Larger Maf

[Rezlo]

Z32 and Q45 dont cut it, running a PFC in my RB25DET S1

Need larger, anyone tried cutting the sensor out the Z32 or Q45 and installing it into a larger diameter pipe? thinking of cutting out the sensor bar and installing it into my 100mm intake pipe as well as putting a smaller 40mm ID lexan tube round the sensor about 40mm long to stop air swirl or cross flow effecting it.

Just wondering if anyones tired anything like this? thought of changing to a GTR ecu but ive just got poncams for the VVT, dont want to kill that now.

Edited December 27, 2007 by Rezlo

[Cjmartz2k]

You can put the AFM in the intercooler pipe. This compresses the map so you can read a bit higher, but it's a little harder to tune and you have to retune for EVERY new mod. You can always use a Ford AFM from a newer lightening.

[mjfawke]

Z32 and Q45 dont cut it, running a PFC in my RB25DET S1

Why? If a Q45 AFM is too small, why are you running a PFC at this stage of tune?

[Rezlo]

Why? If a Q45 AFM is too small, why are you running a PFC at this stage of tune?

I use my car to demonstrate to a lot of customers the ease of the PFC, I thought of going with a GTR PFC but ive got a set of poncams which are obviously design for the VVT to be active, which I would like to retain.

Im not a fan of blow threw, Will look at the new lighting maf,

[Rezlo]

Humm, Are you guys that use Q45's using the newer year Q45 (pink sticker 31U00 E60 ) or older Q45 (yellow sticker 61U00 / P60) MAF's? All the ones I have here are the slightly older yellow sticker ones... which seem to be only hold slightly more than the Z32's

Edited December 28, 2007 by Rezlo

[STATUS]

how much power are you making? mid 400rwkw (600whp) is possible with the above AFM's

[Rezlo]

Im making enough that the Z32 maxed at 1.4bar and the Q45 maxed at 1.5bar, I used 3 different Z32's and 4 different Q45's all 7 maxed within .1bar of each other. I have double and tripple checked, there are no leaks what so ever anywhere and ive changed my intake setup 3-4 times over the last 2 years also with no change in being able to run more boost before it max's.

If it wasnt for the Poncams/vvt i would rip it out and use a D-jet R33 PFC, I have had similar results using Z32's and Q45's on all the SR20's I have done as well, all come 320-350wkw they are right up in voltage, using all different set up's and hosts of different intake lenghts, air filters ectr, how you guys get so many WKW out of them/what im doing wrong is beyond me, but its repeatable threw all the vehicles I have done over the last 7-8 years...

[paulr33]

when is the afm maxing out? if its up in the top rev range then its no different to map sensor style setup

with a map sensor style setup once you reach target boost load never increases so you run across the horizontal axis on the map

the same thing will happen when the afm maxes out, it will hit its ceiling limit and wont increase - so youll run across the horizontal axis on the map

in both cases when load stops increased more air is coming into the engine so you are no better or worse off

the only time i wouldnt think this would be a good idea was if you were maxing the afm at say 3000rpm

[Adriano]

Sorry paul i would have to disagree, when a map sensor voltage goes flat, it hasn't run out of resolution, if the boost goes higher, the voltage wilol change, if the maf is out of resolution, and the boost goes up, it will just lean out.

[RB30-POWER]

go gtr ecu with twin afms.

just get two $30 chiptorque shiftlights, they are small, throw away the light but use the output to drive a relay to turn the vct solenoid on at xxxx rpm then use the second one to turn on a second relay (normally closed here) to open circuit the first relay and the vct solenoid will turn off.

otherwise im sure jaycar do a freqency switch, unsure if it has two set points but, thats why i suggested the above or similar.

vct is the easiest part to solve really.

[paulr33]

correct if boost increases, so will map sensor voltage but if the car is setup for 22 psi once the map sensor see's 22psi it will be lets say 3.8v

this is then used to give the ecu its LOAD value and place it on the load axis - as the boost controller is set to control boost to 22psi - boost won't change until gearchange - therefor the map sensor value wouldnt change

when the afm maxes out say at 5000rpm at 22psi boost will still be 22psi but more air will be coming into the system

the afm will ceiling at 5.0v and show no more load - so the same result, LOAD on the ECU level wont increase and it will run across the last axis used

so in either way you have to just juggle the afr's and ign timing on the last row it runs across and you loose some map points

[paulr33]

go gtr ecu with twin afms.

just get two $30 chiptorque shiftlights, they are small, throw away the light but use the output to drive a relay to turn the vct solenoid on at xxxx rpm then use the second one to turn on a second relay (normally closed here) to open circuit the first relay and the vct solenoid will turn off.

otherwise im sure jaycar do a freqency switch, unsure if it has two set points but, thats why i suggested the above or similar.

vct is the easiest part to solve really.

haha thats a great idea

good thinkin 99

[STATUS]

correct if boost increases, so will map sensor voltage but if the car is setup for 22 psi once the map sensor see's 22psi it will be lets say 3.8v

this is then used to give the ecu its LOAD value and place it on the load axis - as the boost controller is set to control boost to 22psi - boost won't change until gearchange - therefor the map sensor value wouldnt change

when the afm maxes out say at 5000rpm at 22psi boost will still be 22psi but more air will be coming into the system

the afm will ceiling at 5.0v and show no more load - so the same result, LOAD on the ECU level wont increase and it will run across the last axis used

so in either way you have to just juggle the afr's and ign timing on the last row it runs across and you loose some map points

yeah but you have to comprimise i did my first 180 that way, HKS 3037 with std s13 afm.... the flatline needs to be power robbing rich for everything but full boost full load. It works but its messy and far from ideal.

[paulr33]

sure its a big comprimise but if its at 6000pm then its not that bad

how do you work around the same issue with a map snsor style setup

[STATUS]

Luckily with PFC we can adjust the voltage offset tables so you can actually run any AFM or MAP you like.

[paulr33]

yeah i understand you can dial in any map snsor with offset and pim scale etc

but if you have the stock apexi map sensor and you run say 15psi it could be say 4.2v

if you run say a 3bar GM map sensor and you run say 15psi it could be say 2.6v

once 15psi is in the manifild i dont see how pim1 voltage will increase any more

[RB30-POWER]

the problem with running it maxed out is you have to compromise run it rich for the max boost you want to run, so any less boost that is not down on a lower load point is filthy rich.

the second bigger problem is timing, because you have to retard for more boost, you have to do the same thing, set a low enough figure on the last load cells for the highest boost you want to run, but have boost below that amount and it will be to retarded until it drops low enough to access a lower load point.

i have been up this alley recently with a different vehicle and its the shittest setup ever and you risk your engine.

the only other way is to setup an air flow meter bypass, but that is still dodgy in my books, easier if you had a twin throttle bodied engine but.

this is the biggest problem with air flow meters, once you make serious power it can be a pain in the neck and easier to have gone a speed density system to begin with.

the only bigger maf is know of that will work is the ford lightning 90mm air flow meter, old mate in the us is using one and its only at 4.7V at 490rwhp, so its a real bad boy!!!

[Rezlo]

Yes this is complex, but honestly I cant see why the following is such a bad idea:

Cut the sensor bar out of a Z32 or Q45 (ill use a Q45 because I have loads of them laying around) and make a mounting flange, and mount it into the 100mm intake, the effective area of a 80mm ID Q45 is 5024mm2 going to 100mm would make it 7850mm2, also what would be a pretty nifty idea would be to use a short 40mm length of 40mm ID lexan thin wall tube and actualy mount it around the sensor bar so that the air flow threw the sensor is straight and undisturbed. this will give you a MAF capable of a lot more CFM before maxing, and with the PFC one could just re-scale it as needed.

Can anyone tell me why the above wouldnt work as a cheap and easy (well easy for me) method to solve maxing Z32 or Q45's

? another nice thing is it will have near no restriction.

[zebra]

Yeah.

But. The AFM still reads air going past it. RB25 AFMs are 80mm too and mine is maxxed with a std Turbo.

The Gain with Z32 or Q45 is that they are designed for bigger motors and are calibrated as such.

a 4.5L V8 will suck more air than a 2.5L 6 so its calibrated that way.

So as far as I can see (and correct me if im wrong) You could put a Q45 AFM in 200mm Pipe and it would still read the same.

[Rezlo]

Yeah.

But. The AFM still reads air going past it. RB25 AFMs are 80mm too and mine is maxxed with a std Turbo.

The Gain with Z32 or Q45 is that they are designed for bigger motors and are calibrated as such.

a 4.5L V8 will suck more air than a 2.5L 6 so its calibrated that way.

So as far as I can see (and correct me if im wrong) You could put a Q45 AFM in 200mm Pipe and it would still read the same.

No, the air flow speed over the sensor would be slower in 100mm than 80mm, with hotwire the reduced speed would = a reduced temprature on the heated sensor = lower voltage.