Different MAF (g/s) readings on different intakes, despite making same power.

[brandon19]

Hey all, I was just curious if anyone would understand why this happens, or if there is something I am not understanding here. So bare with me.

Essentially I have a 3" intake inlet pipe with a 3" intake MAF sensor housing on the end. I was flowing around 350g/s at 6500rpm at 21psi. I got curious and got a 4" intake MAF sensor housing made to see any differences. I took off my 3" MAF sensor housing and replaced it with the 4" one, keep in mind I am still on the 3" intake inlet pipe. I adjusted the MAF calibration once again so actual and desired AFRs matched, except this time, at the same boost and similar rpm point, it was flowing around 380-390g/s according to the log, but I can tell you it 100% didn't feel any different to when I had the 3" intake MAF sensor on. IDCs were still the same as before despite flowing 30-40g/s more and power on VD was still fairly similar, so why the higher airflow readings? Normally I would say the MAF calibration was wrong, but the AFRs are on point, so I can't see where it went wrong.

It isn't really an issue at the moment, I have just switched back to the 3" intake MAF sensor housing for the time being, but was wondering if someone was able to explain why this was the case. Does it have something to do with the lower MAF voltage readings? Normally around 4.5-4.7v on the 3", on the 4" it was around 3.6v, but again I wouldn't of thought that would matter.

 

[Enki]

Simple; trims.
After the first pull (in a genwon at least), the ECU will compensate for fueling/mafcal being off, and come back down to expected levels. Also, these cars tend to get more power from timing rather than fueling, like in most PI applications, so perhaps you either have flat timing or are hitting higher loads which is pulling timing, thus more drastically removing power vs the increases you'd see from the extra airflow.

Ideally, this is a conversation you should be having with your tuner, as it may need a touch up tune on the new intake.