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Is this a 3.6? or larger? Do you feel this is accurate or a spike/glitch? What OBDII/software device are you using?
Is see your in Florida, so altitude will be near sea level.
04 c4s. Stock 3.6. Only bolt on's like fabspeed intake and exhaust and a RSS underdrive pulley. All other mods are suspension and wheels. Plan on adding ipd plenum and gt3 intake at some point. Readings stayed consistant over the hour drive. Using torque pro and a bluetooth dongle. May grabe my snap on verus one day to get a better graphing display. I doubt the refresh rate on the bluetooth is worth a damn.
04 c4s. Stock 3.6. Only bolt on's like fabspeed intake and exhaust and a RSS underdrive pulley. All other mods are suspension and wheels. Plan on adding ipd plenum and gt3 intake at some point. Readings stayed consistant over the hour drive. Using torque pro and a bluetooth dongle. May grabe my snap on verus one day to get a better graphing display. I doubt the refresh rate on the bluetooth is worth a damn.
Ahh, the Fabspeed intake, could you measure the inside cross-section of the area at the MAF sensor? I'm suspecting it is smaller than the stock cross-section of the calibrated Porsche stock MAF housing.
I have no problem with the designing and installation of different intake systems, and have done so, but they MUST have the same cross-section area at the MAF sensor or a specifically calibrated MAF sensor for the housing size. Otherwise the g/s will not be accurate. Smaller housing size will show more g/s than actual, larger housing size will show less than actual g/s.
I suspect this is why FSI does not approve of any aftermarket intake systems.
If we fix 241.5g/s for the 3.6 and adjust the 3.8 number with atm. pressure and temp, the 3.8 should get 250g/s (relative to the 3.6 under similar conditions).
So the 3.8 sucks in ~3.5% more air than the 3.6 at about 6.6k rpm.
If we fix 241.5g/s for the 3.6 and adjust the 3.8 number with atm. pressure and temp, the 3.8 should get 250g/s (relative to the 3.6 under similar conditions).
So the 3.8 sucks in ~3.5% more air than the 3.6 at about 6.6k rpm.
Nice !! I got a 6.1% increase for the 3.8 after MSA correction
241.5 x 1.106 = 267.0 g/s (MSA correction, 660ft,96.8F,50% humidity)
244.25 x 1.161 = 283.5 g/s (MSA correction, 660ft,116.6F,50% humidity)
Nice !! I got a 6.1% increase for the 3.8 after MSA correction
241.5 x 1.106 = 267.0 g/s (MSA correction, 660ft,96.8F,50% humidity)
244.25 x 1.161 = 283.5 g/s (MSA correction, 660ft,116.6F,50% humidity)
283.5 - 267.0 = 16.5 / 267.0 = 0.061 x 100 = 6.1%
Thanks for pointing out the MSA correction factor. The elevation was actually at 144ft. From the MSA calculator, I got 1.083 and 1.135
241.5 x 1.083 = 261.54 g/s
244.25 x 1.135 = 277.22 g/s
=> 6.0%. Close enough because the actual cc were 3,596cc for the 3.6 and 3,824cc for the 3.8 and that's 6.3% increase in displacement.
Thanks for pointing out the MSA correction factor. The elevation was actually at 144ft. From the MSA calculator, I got 1.083 and 1.135
241.5 x 1.083 = 261.54 g/s
244.25 x 1.135 = 277.22 g/s
=> 6.0%. Close enough because the actual cc were 3,596cc for the 3.6 and 3,824cc for the 3.8 and that's 6.3% increase in displacement.
For those using the Torque pro app, my experience is you cannot rely on the "max MAF" recorded. It may record the spurious excessive values, which are physically impossible. If you use logging to log the rpm, MAF, IAT etc, and manually inspect the logged values to pick up the max, you will get a much more consistent maximum.
Obviously couldnt pay to much attention while um....moving at a higher rate of speed. But 2nd gear pulls get up to 265. 3rd gear @7k hit 286 Maf g/s. Reset multiple times and repeats same results. Tried with snap on verus and same results. Have not checked the fabspeed diameter at the maf yet.
Obviously couldnt pay to much attention while um....moving at a higher rate of speed. But 2nd gear pulls get up to 265. 3rd gear @7k hit 286 Maf g/s. Reset multiple times and repeats same results. Tried with snap on verus and same results. Have not checked the fabspeed diameter at the maf yet.
Yes this is definitely interesting !! Please measure the ID of the MAF housing when you get a chance so we can confirm. Also what was the Intake Air Temperature and humidity at the time of these pulls? They can make a big difference..
For those using the Torque pro app, my experience is you cannot rely on the "max MAF" recorded. It may record the spurious excessive values, which are physically impossible. If you use logging to log the rpm, MAF, IAT etc, and manually inspect the logged values to pick up the max, you will get a much more consistent maximum.
Is your logging showing spikes? Or does it just move up smoothly then smoothly tapers after the max..
Yes this is definitely interesting !! Please measure the ID of the MAF housing when you get a chance so we can confirm. Also what was the Intake Air Temperature and humidity at the time of these pulls? They can make a big difference..
just emailed fabspeed asking the ID.
not sure of intake temp. Wasnt looking for it. But ambient temp was 63 degrees and car was just started minutes before this run. Couldnt tell ya humidity either. But it was dry out side and night time. Weather app says 50% relative humidity if that is any help.
not sure of intake temp. Wasnt looking for it. But ambient temp was 63 degrees and car was just started minutes before this run. Couldnt tell ya humidity either. But it was dry out side and night time. Weather app says 50% relative humidity if that is any help.
Ok yes that helps. These are near perfect conditions that need hardly any correction. Near seal level, near 60F has no correction, and 50% humidity only makes about a 2g/s ( 0.010) correction, so we just need to confirm the ID of the Fabspeed which I suspect to be around 3.250in..
Last edited by Porschetech3; 03-19-2019 at 09:16 PM.
Density of air @96F = 1.144 kg/m^3 (1 atm and 50% humidity)
Air flow rate @7,000 rpm = 3.596L/6 x 3 x 7,000/60 = 209.8L/s
Therefore, mass air flow rate = 209.8 x 1.144 = 240g/s
One will need a turbo or serious ramp air/intake tunning to get higher than this number under the same conditions.
Yes I agree,I'm sure our engines are well over 100% VE at max torque (4600rpm 3.4 and 4250rpm 3.6) and probably hold pretty close to that even up till 7k thanks to the tricks of vario-cam and the intake tuning flaps on ram air tuning.
If you look at the 4.0 RS, it can pull over 390 g/s at 8250rpm with its dual vario-cam and 2 intake tuning flaps ( I have watched it on a PIWIS at Barber Motorsports Track). That's some serious VE !! That's Turbo VE on a NA motor..All this magic happens ABOVE the head gaskets also, all the goodies in the bottom end just keep it from going "boom".
My calculations for the 4.0 RS engine pulling in 390 g/s is 124% Volumetric efficiency at 8250 rpm..
Last edited by Porschetech3; 03-19-2019 at 03:23 AM.
Did a few pulls on my 2002 986 3.2 about an hour ago. Car pulls strong for a 3.2, good torque down low..And I agree with Ahsai, logging is better than recording, just don't put but two or three PID's at a time though, use RPM , MAF , then do others on a separate log.
03-17-2019, 04:32 PM
