How many of you have non recirc. bov's?

[vadem]

Ok, I know that on ka-t without an safc you need to recirculate your bov, to stop stalling, and richness. Ive heard that if you put your mass air on the pressure side of turbo say about 10'' before intercooler, and have your bov (vented) before the mass air, that it works and not cause richness etc, sorry it might sound confusing but I couldnt put any other way. Also what if you do the same w a hacked maf? Reason for all this is I love the vented bov sound esp. an HKS ssqv. Also what does IIRC mean?

Thanks let the boost be with you

[andrave]

IIRC: if I recall correctlyIts called a "blow through mafs" when you put the mafs on the pressure side, apparently it works fine but I heard some SR guys grumbling about stumbling during cold startup. Not sure on why. As for hacked mafs, theoretically it would be the same, so I think it would work, but I've never known anyone to experiment with it.

You can run an atmospheric bov on a pull through mafs, some people do and some people dont.

[Structure240sx]

my bosch bov is recirulated and still pretty loud. i was surprised when i heard it. i jsut ordered a hks ssqv witha recircualtion fitting so ill find out how loud it is then. i now know what they sound like vented into the atmosphere so i can compare

[TurboKA37]

generally you want to place the bov as close to the throttle body as possible, so for your setup to work the bov would have to be farther away from the TB. im not really sure as to why it is better to be closer to the TB but im pretty sure its so the air getting crammed into the TB plate can get dumped or recirculated quicker. so as the bov moves farther away im sure it becomes a little less efficient.

[IvoryJ30t]

its not for the throttle plate, its so the compressor doesnt get hit with the pressure surge from the throttle plate closing, and the compressed air having nowhere to go but back out the turbo.

[IvoryJ30t]

personally, if your building a new intake tract, i would place the bov on the hot side of the intercooler, and place the maf on the cold side. but then you have to splice and extend the maf wiring.

[Structure240sx]

the mafs only has like 3 wires plus from looking at it its seems like it might even reach over. ill prolyl try this when i make a new coldpipe, i dont think the koyo rad i want next summer will fit with my coldpipe

[Projex240]

Put the MAF about 6-10 onches in front of the Tb( or in that general area), and put the BOV on the hot pipe just before it dips into the fender area. Thats the most effeiciaent routing for a blow through setup.

[S14tat]

alright so let me get this straight. when you get a blow thru MAF on you car, and you put it after the compressor discharge and then you put a BOV before the MAF is the best way? since i'm not very experienced with the whole hacked MAF thing but won't the ECU freak out when the MAF sees air being pulled thru a blow thru type MAF when the boost has to travel past it to get to the BOV?

[TurboKA37]

first compressor, then comes the bov on the hot pipe, then intercooler, then MAF on the cold pipe near the TB. the ECU freak out? why? the MAF will always be reading the correct amount of air the TB sees with this setup. if you want to learn how the hacked MAF setup works there are a couple threads that explain it very well. what do you mean by freak out and why?

[MikeMurphy]

OOOOOOR you can slap on a MAP sensor and do whatever the hell you want with your BOV with no ill effects. Thats my plan for one day when I start putting this thing together.

[MikeMurphy]

I thought the MAF ran on tempuratre via voltage?

If your running it after the turbo then the air is going to be very warm and your MAF is going to give you VERY incorrect readings since it doesent measure pressure.

[ROB240]

I’ve been running a blow through setup for about a month now with an open atmosphere bov. Idles and runs perfectly. A MAFS measures air density, it doesn’t care if its pressurized or not, whether it is before or after the turbo doesn’t matter, its still metering the same amount of air. I am certainly not the first or only person to do a blow through setup on a KA, its been done before on higher hp cars than mine and worked just fine.

[S14tat]

well what i thought was since the stock MAF is a pull thru type it has to be put before hte turbo inlet. and it wouldn't work if you put it after the compressor discharge cause then you'll be pushing air thru a pull type MAF and thats why the people do a blow thru type hack in the first place. well i would guess thatt he ECU don't do anything if the MAF sees air flowing the opposite direction. cuase i know that MAP's starts making the ecu go crazy when it sees pressure above atmosphere so i would assume that the MAF is the same.

[MikeMurphy]

A MAFS measures air density, it doesn’t care if its pressurized or not,

Are you sure it doesent measure air density via air temp?

[ROB240]

Are you sure it doesent measure air density via air temp?

well since warmer air is less dense, it will still meter air correctly. my understanding of the mafs is that it heats a wire whose resistance is sensative to heat, by sending a constant voltage through it, and when air moves across this wire it cools it thus changing the resistance of the wire. so the more air moving over it the more it cools it, and also the colder/denser the air moving across it the more it cools it. this is why its called a mass air flow senser, it measures the total mass of air moving through it taking into account temperature and presure (or vacuum). i hope i didnt confuse you too much lol, let me know if that explains it for ya.

[C-Kwik]

actually, it doesn't measure resistance. It measures the voltage required to maintain the MAF hot-wire at a specific temperature. The more air that goes across the wire, and cools it, the more voltage that is needed to heat the wire up.

[Structure240sx]

that was probably the easiest to under stand explaination c-kwik. somehow it jsut clicked and made sense

[IvoryJ30t]

ok, it doesnt matter if the air is being blown thru or pulled thru. its the same thing.

also, its telling the ecu the mass of air entering the motor. it compensates for changes in temperature on its own.

the temperature of the air, and the volume of the air, and the pressure equals the mass of the air. thats the information passed to the ecu.

remember, air and fuel are a mass ratio. its 14.7 parts air to 1 part fuel by WEIGHT.

it doesnt matter what the temperature or the pressure of the metered air is, because the MAF figures it out for you and passes it to the ecu.

[IvoryJ30t]

another words, its not passing one parameter like volume. its telling the ecu the MASS of air entering the motor. thats why its a MASS AIRFLOW METER, not a volume meter or a temperature meter.

[IvoryJ30t]

its funny we got on this, because i used to do DSM's. they use a maf known as a karman-vortex meter, which measures volume. but in order to determine mass, there is a barometric pressure sensor and a temperature sensor built into the unit.

one of the upgrades is a cobra maf, which is a hot-wire unit. in order to use the hot wire maf, you need a converter box that sends a constant temp and baro pressure signal to the ecu because a hotwire maf automatically compensates for those conditions, and does not require seperate sensors.

see why the pressure and temperature dont matter? because a hot wire unit takes the whole picture and sends the mass figure to the ecu. im not going to get into why, but just accept the fact that the MAF knows whats going on.

[C-Kwik]

The karmen-vortex somehow measures a certain frequency of some sort to measure air-flow. I'm not as keen on it, but I think it measures the speed of air through it. Therefore it would need a pressure and temp sensor. Flapper door and plunger type MAF's are similar as the amount of movement the flapper door moves correlates to airspeed. As with Karmen-Vortex, it needs a separate pressure and temp sensor to calculate the actual airflow. Hotwire MAF's are the only type that can measure all parameters through only the hotwire.

[vadem]

Thanks, for the replys. Now I know that it'll work. I will post the buildup and all pics, of this setup in a few monthsfrom my project, so all you can see. Its going to be s14, t3/to4e, hacked blo tru maf, fmic, custom intake mani, and exhaust mani, 370s. Later

Vadem

[Trppen37]

dont forget...to make sure the hacked maf cold pipe is not more than 3 inches...

[j-z]

so can someone write exactly what you have to do in order for the kat to run properly with open atmosphere bov. all of these posts are just too confusing and have different information in them. i think that one detailed thread on this subject telling exactly what you have to do would be more helpful. so whos gonna do it?

[Structure240sx]

prolly on one since the info can be found on the website. it may seem confusing to u since ur new and may not know too much about the ka. sorry im really trying not to be a **** and im not jsut goin to say search either

[j-z]

youre right i am new to the ka. **** i dont even have one yet. im starting research early. i understand what everyone is talking about the maf and how it works and stuff. i totally understand that. i just havent read one post that tells you exactly what you need to do in detail to run open atmosphere. theres just bits and pieces and its like trying to put a puzzle together that you have never seen before. it would be alot easier to see exactly what you have to do in a detailed step by step write up. it should include all parts that you need and where to get them from. do you understand what im trying to get at? or if someone knows where a good write up is send it my way. thanks

[TurboKA37]

if your running a blowthrough setup just make sure the BOV comes before the MAF and you should be fine

[j-z]

so when refering to a blow through setup your talking about haveing the maf in the charge piping correct? so i basically came to the conclusion to have the maf in the charge pipe from the intercooler to the TB. and place the bov before the maf in the charge pipe from the compressor to the intercooler. so can i use my stock maf? just basically have it setup like it is in the intake but in the charge pipe? skool me!!

[andrave]

yes