tjts1

I have 3 maf housings on hand, a 2 V6 68mm and one 74mm from a V8. I've tried various combinations of maf screen, no maf screen, larger maf etc. In the end the best setup was the stock 68maf with both screens. I have done some porting on my spare elbow by smoothing out all the sharp edges, removing one of the 2 guide vanes and knife edging existing vane.
https://i.imgur.com/hzDXLUn.jpg

The car already has a 74mm V8 TB and and 19# injectors which were probably the 2 most effective mods on my 3.2. The next thing I want to try is relocating the maf in a W210 intake tube away from the throttle body. Driving this car around with a torque app I realize that this giant plastic airbox on top of the engine heat soaks really badly in slow traffic or after parking it for a few minutes and it takes forever to cool down. I'm starting to think its a compromised design compared to the early M112 and M113 in the W202 and W210 which simply had an intake tube and the airbox mounted on the side. I have insulated the bottom of the airbox which actually helps with a lot with the heat soak problem.

speed43

You got different results from my testing. I got better results with the top honey comb screen on and the silver screen under it off. For the elbow I brushed on fiberglass resin. This help out quite a lot to keep heat out. I'm sure there's better stuff but I had plenty of this so I used it. If you can please share pictures of where you moved the maf, if you do end up doing that.

tjts1

I think plastic grid only is the only setup I haven't tried yet. I'll give that a shot. I was thinking of using this intake setup from a 210.
https://i.ytimg.com/vi/0xvI8EHvbQQ/maxresdefault.jpg
It would need to extend the MAF wiring and figure out another airbox. I think this setup will be a lot less prone to heat soak because theres less surface area and plastic exposed. Also the maf sits in the middle of a long relatively straight tube which might negate the need for the plastic grid. Anyway, this idea is still a bit far off, I haven't given up on the big airbox yet.

Fatz

It will be another week or 2 before I reinstall the strut brace, but when installed it makes slight contact with the airbox/engine cover.

insame1

Check out the setup on the clk320 also. Some folks in the W208 forum did dyno testing and it had the highest numbers if I remember correctly.

tjts1

I tried the plastic grid only setup and it does indeed flow the most air. The problem I ran into is the engine stumbles for a second when I accelerate from idle. I put the metal screen back in and the stumble went away. The W208 runs a completely different airbox and intake tube to the TB with the MAF in a different position. I think it might actually have some advantages over the W203/W209 airbox setup but I haven't had a chance to test it yet.

I'm using the Torque app hooked up to my OBD2 port to test each modification. I do 5 runs before and 5 runs after on the same road under the same conditions to test each modification.

The first modification I did was swapping in a 74mm throttle body from an M113 replace my 68mm M112 throttle body. That was an immediate improvement in throttle response and it dropped 0.3 sec from my 0-60 time. From my testing the 74mm throttle body is by far the most effective, easiest cheapest modification on the M112. The improvement in throttle response in normal driving is night and day and for $25 (fleabay) you can't beat it.
https://i.imgur.com/03tcv6i.jpg
https://i.imgur.com/oNVjAvw.jpg
https://i.imgur.com/jDG2oyy.jpg

The next thing I tried removing the screens from the stock 68mm MAF. The car ran fine about 90% of the time but I would encounter a random stumble when accelerating from the stop. With no MAF screens the car actually became marginally slower to 60. I think most of that loss was just off idle when I tip in the throttle. I gave it a week to give the ECU to adapt to the MAF. No change, eventually I got annoyed and put the screens back in.
https://i.imgur.com/4FmoXxs.jpg

I picked up a 74mm MAF and elbow and ported the elbow by taking off one of the guide vanes and smoothing out all the sharp edges. I tried the ported elbow with the 68mm maf and couldn't really tell a difference. Maybe it makes a difference on the V8 but I really didn't see any change on my 3.2.
https://i.imgur.com/YRCvEWl.jpg

Next I removed the sensors out of the 68mm and 74mm MAFs, turns out they're exactly the same part number.
https://i.imgur.com/RzAY7Rw.jpg

Then tried the 74mm V8 MAF. Immediately the car slowed down. 0-60 was up to around 8.5 sec, 1.5 sec slower than stock. Both O2 sensor banks were reading lean throughout the run. When I looked at the recorded MAF sensor data I realized that the 74mm maf was only showing 140-150g/s airflow while the 68mm maf was in the 170-180g/s flow rate. The air demand of the engine doesn't change but going through a larger diameter pipe its slows down going past the sensor and consequently reduces fuel.


74mm MAF. Note the peak number.
https://i.imgur.com/Fcwfv1J.png

68mm MAF.
https://i.imgur.com/BjCYOFc.png

So the larger MAF is obvioulsy less restrictive but it reduces fuel. Eventually I found a hack around the problem.
http://www.samnaprawiam.com/poradnik...bosch-bmw.html
Translate to English and have a read. Basically you drill a progressively larger hole in the back of the MAF sensor until the flow reading from the sensor in a 74mm housing matches the flow reading from the same sensor in a 68mm housing. I can't do this type of fine tuning on the road so break out the shop vac and icarsoft.
https://imgur.com/II9Vffl
Plug the MAF into the car's wiring harness, hook it up to the shop vac, turn the key to position 2.
https://i.imgur.com/67ShMx2.jpg
Use icarsoft to monitor the "HFM-SFI" voltage output.
https://i.imgur.com/jMleHQ0.jpg
The 68mm MAF was showing 3.42v and the 74mm MAF was around 3.10v in stock form at the same shop vac flow rate. Take the sensor out of the MAF and drill a small hole in the back, test, enlarge the hole, repeat. I went through this process 4 times before the 74mm MAF signal matched the 68mm MAF signal and you end up with the MAF on the left.
https://i.imgur.com/vOjaA3X.jpg
The end result is the car is perfectly derivable, no stumbles, excellent throttle response and it does 0-60 in 6.4 sec consistently. Theres a lot of info floating around on this and other forums about modifying the 3.2 intake. Most of it is coming from one tuner who started out on the Chrysler crossfire forums. Some of it is right, a lot of it is wrong. To recap:
74mm TB: YES!
Removing the guide vanes from the intake elbow: MEH not really
74mm MAF: NO. If you're willing to put a bunch of time and effort into modifying and tuning it then yes but the payoff is questionable.
Larger airbox: YES!
This car is now also running on 19# injectors from a V8 (0.2 sec quicker) and gutted rear cats. I'm willing to dick around and experiment on this engine because I'm planning a 3.7L M112 swap out of an M350 in the near future. I hope somebody finds this information useful.

Cheers

wokdwoki

speed43

You're very welcome and thanks for your kind words.

I have two more I'm going to make if anyone is interested. Just email me or send me a pm. Thanks.

Crankturner

*Bump

Been a while - Are these still available??

Thanks

speed43

Yes still available, just send me an email or PM and I will take care of you. Thank you for your interest.

Btw, I'm out of the stock boxes, if any of you should be interested in buying my modded boxes, please let me know in advance so I can order some. I don't like having to many around unless I have buyers.

Thanks.
Speed43
Custom Air Boxes For:
W202 C43 Amg
CLK500
C55 Amg
And a few more....
And soon C63 Amg

GezaBMX

Hi tjts1,

Do you have to use a "V8" elbow, MAF and airbox if you switch to a 74mm throttle body?