jlert

Curious what headers you have?
I have 200 cell cats, but still have stock headers on my 997.1 C2S, so while I'm interested in upgrading my headers I wonder if doing one of either headers or high flow cats already maximizes the MAF power potential.
Then again maybe MAF power potential remains unchanged but more power is available to the wheels? idk...

delirium45

OEM sport headers, same as you... you can kinda see them in my 'build thread' here: https://rennlist.com/forums/performa...l#post18631791

jlert

Love your build thread, I've subscribed
Nice headers, are those X51?
Mine do not look like those though, I have the oem stock C2S headers that are like a shorty 3-into-1, like the ones pictured here:
https://rennlist.com/forums/996-foru...4-996-a-3.html

delirium45

Pretty sure they're not X51 ... i've seen the spec sheet for this car's build and it doesn't have that option... but now you've got me curious!

jlert

@Porschetech3 Where did you have the MAF housing made?
I am interested in doing a custom project like that, to match my 997.1 C2S stock housing diameter.

Porschetech3

This was about 15 years ago, I measured the stock air box / MAF housing to get all the critical exact measurements and made a 3D drawing of just the housing portion, then added the connection for the "Sound Enhancer" and the Dual Cone Filter..

Then transferred the 3D drawing to the on-line E-Machine Service in the .stl format with all the dimension and metal material specs.... E-Machine then sends this to all their partnered machine shops for quotes..

Then you will get a number of quotes from machine shops and I picked one that I liked out of Michigan and had him make me a dozen of them...

This is a good way to get certain custom parts made if you don't have someone already, or if your guy is just covered up with work ...

pete95zhn

Few notes.

1) Measured MAF values are valid only if the MAF itself is new or nearly new. They do deteorate when they age and will thus be off. If your MAF is original it will be indicating ~10% less than the actual airflow is. This happens without any CELs or stored faults, but may be shown in fuel trims. I've had several 997.1 turbos for tuning and when datalogging stock car the worst had airflow of ~1200 kg/h. MAFs were changed and airflow magically returned to ~1370 kg/h, which btw equals stock 480 hp.
2) If you use logger that has a logging frequency less than 5/sec you might lose the peak MAF / RPM. Something like 1/sec will cause different values on every run, even if environmental conditions are equal. More is better here, unfortunately Durametric is quite crappy and it's the best commercially available so far. For newer ECUs we use VehiCAL and it can log 30-40 different variables at 10-20 Hz.
3) When logging use the highest gear you dare and preferably run uphill to get the engine loaded. Some cars / ECUs even restrict engine's max output on lowest (1-2) gears, so it's better to use at least 3rd. In Mexico.
4) @sealevel logged mass airflow converts to manufacturer's announced hp by g/sec / 0.8 or kg/h x 0.35. OTH logged maf reduces with increasing IAT, so for best numbers run when air is cold and engine is not heatsoaked.
5) MAF sensor must be calibrated to the housing it's used in. In other words if one changes housing's size from the original the ECU programming must be adjusted accordingly. Or the engine will run poorly.
There must not be any airleaks between MAF and intake valves, or the engine will behave oddly with high fuel trims.
If MAF and injectors are new & stock and still fuel trims are excessive there's a leak in the system.

Porschetech3

@pete95zhn I agree with all said....thanks for dropping in....

BTW did you use to come in the 996 thread? or did I use to go over to the 997 thread...lol

delirium45

Just got the car on the dyno... and the best run file was 332.99 ... so this calculated power is pretty darn close !

Porschetech3

Yes it is , and works on the simplest of Physics.......less air = less power.....more air= more power..

I remember a time when all Hot Rodders would give their left nut for an accurate/simple air flow meter like our modern MAFs....even Pro track rats who would be at the track every time the gates were open, because elapsed time, as accurate as it is, has so many other variables...

Mike Murphy

Not according to my wife when it comes to the fluid between my ears.

zbomb

Would be awesome if you could post the graph and mod list in the dyno thread here https://rennlist.com/forums/996-foru...s-allowed.html

delirium45

I'll do that.

wdb

I've recently been doing some data collection on the targa using a Durametric as we go through the (remote) tuning process with FSI. It got me thinking about this thread, and about what sorts of *potential* numbers I might be seeing. I have some of the data needed and can probably get the rest, but what I don't have is the Wallace Racing correction calculator. Unfortunately that site appears to be down altogether. At least for me; I'm getting 404 errors. Does anyone have an alternative calculator?

Absent one of those, I've been seeing a lot of folks simplifying the process down to MAF g/s times 0.8. That's a ballpark number obviously, but using a standard value like that would at least give us consistent comparisons.

EDIT: Never mind! The Wallace Racing site hasn't been updated for secure browsing (https:// versus http://). Drop the "s" and the pages come up. Caveat emptor, yada yada.

Now to go do another run or two using different collection criteria...

Porschetech3

Yea, I would be interested in seeing some FSI big bore MAF flow numbers vs Stock MAF flow numbers also......thanks for taking the time to collect these...