Talk about BOV's here
- Thread starter Robert Viehweger
- Start date
Shitty picture, but for now that's all I have. This is not my car, but the EXACT SAME Perrin Blow-Thru-MAF Boost Tube is installed and configured like mine.
I don't think it's too uncommon, but it's not something you see everyday either. Some are under the impression that it is difficult to tune, but from what I understand, tuners who are familiar with this setup often prefer it. I've seen maybe 2 other STi's in this configuration. If you look around online, you can find others that use it.
I don't know what companies offer this besides Perrin. Since I have a Perrin FMIC, I noticed the option to purchase the Blow-Thru boost tube.
I believe it was ~$225, which is a little steep in my opinion, but oh well...
I believe it was ~$225, which is a little steep in my opinion, but oh well...
HolyCrapItsFast
Drinks beer!
It is more common than you might think. It is a good configuration if you don't want to be restricted by stock design. You just need to make sure that you have laminar flow prior to the MAF and that can sometimes be challenging.
The one reason I choose not to employ this method when other solutions are valid, is because of one thing that NO ONE is considering when they employ it.
To calculate the mass of air you need three key measurements... Temperature, Flow and Pressure. The MAF sensor itself contains the sensors to measure temperature and flow but the pressure is measured by the Barometric Pressure sensor (not the MAP sensor like you would think). Keeping the MAF in the stock location is no problem because all three measurements are taken pre-turbo. Move the MAF post turbo, and now your MAF calculations are off because the pressure is still being measured pre-turbo. Now the tuner has to compensate somehow. If you live in a relatively consistent climate, you may not notice much of a difference from day to day, but in changing climates, the difference from day to day can be drastic. I have not found a way around this so I use it only if I have no other choice.
You should be able to see this in your fuel trims from day to day. Check it on a hot summer day and then compare it to a cold winter day OR from a dry sunny day to humid stormy day. I'm pretty sure you will see the differences. If not then I will eat my words. :lol:
The one reason I choose not to employ this method when other solutions are valid, is because of one thing that NO ONE is considering when they employ it.
To calculate the mass of air you need three key measurements... Temperature, Flow and Pressure. The MAF sensor itself contains the sensors to measure temperature and flow but the pressure is measured by the Barometric Pressure sensor (not the MAP sensor like you would think). Keeping the MAF in the stock location is no problem because all three measurements are taken pre-turbo. Move the MAF post turbo, and now your MAF calculations are off because the pressure is still being measured pre-turbo. Now the tuner has to compensate somehow. If you live in a relatively consistent climate, you may not notice much of a difference from day to day, but in changing climates, the difference from day to day can be drastic. I have not found a way around this so I use it only if I have no other choice.
You should be able to see this in your fuel trims from day to day. Check it on a hot summer day and then compare it to a cold winter day OR from a dry sunny day to humid stormy day. I'm pretty sure you will see the differences. If not then I will eat my words. :lol:
Thanks George! :tup:
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