blowing thru AFM

[1fast200]

Hi guys,

What are the pro's and con's of having the turbo blow thru the Air Flow Meter instead of draw thru like the factory set-up?

[1fast200]

Come on people!!

[Nismo1182]

Ive seen a few set ups that way. I think the owners said, when the BOV blows off, it will still measure the air left inside the pipe rather than running rich when it blows off with the AFM before the turbo becuase the air it measure, it already calculated the fuel for it.

I have no idea what the cons are other than you might want to use a 3" 300Z TT or Cobra AFM if your using a FMIC with upgraded piping.

The stock AFM will definately be a bottle neck.

[CA19DET]

use a bigger afm, 300zx etc, it also allows you to place it where ever you want, help with intercooler piping etc... larger turbos, but the main advantage was mentioned above

[slw240sx]

ill be running blow through soon as my 300zx MAF is on

[1fast200]

Ok, nice, but where do you place the AFM? I guess that you don't want to put it just after the turbo, because it will get hot (un-intercooled) air and the wire inside the AFM can melt off, so the only otion is after intercooler/before T/B ?

What do you guys think?

[Movingviolation240]

I stuck my blowthrough on the cold pipe near the throttle body. It worked pretty well, better than a draw through with my massive FMIC. With the MAF closer to the TB you will get less 'lag' as the metered air flows into the FMIC and fills all that pipe before actually making it to the motor. I was running 2.25in hotpipe and 2.5in coldpipe with a massive front mount, so the smaller your IC and the less pipe you have the less this would be an issue.

Paul

[float_6969]

Ok, since this is on the same subject line, what are the pros and cons of MAFS setups vs. MAPS setups?

[Nyborg Garage]

I am considering this on my s13 with a ca18det engine, and t3/t4 topp mount turbo.

The car will be running nistune, so tuning should not be a problem.

But having a MAF with as little restriction a** possible will be important. Ford, VW, Audi's and most newer cars with MAF have the "heat wire" in a straight trough open pipe. But the Nissans have the '"heat wire" in a little air duct along side of the actual pipe.

How important is this duct? I have seen people with other brand cars mounting the sensor on a normal stainless 2,5" pipe.

Have anyone done this on Nissans?

[meminto]

If you are going to use the stock afm on the cold side of the setup (between throttlebody and intercooler) it may cause a bottleneck. It is more commonly performed with a Z32 afm...

It is fairly straight forward to perform this mod, however make sure you get it on a dyno to check afr's, it will tend to run a little on the lean side afterwards..

When researching afm/intake designs, I have read articles about mouting the sensor in larger diameter pipes to increase resolution. This is a path I didn't want to travel so I have no data unfortunatley....

[Nyborg Garage]

If you are going to use the stock afm on the cold side of the setup (between throttlebody and intercooler) it may cause a bottleneck. It is more commonly performed with a Z32 afm...

It is fairly straight forward to perform this mod, however make sure you get it on a dyno to check afr's, it will tend to run a little on the lean side afterwards..

When researching afm/intake designs, I have read articles about mouting the sensor in larger diameter pipes to increase resolution. This is a path I didn't want to travel so I have no data unfortunatley....

Thank you for the info.

Mounting the stock ca18det AFM anywhere at all on the engine is not an option :p

Think I will have to try and mount the sensor it self straight on a 2.5" pipe between the BOV and the throttle body on the cold side.

I do the tuning my self, and that part should not be a big problem.

[meminto]

No dramas mate, good luck with it..

I myself was going to plumb the Z32 on the cold side of the cooler, but alas I no longer can..

[iliketocrash]

as far as i know the con to having a MAS is the fact that the sensor measurements are based on the physical construction of the housing. Ergo, the MAS is usually only good for a somewhat narrow band of airflow. In other words it is possible to flow too little air or too much through the MAS and not get a very precise measurement. Where as if you use a MAP style setup, the range of air flow the system can measure is far greater but i believe lacks the level of resolution/precision you get with a MAS.

On a side note, i've had a lot of friends use the "blow through" style MAS setup on their DSMs and they would put it before the throttle body but at least 6 or 8 inches away. I was told that if the MAS is too close to the plenum that it causes erratic readings from the MAS or something. Dunno for sure, just what i heard.

[float_6969]

Holy Zombie thread batman!

[meminto]

Better searching and reviving than getting a chastising from the masses for not searching

[Nyborg Garage]

No dramas mate, good luck with it..

I myself was going to plumb the Z32 on the cold side of the cooler, but alas I no longer can..

Thanks

The best option for me would be to run MAP sensor instead, I definitely like MAP better than MAF. But I have searched alot, and I can not find an EMS that can compare with NIStune when i comes to Price, datalogging, GUI (graphical user interface), tuning capabilities, no ekstra boxes or wiring+++ I just love it So I will have to stick with a MAF then.

[Nyborg Garage]

On a side note, i've had a lot of friends use the "blow through" style MAS setup on their DSMs and they would put it before the throttle body but at least 6 or 8 inches away. I was told that if the MAS is too close to the plenum that it causes erratic readings from the MAS or something. Dunno for sure, just what i heard.

I was planing about 8-10" away from the throttle, and having the BOV 5-10" away from the MAF. But thanks for the head up, did not know that

[sjbsuperman1425]

idk if anybody said this, but for a blow through MAF setup, what if you ELIMINATED the MAF itself and just took out the sensor from the unit, and had it installed on the IC piping somewhere? that way you dont have more couplers and more chance for leaks, it looks clean, and you can do what you wish with your BOV?

its tempting to try, but im going to stick with the traditional MAF setup probably unless i get really bored (not likely)

[ganma_ca]

That's not a half bad idear there. I like it* Just make a bung or something to fit it in the ic pipes. (idk might wind up being difficult). As stated before though(under what runs your engine) A map is like + 1,000,000,000 way better:) Because if anything goes fubar w/turbo or ic pipes blow off or something stupid your car can still run n drive:) Plussssss waaaaaaaaay better for tuning!

[sjbsuperman1425]

some aftermarket intakes for SOME cars have the little "bung" so you can put your MAF sensor in the aluminum pipe, so if someone found one that fit with the Z32 MAF sensor, they could have it welded in the piping and be done with it! lol

i do like MAP alot though, i was all for it back in the day when i wanted an SR lol

i plan on getting the E-Manage later down the road, and if i ever decide to go top mount if i get bored of bottom mount or want more power, i'll go MAP because it makes Top Mount turbos WAAAYYY sexier lol. it always about the bling factor

[Fleemer]

From my understanding, the MAF just heats up the coil and the air cools it by the ammount going by.

I don't know how it adjusts itself when air is warmer/denser but I feel you should really screw around with its factory position since it was engineered that way.

On the other hand, I know the ca18det ecu (nissan ECUs in general) are very adaptive and if anyone can confirm of it working/reading well on the presurized size then I'd like to know.

I'd be curious to its accuracy and results ^_^

[Nyborg Garage]

) if anything goes fubar w/turbo or ic pipes blow off or something stupid your car can still run n drive

That is one of the most importart reasons why i want to have the MAF closer to the throttle body

[Nyborg Garage]

idk if anybody said this, but for a blow through MAF setup, what if you ELIMINATED the MAF itself and just took out the sensor from the unit, and had it installed on the IC piping somewhere? that way you dont have more couplers and more chance for leaks, it looks clean, and you can do what you wish with your BOV?

That was my plan from the start (i metioned it in the first post). Mostly becouse i thought all the Nissan MAFs had the same design as the stock ca18det maf, only bigger. But now that i see the Z32 is a "straight trough" pipe just like on Fords, Audis, and others I really don't know if it will be worth it.

IF I could use the stock sensor from the ca18det MAF it would be worth it, since it's free.

But unlike with the Z32 the ca18det MAF have the hot wire in its own tiny pipe alongside of the actual pipe, so the "bracket" for the hot wire is really short. I just don't know how that will work.

On the Z32 and other MAFs the hot wire is i the middle of the big pipe, so those would deff work well in a 2.5-3" IC pipe. But if I where to buy a Z32 I would just use it with the stock housing.

Mounting the c18det MAF on a stainless or alloy pipe would need som "advanced" fab work to get it to seal propperly, and I asume the Z32 sensor is mounted the same way?!

And BTW, the top mount turbo system would look just as sexy with the MAF on the cold sid, as with a MAP sensor That is another reason for why I am doing this.

[Nyborg Garage]

I have done a lot of searching on other nissan forums today, and it seems like the "blow through MAF" system is widely common amongst some sr20 communties.

Also I could not find any serious drawbacks with the system Everyone that was using it was really happy with it, and many had used it for a long time.

Also it seemed to need much less tuning then I had thought at first. Some said non att all, but I deff would not move the MAF anywhere without checking the AFRs.

Some used the stock sr20det MAF, but moste used the Z32 MAF (much less restriction since it is the same inner diamater all the way through).

I could not find anyone who had tried to mount the sensor it self straight on a IC pipe

[sjbsuperman1425]

I could not find anyone who had tried to mount the sensor it self straight on a IC pipe

thats because its something nobody really thinks of doing..it'd be somewhat unique in the Nissan realm i think

[Nyborg Garage]

thats because its something nobody really thinks of doing..it'd be somewhat unique in the Nissan realm i think

Well, maybe i'll just have to try it then

[themadscientist]

I have seen it done. The car was an R33 RB25DET. The guy cut the tube portion off the MAF leaving just the probe and circuit box. Then he drilled a hole in the IC piping a lil bit bigger than the probe. He coated the underside of the circuit box with RTV, slid the probe into the hole and slapped a pair of sturdy hose clamps on the MAF and clamped it down to the pipe. I raced the guy a couple of times, trust me, it worked.

[Nyborg Garage]

I have seen it done. The car was an R33 RB25DET. The guy cut the tube portion off the MAF leaving just the probe and circuit box. Then he drilled a hole in the IC piping a lil bit bigger than the probe. He coated the underside of the circuit box with RTV, slid the probe into the hole and slapped a pair of sturdy hose clamps on the MAF and clamped it down to the pipe. I raced the guy a couple of times, trust me, it worked.

That's just brilliant! And so easy. If it works I will probably fabricate something better looking later on.

[sjbsuperman1425]

I have seen it done. The car was an R33 RB25DET. The guy cut the tube portion off the MAF leaving just the probe and circuit box. Then he drilled a hole in the IC piping a lil bit bigger than the probe. He coated the underside of the circuit box with RTV, slid the probe into the hole and slapped a pair of sturdy hose clamps on the MAF and clamped it down to the pipe. I raced the guy a couple of times, trust me, it worked.

its just SUCH a good idea lol not only do you clean up the exhaust side of the engine, but it can make everything MUCH easier lol although i think i read somewhere that you need or should have a 8" straight section of IC pipe before the sensor or else it'll cause turbulance

i do think if i get bored or go Top Mount this is the way im going to go! but then i need to find a spot for my BOV if the above statement is true..

[themadscientist]

I don't advocate it. The sensor will probably not last long in a hot, pressurized, dirty environment. I just know how to do it.