MAF position: Draw-thru vs. Blow-thru

J30_VG33ET · Post by **J30_VG33ET** » Sat Nov 15, 2008 11:40 am

I was hoping to get some input from the group on actual experience running and tuning one layout vs. the other. There are plenty of opinions out there... How about some good data? Anyone tuned back-to-back configurations? How did your calibration change? Did the MAF reliability vary?

Thanks.

Bernardd · Post by **Bernardd** » Sat Nov 15, 2008 11:53 pm

I've done both recently. The setup where on different cars but the same engine, same mafs, same injectors, similar turbo's, fuel pumps, one a 240z the other was a 280z. The drawthru took about an hour to tune to 18-19psi. The blowthru took all day and I still wasn't happy with it. I found that at low load/rpm the blow thru maf sees much more air causing the car to go rich. I corrected most of it by tuning the vq map and bit on the fuel map. The top end was very similar to the drawthru setup afr wise.

J30_VG33ET · Post by **J30_VG33ET** » Sat Nov 22, 2008 1:05 pm

Was the plumbing similar? Specifically the lead-in and discharge from the meter?

Anyone else out there have any experience?

Bernardd · Post by **Bernardd** » Sat Nov 22, 2008 1:37 pm

the blow thru had 2.5 to 3" adaptor front and rear to allow the maf to be connected and the filter directly on the turbo.

Fusion Ed · Post by **Fusion Ed** » Sat Nov 22, 2008 10:42 pm

I have done one RNN14 with blow through on a Z32 MAF. I wasn't very happy doing it this way, but it did work very well.

Took me about the same time as normal.

21FOX21 · Post by **21FOX21** » Sun Nov 30, 2008 5:13 am

Has anyone broke a z32 maf in the blow through configuration? I want to do blow through but I am not sure if it will explode of anything because of the pressure.

TSL · Post by **TSL** » Sun Nov 30, 2008 12:40 pm

I haven't seen one obviously break from too much pressure with up to 25psi of boost.

I have always been skeptical of this as they are not designed to take pressure. But then i was thinking recently that they are designed to work under reasonably strong vacuum, and surely that would fall under the same/similar design parameters as for boost pressure.

Temperature is more likely to be a problem.

nissangts · Post by **nissangts** » Mon Dec 08, 2008 12:28 pm

Hey guys what are the benefits with the blow through MAF. As I understand it nissans come with a draw through MAF set up, but why would you want to switch. Does it increase to power potential?

1SIKZ31 · Post by **1SIKZ31** » Sat Dec 13, 2008 3:27 pm

With the Z32 MAF, I have noticed that when doing a boost leak test, at around 8-10 psi the mass air flow "box" at the top of the MAF starts to rise up and OFF the MAF "pipe", which made it leak a TON of boost!
I used a few large zip ties around the assembly of the MAF and clamped the mass air flow "box" down, I fully got rid of my problems (now only leaks a TINYYYY BIT)

The Benefits are:
You can run them after the intercooler so heat wouldnt be much of an issue.
Increased throttle response (Noticeably better)
If a Intercooler pipe blew off (which happens often for me) I can still drive it home normally because the MAF is AFTER the leak point...
I can run a blow off valve BEFORE the MAF and that "lean hesitation" and car cutting out problems fully goes away since its not metered air that is escaping.
The downsides:
Possible boost leak point if you don't buy the correct adapter for it (buy metal adapter)
Can't think of any other downsides?

Dark Diver · Post by **Dark Diver** » Mon Dec 15, 2008 7:50 am

When doing a boost leak test on a Z32, you should never go above 5 psi b/c some parts, such as the MAF, never see positive pressure.