be monitored easily with a bluetooth OBDII LM327 and a Torque app on your phone. Here is my Max MAF value as displayed in Torque in grams/second. 213.4 / .75 = 284.5hp

Year: 1999
miles:174,000
Displacement : 3.4
Max MAF : 213.4 g/s
Intake air temp : 62F
Ambient temp : 57F
Barometric pressure : 28.9hg
Altitude : 660ft
Intake sys : custom short ram
Exhaust : headers, stock cats and mufflers
other mods: none

Originally Posted by EVOMMM

All I’m saying is I’ve done business with both of you guys and individually your both nice guys
but this crap turns me off and I’m sure others so both your points get lost in the toilet water
if you can’t ignore each other at least resist the urge spit flames at each
so the rest of us can digest both of your valuable information/ideas

Originally Posted by EVOMMM

It’s not the correction it’s the your tone everyone sees
so to get the info we have deal with the bickering crap
and I’m a big boy I know how to play in the playground with others

Originally Posted by zbomb

https://en.wikipedia.org/wiki/Oxygen_sensor

A variation on the zirconia sensor, called the "wideband" sensor, was introduced by NTK in 1992[5] and has been widely used for car engine management systems in order to meet the ever-increasing demands for better fuel economy, lower emissions and better engine performance at the same time.[6] It is based on a planar zirconia element, but also incorporates an electrochemical gas pump. An electronic circuit containing a feedback loop controls the gas-pump current to keep the output of the electrochemical cell constant, so that the pump current directly indicates the oxygen content of the exhaust gas. This sensor eliminates the lean–rich cycling inherent in narrow-band sensors, allowing the control unit to adjust the fuel delivery and ignition timing of the engine much more rapidly. In the automotive industry this sensor is also called a UEGO (universal exhaust-gas oxygen) sensor. UEGO sensors are also commonly used in aftermarket dyno tuning and high-performance driver air–fuel display equipment. The wideband zirconia sensor is used in stratified fuel injection systems and can now also be used in diesel engines to satisfy the upcoming EURO and ULEV emission limits.

Originally Posted by Porschetech3

Ok correction ,,, wideband just had been " introduced by NTK" but "Bosch " had not yet supplied them to Porsche for the M96 996....24 years ago.....lol...

So, again, our cars use the narrow band 02 Sensors.....

Originally Posted by zbomb

Dude - give me a break, the tone.... if you have an issue with what I said above, you're 7 ply soft... I had no need to respond after this exchange until skip decided later he just couldn't deal with being wrong.

Originally Posted by Porschetech3

. it was late last night and I didn't feel like "fact checking"at the time and thought Zbomb needed to feel like he got one..

Originally Posted by Porschetech3

But here is the Bosch Patent for the popular wide-band that every one is using and is used by all the aftermarket stand alone wide band kits... The patent was applied for in 1998 and was granted in 2004, and was first used in Carrera in 2005 on 997, and was first used in the 2001 Turbo...

https://patents.google.com/patent/DE19815700A1/en

Originally Posted by Porschetech3

Our cars have narrow band 02 Sensors ( wide band Sensors were not yet invented) .

Originally Posted by Porschetech3

Our cars did not get this because it had not yet been perfected........

Originally Posted by zbomb

First it was they weren't invented. Then it was they weren't perfected... Invented and perfected do not mean the same thing. Just a heads up.

https://rennlist.com/forums/996-foru...l#post19105420

Originally Posted by jdbornem

Sure, like growing back to the 3.6 airbox!
The 3.8 had 3.7% less injector time, but also had 4.1% less air! The result being... drum roll... 4.1% less calculated HP potential.

___________3.6______3.8_____delta
MAF(g/s)___249.7___239.4___ -4.1%
Injector(ms)__16.7___16.08___-3.7%

I'm not making final conclusions here. I'll probably do some more data collections between the two before reaching a final conclusion. There are threads here claiming that for larger bore rebuilds, the 3.8 might be a better box to use, and that certainly may be true. I suppose it's possible that I'm just limited by how much air my stock 3.6 can pump? Not sure why the 3.6 would be better than the 3.8 in any case, but like I said... more data...

Originally Posted by Porschetech3

Has anybody actually measured the cross-section of the 3.6 air box compared to the 3.8 air box ??

Originally Posted by jdbornem

Based on my measurements, I think they are the same size, but do I understand correctly that if the 3.8 was larger, then it would be reporting lower mass air flow than actual (as you say), then the engine would be run lean.
However, over time, if that were the case, I should see my fuel trim readings start to drift up to correct the AFR. Is this correct?