Thread: Decided on Blowthrough

I've decided go with a blow through setup and had a question or two to make sure I got my facts straight.

• MAF needs to be at least 12" from Butterfly
• BOV needs to be at least 6" from MAF
• I need to reseal the E60 MAF (this applies to other similar mafs)
  

Now I was thinking about doing the E60 MAF which is 3" and two 3" to 2.5" couplers. But then I thought about turbulence issues that may arise from the size differences.

Would it help to say do it like this:
Intercooler --- BOV --- 3" diameter 6-10" long -- MAF --- 3" to the throttle body.

Throttle body is 2.75, so having a bigger pipe might mean a leak around the throttle body, but a good 3" to 2.75" coupler should take care of that.

What do you guys think?

I like your thinking. I think a bunch of people do it that way.

The mafs with a screen on them will work a lot better in areas of higher turbulance. The Screen promotes good laminar flow.

I would go about where you said. 12" away from the TB, and try to keep it in an area away from bends, and reductions.

I got a 2.75" coupler on my VE TB to a 2.5" for the piping. It should work great.

Have you thought of putting the BOV on the hot side?

I guess I should add that a friend of mine switched from Blow-thru to pull-thru last week and he says the response isn't as good, but the car is more consistant and he swears he picked up hp from a better tune.

I think maybe his car is just feeling better because he had intermittent issues with it. I drove it and sometimes it would feel quick, other times it would feel really slow. I have been running an N62 maf for a while and no issues here.

i m running a blow through also & the car feel for responsive.....personally im happy with it i ran 13.7 with 12 lbs boost street tires no launching...... just easy..

Thanks, I think most people just use silicon reducers. I'm thinking using 3" should help low end before boost build up



Great on the MAF screen I got a few by now haha. My current MAF has shaved adapter piece since I had no room for a MAF adapter. But I got a quality piece from OEM (Overkill guys), so I can keep the screen on.

I will definitely make sure it's a straight shot for as long as possible Since I've rotated my battery I should have more working space.



I've thought about the BOV on the hot side, but my hot side is not long and since it goes through the radiator support.

I hear a better throttle response with Blowthrough, that will be a plus, but I'm also concerned about the post MAF boost leaks. Since I can't weld up all of my piping, I have to use a lot of couplers, which means it can leak etc.

Oh I forgot to mention, I am planning on recircilating the BOV even with blow through, and having the breather still be wired up to the turbo intake to reduce blow by.

I did a little researching and it seems like the reason no OEM cars do blow through is because of oily blow by. Over time the oil will dirty up the MAF thus making it not work too well. Thus the valve cover breather is always after the MAF.

Running an external oil catch can should reduce the oily blow by.

Well I just looked at different positions of the MAF and BOV, and it's going to be a little hard to find a perfect spot. Not quite enough space...

Now when measuring the 12" from throttle body does that mean 12" from TB or butterfly it self, also is that to the MAF as a whole or the middle of the maf where the sensor part is?

Measurements of how far the MAF needs to be

Looks pretty good to me.