FREE Air-Intake Mod: Full Details on Page 6 of this thread

[monaco_blue]

Apols - my post seems to have touched a nerve.

As far as logging frequency I remember logging post intercooler IAT on my 993 turbo simultaneously taking the data from the OBD port and by tapping into the factory IAT sensor. I found that the IAT from the OBD port was only sent one every 2-3 seconds so was not very accurate, especially in a turbo where the IAT is very much a function of boost pressure and how heat-soaked the intercooler has become.

As an aside the IAT sensor on a NA car has a significant thermal mass so won't respond very quickly. This is fine because the IAT doesn't tend to change very rapidly. The IAT sensor on a turbocharged car is quite different - it has to be to catch the high IATs that can occur at peak boost on a hot day with a heat soaked intercooler in order to prevent knocking.

[exdos]

Therefore comparing from car to car, or even road to road can be a bit variable. If Tony did his runs on the same peice of Tarmac on the same day however, awesome result!

Ed, I've seen datalogs of airflow through the MAF from 5 differentOEM Z4Ms, including my own, and they all max at around 31lbs/min like Tony's (mmm-five). I've previously posted data and graphs recorded from my own car (in a few postings before this) which now has my own modifications to the OEM air-intake and I've gutted the OEM silencers and I'm consistently seeing airflow through the MAF at the redline in 3rd gear of over 36lbs/min, and that's an increase of 16%. I think this shows that it's possible to improve airflow well beyond any atmospheric variability which will affect air density.

Apols - my post seems to have touched a nerve.

As far as logging frequency I remember logging post intercooler IAT on my 993 turbo simultaneously taking the data from the OBD port and by tapping into the factory IAT sensor. I found that the IAT from the OBD port was only sent one every 2-3 seconds so was not very accurate, especially in a turbo where the IAT is very much a function of boost pressure and how heat-soaked the intercooler has become.

As an aside the IAT sensor on a NA car has a significant thermal mass so won't respond very quickly. This is fine because the IAT doesn't tend to change very rapidly. The IAT sensor on a turbocharged car is quite different - it has to be to catch the high IATs that can occur at peak boost on a hot day with a heat soaked intercooler in order to prevent knocking.

Monaco_blue, the fact that you're a new poster and resurrected this thread made me think "here we go again!" The subject of the usefulness of the ram effect tends to cause arguments and since I'm a strong supporter I've had years of challenges on this subject on forums and I'm bored with argument about this now.

With regard to the datalogging of IATs of the Z4M: the data is only given up by the ECU in whole degrees (F or C) so the fall of 1 degree will not be shown incrementally, even if the data was polled at 100Hz, it will be polled stepwise, so you'd tend to see a few lines of say 25 degs C followed by a few lines of 24 degs C and so on when the temperature is falling in the intake under acceleration. The IAT sensor for the Z4M is incorporated into the MAF. Personally, I don't see how this really provides any problem to understanding how things work nor does it devalue the information obtained. The way I see it is: we're really lucky that we can datalog from OBDII at all, because, before, we were very much in the dark.

[pwnsweet]

Did exdos ever tell of his ramcharger II design? My guess is it's some sort of centrifugal air filtration system, coupled with an intake scoop (or two). The air pressure will drive the centrifuge, eliminating the need for a filter element and increasing air flow.

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