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Afm Mod When Maxed Out (has Any One Done This) Rb25

RB SANDY

By RB SANDY,
in Engines & Forced Induction

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RB SANDY Rising Star

RB SANDY

Posted
Posted

You cut the sensor out of the std rb25 AFM and you put the sensor in to a 3in pipe because the std one is 2.5in so this means that less air will go past the sensor,has anyone done this before.

dontfeelcold Experienced

dontfeelcold

Posted
Posted

Similar to what Autospeed did except they used a seperate bypass pipe then the digital fuel adjuster to get the A/F mixtures correct.

In theory it should work the same way, just don't damage the AFM hotwires!

R31Nismoid Grand Master

R31Nismoid

Posted
Posted
You cut the sensor out of the std rb25 AFM and you put the sensor in to a 3in pipe because the std one is 2.5in so this means that less air will go past the sensor

umm... no it doesnt

have you looked at an AFM before?

You'll see that changing the diameter wont affect it at all as the AFM wire is in the middle of the AFM itself.

The amount of air going isnt going to change

RPR33 Community Regular

RPR33

Posted
Posted

I think it would, wouldn’t the wire measure the air and then calculate that by 2.5'' pipe

so if the pipe was 3'' the air would measure the same but there would be more air in the 3'' pipe then the 2.5'' pipe.??

I'm just guessing..

mad082 Grand Master

mad082

Posted
Posted

area of a 2.5" pipe = 31.6cm2

area of a 3" pipe = 45.5cm2

the bigger pipe will flow more air, but since the sensor only reads what goes though the little hole it sits in, then calculates how much air that is for the designated size of the pipe, when you put it into a bigger pipe it throws the calculations out and you end up with leaner mixtures.

WazR32GTSt Grand Master

WazR32GTSt

Posted
Posted

as has been said, the AFM wire will indeed sense less amount of air, but all this will do will make the car run leaner as it will add less fuel. without tuning it would be useless. and given you'd have to tune, it makes sense to go z32 if you are going the whole hogg

btw.. nissan AFMs use a hot wire with variable resistances, right?

mad082 Grand Master

mad082

Posted
Posted

but since you generally have to run some form of either piggyback or full ecu to run a z32, i don't think that leaning out would be an issue since you have to get it tuned for the afm either way.

personally i'd just get an ecu that uses a map sensor.

r32gt_rb20 Rookie

r32gt_rb20

Posted
Posted (edited)

just know about this a while ago....

found a webpage that did this...and in the same time...upgraded his injectors...

so i think there wouldnt be any problem if u cut off the AFM and fit it in a bigger pipe and in the same time fit in a bigger injectors....and tune it back to optimal settings....

i just dont see a problem with this MOD...

plus...u can save some cash....for budget drifters....

Edited by r32gt_rb20
GeeTR Grand Master

GeeTR

Posted
Posted

Bah, pack of gurls! =)

There’s a risk, but in reality if you seal the sensor to the pipe well ( careful not to use any noxious adhesives that will eat the PCB) and tune it properly, ( piggy back, FC) it would be well impressive to get it working.

Perfect for the budget conscious.

That said, for $300 there’s no way i would risk my motor :D

M

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