What would happen....

BAC5.2 · Post by **BAC5.2** » Fri Apr 23, 2004 7:36 pm

I have no idea what that engine is in, but it looks like your average, everyday boosted 420a in a 2nd gen DSM

vrg3 · Post by **vrg3** » Fri Apr 23, 2004 8:26 pm

Heh, Jason, you're probably right.

THAWA · Post by **THAWA** » Sat Apr 24, 2004 12:30 am

oh, thought you were talking bout something else

boosted5speed · Post by **boosted5speed** » Sun May 02, 2004 11:28 pm

Actually, if im not too mistaken, that car no longer has a stock "maf"

as the 1g DSM's have a what i think is called a vaf (vane air flow) and that car is most definately a 1g (pop-ups)
If anything its running a Maf-translator and a GM 3" maf sensor off of an impala SS or other lt1 powered car. With the GM maf and the maf-t you can use either blow through or draw through settings on the maf. Hope this helps.

<= other car = 1g dsm turbo and have had several.

boosted5speed · Post by **boosted5speed** » Sun May 02, 2004 11:29 pm

Oh and with the stock maf setup, it most certainly does NOT like being vented to atmosphere.

BAC5.2 · Post by **BAC5.2** » Sun May 02, 2004 11:51 pm

Yea, that is a GM 3" MAF. Apparently, it does work for venting to the atmosphere. I saw it done in person.

createnew · Post by **createnew** » Tue May 25, 2004 10:14 am

Yeah you guys are right, is a GM MAF. The stock DSMs came with a Carmen Vortex type sensor which just estimates air flow. A lot of DSM guys get the GM sensor and put it behind the turbo, intercooler, and BOV. One of the reasons they do this is to vent to atmo, another is to lean or richen the fuel mixture with the translator, plus it's way more accurate.

One thing you would have to do to use the MAF post turbo is to filter the air comming from the PCV, or just vent it to get rid of blow-by. If we were to run enough pipe to a FMIC, like in that pic, we could probably do this on our turbo Legacys. But all that piping is a waste. I may eventually try this, but I am planning on running an Air-to-Water IC setup (way more efficient.)

By the way, I am running a BOV (atmo) on my Legacy, but the only reason I can get away with it is because I have an Auto. I've had no problems except letting off of a powerbrake while still stopped, (it tends to rich out and stall.)

azn2nr · Post by **azn2nr** » Thu Apr 28, 2005 4:51 am

bringin this topic back from the dead because fat has put their stock maf's in the charge pipe and have reported good results

http://forcedairtech.com/wrx_stage2.html

edit for link with pics

scottzg · Post by **scottzg** » Thu Apr 28, 2005 6:05 am

wtf? None of this makes any sense....

Stage II Turbo Kit for the WRX and STi comes with a GT30R Turbo. This is a 5 PSI system with about a 60-80 HP gain... All of our kits contain everything to Turbo Charge your vehicle...Where as the factory exhaust is much too small for Turbo applications.

Do they know that the wrx and sti are already turbo? And how do they get a 60hp gain by dropping the boost 9 or whatever psi?

And of course i have to question the merits of installing a 500hp turbo on a 2 litre car and running a fmic... but then im no fun.

azn2nr · Post by **azn2nr** » Thu Apr 28, 2005 6:22 am

thats for the rs kits

vrg3 · Post by **vrg3** » Thu Apr 28, 2005 6:43 am

sammydafish also put his MAF sensor in the charge pipe:

http://bbs.legacycentral.org/viewtopic. ... 326#115326

jilo860 · Post by **jilo860** » Mon Feb 13, 2006 6:36 pm

its called a blow through setup. im currently doing this on my 95 240sx. it really does improve throttle response and clarity of measurements from all the people ive talked to about it. as far as having the space for it 240 - easy, lots of room legacy turbo - hard as hell unless you are planning on doing a front mount. there is just no room to do it. from what ive read and learned from people the maf must be at least 4 inches from the throttle body, or when the tb closes air will revert and disrupt the maf readings.
if anybody pulls this off on a legacy i have got to see that. cant think of any way to get that done on my legacy while still being in the realm of stock.

BAC5.2 · Post by **BAC5.2** » Wed Feb 22, 2006 5:59 pm

As of my last post in this thread (more than a year ago), I've gained a lot of knowledge about turbocharged cars.

Blow-through has proven to be extremely beneficial on high-output STI's and such.

With TurboXS, we set up a lot of blow-through MAF's, and it's had great results.

We mostly do it on rotated mount cars, so we can package things more efficiently.

To do so does require lots of computer tweaking though, but I'll talk to the guys at TurboXS about it next chance I get.

sammydafish · Post by **sammydafish** » Thu Feb 23, 2006 7:46 pm

I'm running the MAF if blow through mode. Works awesome. This is an old pic. I've swapped to a new turbo and redid all the hoses. New pics comming soon. Still works the same way though. I'm on the NA engine management though, which doesnt compensate for increased air temperature with compression. I've got to imagine the turbo management as some algorythm to compensate for it. Since I'm in blow through, I don't need it (MAF reads the actualy mass of air after compression and intercooling)

BAC5.2 · Post by **BAC5.2** » Thu Feb 23, 2006 8:20 pm

My only wonder is what it would do to your MAF voltage.

I'd think it'd be similar. I mean, the same amount of air that comes INTO a turbo also must come OUT of the turbo.

Post by **Legacy777** » Fri Feb 24, 2006 12:52 am

It should be the same. The mass of the air should not be changing as it goes through the turbocharger.

vrg3 · Post by **vrg3** » Fri Feb 24, 2006 2:05 am

That's neat, Junior. So the sensing element can deal with the higher temperature range after all... What have you done with the PCV setup?

sammydafish · Post by **sammydafish** » Fri Feb 24, 2006 2:56 am

PCV is routed in before the turbo, so there's always vacuum

the systems goes in this order:

Filter -> PCV -> turbo -> IC -> BOV -> MAF -> IAC -> TB

vrg3 · Post by **vrg3** » Fri Feb 24, 2006 3:46 am

Hmm... so some blowby is getting into the MAF sensor under certain circumstances, but it's works anyway? Interesting.

Maybe the sensor is able to burn off whatever blowby lands on it?

douglas vincent · Post by **douglas vincent** » Fri Feb 24, 2006 6:30 am

Brydon of rallitek is running a post maf as well and it has helped him alot. I am going to switch as well next week and see how it turns out for myself.

sammydafish · Post by **sammydafish** » Fri Feb 24, 2006 3:30 pm

Oil on the MAF became a problem when I toasted my turbo and dumped about 4 quarts of oil into my IC. It was only a problem when it got that bad. I don't really get any blowby from the motor at all. Until my turbo took a dump, there was no liquid oil residue at all in my pipes. I did have a catch can on it for a while but yanked it as the hoses were getting in my way.

If blowby is a problem, then just install a catch can. If it's really a problem, then it's time for a rebuild.

boro · Post by **boro** » Mon Feb 26, 2007 8:07 pm

So has any one done this running a Saab IC? It seems interesting, but short of placing the MAF only 4 or 5 inches from the turbo outlet, I see no way to run it with out dumping nothing but hot air through it.
I also has an atmospheric BOV so that's why I am curious.

skid542 · Post by **skid542** » Mon Feb 26, 2007 8:37 pm

One thing that may/may not have already been mentioned is turbulence. The pics of the blow through MAF's have the MAF after the intercooler. By running the air through some piping and through the intercooler, a lot of the smaller turbulences have already damped out. If you put the MAF right after the turbo I would suspect that you will have some problems with getting a good reading on account of all the turbulence coming out the turbo.

Just my $0.02 which doesn't answer your question but still seemed worth mentioning.

BAC5.2 · Post by **BAC5.2** » Wed Feb 28, 2007 6:15 am

Don't run the MAF pre-intercooler. It'll cook the MAF. and the car won't want to idle for shit.

biggreen96 · Post by **biggreen96** » Fri Apr 27, 2007 1:48 am

I think I want to try this out. However the way my system is setup is that the BPV/BOV would be installed after the MAF. Sammydafish puts his before. But it seems like that wouldn't matter very much. Thoughts?

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What would happen....