Afm In Intercooler Piping

[Kaido_RR]

Hey,

Just upgraded my turbo again (low mount -> highmount), the turbo has a 4inch outlet, now my old turbo also did and i ended up just using a 4inch to 3inch reducer and using a 3 inch pipe.

I want to run a 4inch pipe this time however the AFM is the limiting factor as it is only 3inchs, so after doing some looking/research looks like the go is to move the afm to the intercooler piping (throttle side).now i am running a 26 plenum so there will be no issue placing afm there. However i just would like to hear people opinions on moving the afm to the i/c piping?

Please note this has NOTHING to do with sound etc... i run twin stock gtr bov.

thanks

[sriver killer]

Hey,

Just upgraded my turbo again (low mount -> highmount), the turbo has a 4inch outlet, now my old turbo also did and i ended up just using a 4inch to 3inch reducer and using a 3 inch pipe.

I want to run a 4inch pipe this time however the AFM is the limiting factor as it is only 3inchs, so after doing some looking/research looks like the go is to move the afm to the intercooler piping (throttle side).now i am running a 26 plenum so there will be no issue placing afm there. However i just would like to hear people opinions on moving the afm to the i/c piping?

Please note this has NOTHING to do with sound etc... i run twin stock gtr bov.

thanks

i played around with this on my r33.

ran alrite, but under load used to stutter real hard. i guess the afm's don;t really like it.

i just put the afm back where it was, cause thats where its meant to be

[STATUS]

what turbo?

[Kaido_RR]

what turbo?

HKS 3037S on RB25

[XRATED]

Why not try a Q45 AFM?

It's larger than a Z32/RB25 etc.

Run a 4" intake all the way from AFM back.

[STATUS]

it wont be a restriction in front of the 3037 but if you really dont want it there you can fit it in the cold side of the cooler piping. It will need rescaling in the AFM volts table.

[msports180]

The other thing to remember when going the AFM in the intercooler piping is the PCV. U cant run a return from ur catch can into the intercooler piping or your risk contaminating the AFM.

[toy515]

hmm i never thought of doing this, how would you do it on a 26 is it possible?

[STATUS]

hmm i never thought of doing this, how would you do it on a 26 is it possible?

same way but you need to join the two afm signals together (not ideal) from the one AFM but it works.

[toy515]

what do you mean by joining them together?

[R31Nismoid]

splice the wires... you can't just use two AFM's inline with each other.

You just use one, splice the wires and use the feed to the ECU that way.

Hardly ideal, but does work.

[toy515]

splice the wires... you can't just use two AFM's inline with each other.

You just use one, splice the wires and use the feed to the ECU that way.

Hardly ideal, but does work.

so i only use one afm and join the wires into one plug? will this hold the same power?

[R31Nismoid]

You are splitting the signal, so effectively it's the same as having two of the same AFM.

However this is all after turbo remember, not before.

The AFM's are designed to measure the air going into EACH turbo, not the end result. So i could imagine there would be differences - so not ideal as stated.

[eXquiSit]

any updates on this?

it seems that q45 afm has such a low signal on idle that it is hard to get a good idle?

is this correct?

[paulr33]

re: AFM's and signal

the ECU actually takes an average of both AFM signals and uses this for it's load axis calculation.

by having two AFM's you ensure the signal is a good split between both turbochargers

if you run one AFM (as some do) you can wire up the output Signal wire from the single AFM into AFM 1 and 2 inputs on the ECU

this effectively gives the same result as the ECU will just perform average anyway. the apexi SAFC lets you do the same thing.

that is, use two AFM's on a single AFM ECU or single AFM on twin AFM ECU. both should work.

the same can apply for djetro map sensor, but the known gotcha is manifold pressure is "finiky" on individual throttle body setups

i believe this is why the map sensors must be installed verbatim to apexi's documentation on the GTR for correct operation

re: Q45 AFM

hi

we have been trying to identify real Q45 AFMs vs bogus ones and we never found an answer

we think there is more than 1 style / batch of Q45 and some work really well aka 400rwkw and some work like ass sub 200rwkw

id be interested to see your part # and model #

but a real geniune Q45 as apexi intended it, should idle off the bat with their VH41 AFM selected off the ramp table

[eXquiSit]

interesting!

becuase i was researching on the net and every1 seems to say to go z32 and not to bother with the q45 because of poor idle!

idle would be important in a daily driver...maybe not so much in a 400kw race/drift/dyno car... something else to consider i suppose

how does the fake q45s fail to make power over 200kw?

[paulr33]

i see no reason why a geniune Q45 would have poor idle

i would suspect something is wrong, ie wrong AFM, damaged AFM, dirty etc

when we say fake Q45, as in, someone that think's it's a Q45, sold as a Q45 (on ebay etc)

but it *may* be just another nissan OEM looking AFM that has the same yellow label and size

[paulr33]

a Z32 is fine for upto around 350rwkw, i think ash did 360rwkw with one and it was fine

the Z32 is easier, because its cheaper, easier to find, works well every time, is 80mm - so direct swap, same bolt pattern etc

The Q45 is probably more annoying is it's less common, larger 90mm so you have to change pipework etc

and theres the gotcha in that you may get one that performs like ass, ie; possibly non-geniune Q45 or something that looks like a Q45 and it isn't

[paulr33]

i actually just remebed the original chart apexi has for power level vs AFMs

<Reference>

80m RB25 airflow meter can measure up to approx. 300ps (221kW)

80mm VG30 airflow meter can measure up to approx. 500ps (368kW)

90mm VH41 airflow meter can measure up to approx. 400ps (294kW)

so you can see they rate the Z32 higher

[paulr33]

after some thought i see no reason to use or bother with a Q45

given the Z32 rates higher, is smaller in size and easier to source why bother with the Q45

there are a number of different part #s for the Q45 and its not supported on all PFC's

so ill be updating my PFC FAQ to say no to Q45 as it's a pointless mod and only add's confusion and poor results

the z32 is higher rated and works everytime, direct swap from 80mm and easier to source