Best GM MAS set-up Options

[KOU In3]

I've done a lot of the reading but I'm curious of the opinions from those who have tuned with them. What do you think is the best GM MAF set-up. Basicly the options are those below:

3" drawthrough
3.5" drawthrough
3" blowthrough

Second question. To descreen or not? I would think there would be less restriction without the screens but I'm thinking the 'straighter' airflow might be better. I've read lots of opinions but no definative data there either. Anything out there from you guys that have been all over the yahoo groups?

By the way, as you might expect, this is a sheer performance question. Not interested in venting for it's own sake. I'm leaning towards a 3.5" descreened draw-through set-up at this point but could easily be swayed.

[zach]

I may not be correct but, this is my theory...

3.5 draw through would be great,

I would think blowthrough would give a more accurate reading, because it is actually meetering the air right before it goes in to the engine... so anything that affects the air, such as pressure , temperature and so on would best read right befor it gets set on fire
if you want to blow through, it should depend on your intercooler piping,

for example I have 2.5 piping, so i'm using a 3 inch, the 3.5 would not gain anything because after the sensor it goes back to 2.5 piping.

If you have 3 inch use the 3.5
or do whatever you want, it will all work!

another twist to the plot is it is rumored that the 3.5 sensor is more accurate, and easier to tune, than the 3... I don't understand how this is possible but, it's a rumor I guess

[natedogg]

I have done both the 3" and 3.5" (3.5" is my current setup) drawthrough and both seemed equally tuneable and accurate.

There is still a debate as to which setup (drawthrough or blowthrough) is better. Zach's assessment for blow-through is fairly common and makes good sense. I'll go ahead and add a different point of view to the table. One thing going against blow-through is that the pressurized air after the turbo has a stronger laminar flow. This can theoretically make the blow-through setup less accurate for two reasons. One, since the high pressure tends toward the outer edge of the pipes, going abruptly from a 2.5" pipe to 3" MAF sensor can cause some nasty turbulence and cause more or less air to be read than should. Two, since the higher pressures tend toward the outer edge of the pipe, that air on the outer edge is moving faster than the air toward the center of the pipe. This too can theoretically give false MAF readings.

That being said people, like Kris, have done blow-through and have had great results. Other people have tried switching to blow-through and have had not so great results. Buuut those people may not know what they are doing. I think it just comes down to personal preference, how much work you want to put into it, and how loud you want your BOV to be.

[AWD DSM 1]

Nate, Kris and Marcus should be the authorities on this one. I think each is running a slightly different setup, all with good results. I'll be running a 3" drawthrough when I finally get my translator. I think this setup will be pleanty big for my application, and feel it's almost overkill for my goals. Main reason I want the Translator is to add some fuel adjustability to my setup, and give me the abbility to run slightly larger injectors without problems.

Let us know what you end up doing, and how it works!

[zach]

your smart nate...
I would not have realized the turbulence that would be associated with the blow through setup.

but would it really be any worse than the sensor in a drawthrough setup?
I figured that the air is going to be changed, when it passes through the intercooler and turbo, than when its sucked through the filter.

i guess either way works great, as long as it is installed properly

[KOU In3]

The ramchargers unit arrived today! For a Wed order I have to say I'm impressed at the quick arrival. 5 days including the weekend where UPS won't deliver and it's in my hands. Planning on trying a 3.5" draw through to see how it starts out.

[natedogg]

but would it really be any worse than the sensor in a drawthrough setup?
I figured that the air is going to be changed, when it passes through the intercooler and turbo, than when its sucked through the filter.

Well the difference comes in the fact that the air after the turbo is pressurized (positive pressure/greater than atmospheric). This is what causes the high pressures to tend toward the outside of the pipe causing faster flow near the outer part of the pipe. The air on the drawthrough side of the turbo is being sucked through (vacuum/less than atmospheric) which tends to create more even air velocities across the pipe diameter. The air also flows more evenly in draw through because it is coming (at least in my case) directly from a cone/cylindrical filter which is designed to create even airflow. In blowthrough the air is most likely transitioning from a 2.5" pipe to a 3" MAF back to a 2.5" in pipe which is quite a bit more turbulent than the drawthrough case.

[SCCA Stang]

i was looking at the gm maf sensors at advance auto (where i work part time) and they have different part numbers depending on what car they come from. what gm car's maf works the best on a dsm maf/translation mod???????

by the way, they run aprox. $45 + tax there.

[natedogg]

I'm pretty sure, as long as its a 3" or 3.5" three prong plug GM MAF it will work. Anyone who has questions regarding the translator and/or gm mafs should check out http://autos.groups.yahoo.com/group/dsmtranslator/.

The archives and files have a lot of good info.

[SCCA Stang]

thanks nate!!!!!