NefMoto

Hi guys. I have a problem with my 1.8t blow through setup. I didn't have space for draw through and didn't want to run alpha-n, so i implemented blow through after intercooler with oem bosch sensor. My intake piping is 63mm, stock 70mm maf sensor maxed out at 210 g/s. So i made custom stainless maf housing - it is 63mm on both ends, but in the maf sensor area it is 76mm. I got it to work almost perfect, but it maxed out at 270g/s. I can't make bigger housing because of lack of space, so... Is there any way to "trick" this sensor? I heard somewhere that resistor can be added between 2 pins, and it should increase metering range. Don't want to spend 220$ on HPX maf, unless i have to...

Blow through is a very bad idea because it is downstream from PCV and turbo and it will get contaminated with oil and read wrong (low).
I would re-think the whole approach.

Thanks prj. I dont have oil recirculation system, made a custom catch tank for it and it bypass gasses into atmosphere. Turbo is fine, i don't see any oil in the piping. I really like the driveability of blow through, it responds very quickly and i dont have to mess with dv piping. Is it really not worth it?

Put hitachi MAF from B5 S4, with 76mm it will be enought for 350+ g/s

And the car smells like shit ewww :D
OK for dragrace, I hope you don't daily that.

This will be not like this forever.

There is literally zero difference in "response" for the MAF. It does not matter one iota where it is.

I'd rather run SD (not alpha/n) than blow-through.

Also the 63mm->76mm->63mm is pretty dumb too, it will not work like you think it will.
There are two types of Bosch sensor, one with standard range and another with extended range. Extended range sensor is used for example on RS4 MAF, but also on some 2.5 TDI and certain 3.2 VR6 models.
You're probably using the standard range one.

IIRC the standard range insert is:
F 00C 2G2 040
And the extended range is:
F 00C 2G2 047

On newer MAF's Bosch stopped printing the number, but if you have an older one you can verify which insert you have. The code is not on the MAF housing, it's on the insert itself.
Using the Hitachi MAF is also possible, it is about the same as the Bosch extended variant.

If you cannot make a reliable intake system for your turbo, be it due to space of whatever constraints, then you need to run a speed density system for decent control IMO.

Thanks for your answers guys, appreciate it. I'll try with extended bosch or b5 hitachi. Depends what will i find at my local shop :D Should be fine for now. Currently running a pulsar 3071, and i couldn't fit the draw through even with 180 bend aiming for the stock airbox space. The maf itself was fine, but there wasn't any room for air filter. For spring the plan is to install 3568, so guess it's the time to extend my knowledge in ASM...

Or lighten your wallet, as I will have all the stuff up at that point.

Tbh it's a pain in the arse to implement properly and also a pain to tune. MAF is much easier.

hello,

is this something you are still planning?

Yes, I'm working on it in spare time I get from logger.

i used a pmas blow thur in 2.5 piping and it worked very nice, the maf i used was specifically designed for blow thru and came with data curve to input, you have to tween it a little bit. the pmas sensors have a much larger range of air flow reading. my blow thru setup was on a mk4 12v vr6 ecu