Power Fc

[croat]

im considering swapping from my current power FC to another computer as i dont want to use an afm. I have a 4" mouth turbo which will look stupid if it narrows into a 2.5" Z32 air flow meter. what is another good computer to use? can power FC be used without an afm? what is the power FC DE-Jetro?

Thanks..

[paulr33]

the FAQ covers all these questions and many more, but in summary

djetro = map sensor driven (ditch afms)

for most applications the ljetro (airflow meter) version is more suitable and easier to tune. i would recommend single Q45 in your case which is 90MM opening diameter which is one of the bigger airflow meters, natively supported by the powerFC also.

i cant see you getting any other out of the box good support from other ECU's im afraid

[R31Nismoid]

You wanna change ECU's because it "looks" not nice?

As paul said above, d-jetro will do it

otherwise the wolf is a plugin, or near enough to it.

everything else is a rewire far as i know

[croat]

where can i get the d-jetro from? can this be tuned everywhere as the AFM version? is it a better version of the power FC (better mapping?).

i personally thing the 4" pipe into the 2.5" pipe looks stupid but i could prob deal with the 3" Q45 deal..

thanks..

[2BNVS]

going by personal experience from puttin a power fc on, having it tuned as good as it got and then putting my AUTRONIC SM4 on it, was ridiculously different, u want an awesome ecu get an autronic sm4, its mapping, and every other part of it, is phenominal and personally well worth the money...

i like it with no afm hehe

ben...

[StockyMcStock]

dude, put your AFM in the cooler pipe. fixed.

[paulr33]

agian, if you read the FAQ you would have learnt how AFM and MAP is different in terms of mapping. in summary;

airflow meter is better and more tunable

map sensor gives you less load points that are usable

as you can see lots of people agree with keeping the AFM, so its likely there is a good reason for it

[croat]

yeah read your tutorial paulr33, very nice!

Stockmcstock what do you mean by "dude, put your AFM in the cooler pipe. fixed."? how do i do this??

[paulr33]

you relocate the AFM in the pipework after the intercooler but before the throttle body. like where the rb25 pipe work joins up with silicon joiner, near the NISSAN 2500, relocate it to there in between the pipework and you can have the turbo opened mouted with whatever air intake you see fit

[rb26s13]

q45 is 3.5inch z32 is 3inch and it doesnt look that stupid wat turbo are you using? 4inch belmouth i'd assume GT30? z32 should be more than enough for that setup regardless of wat it looks like

[rob82]

agian, if you read the FAQ you would have learnt how AFM and MAP is different in terms of mapping. in summary;

airflow meter is better and more tunable

map sensor gives you less load points that are usable

as you can see lots of people agree with keeping the AFM, so its likely there is a good reason for it

Mate its got nothing to do with the amount of load points!! I've got to agree though and if you do go to a MAP based system go the SM4 without doubt the best MAP based ECU and in my experiences I would stay well away from wolf.

[Gav]

airflow meter is better and more tunable

Why do you think so? I've seen a number of GT-Rs gain power when converting to D-Jetro from std PFC.

map sensor gives you less load points that are usable

Again - why? The D-Jetro has 20x20 load points that are configurable.

[paulr33]

the problem doesnt stem from max power or how it performs on the dyno. the problem stems from how a map sensor system guesses the amount of airflow in the manifold. as its a guess based system it will never be as accurate as an airflow meter measuring it directly.

once you reach max boost as designed by your gate, controller, solenoid or what not the map runs across a horizontal axis, so you don't scale down as more and more air coming into the system increase. this is due to the way map guesses airflow based on pressure.

volume and pressure are two different thing

the map setup says

if i have 0.50kgcm2 pressure and my guestimation calcuation is:

pressure x magic-number (lets pretend its 10800) = amount of air we get;

0.50 x 10800 = 5400

so our current airflow equals 5400 units. now the AFM version would say lets pretend 5400 airflow units also. now as boost pressure increase more and more air is coming into the system so the AFM signal goes up.

so lets say we now have reached target boost (say 1.3bar)

1.3 x 10800 = 14040

and our AFM says there is 14000 units of air present

now we are at 4500rpm so theres lots more RPM to go

AFM = 14000 units @ 4500rpm

MAP = 14040 units @ 4500rpm

now lets pretend we have had full throttle nailed for some time and are at 6500rpm

using our same equations (we are still at target boost)

MAP

1.3 x 10800 = 14040

AFM says 18000 units of air present

the AFM has clearly shown more air has come into the system ,as RPM increase more air comes in, despite the same fixed pressure.

So what happens in turn is the djetro version or map sensor version shoots across the RPM axis as load never changes, as the MAP guesses air present based on pressure, which never changes.

The AFM version keeps scaling across both the RPM and Load axis as more air slowly is coming in and RPM is being increased. so it scrolls diagnoally if that makes sense.

[MerlinTheHapyPig]

Mate its got nothing to do with the amount of load points!! I've got to agree though and if you do go to a MAP based system go the SM4 without doubt the best MAP based ECU and in my experiences I would stay well away from wolf.

why avoid the wolf? they are quite similar in specs to the SM4

[paulr33]

yes the map points for djetro are still 20x20 and you can confgure them via datalogit but the same base problem is still there. once you reach the same base pressure in the manifold, ie: target boost the load axis never increases

and this is where you loose load points, as from that point onwards you just run in 1 dimensional tune. whereas the airflow meter still has 2 dimensional as there is always more airflow

assuming the airflow isnt maxing out and flatlining, but thats another problem in itself

[paulr33]

Why do you think so? I've seen a number of GT-Rs gain power when converting to D-Jetro from std PFC.

Again - why? The D-Jetro has 20x20 load points that are configurable.

also curious how an ljetro vs djetro setup magically makes it gain more power?

was it maxing out the airflow meters in use? i dont see you would make more power on a map sensor setup, they both achieve the same goal, albeit the map sensor has a crapper version of it

[MerlinTheHapyPig]

the AFM has clearly shown more air has come into the system ,as RPM increase more air comes in, despite the same fixed pressure.

So what happens in turn is the djetro version or map sensor version shoots across the RPM axis as load never changes, as the MAP guesses air present based on pressure, which never changes.

The AFM version keeps scaling across both the RPM and Load axis as more air slowly is coming in and RPM is being increased. so it scrolls diagnoally if that makes sense.

Actually, i have found, if you have a look at actual data it doesn't really make much difference.

The load calculation that the ECU makes is also influenced by the engine RPM (if you look at actual calculation for TP), so the calculated "LOAD" figure will still increase even when you are at full boost. (it is then referenced on a graph of TP vs RPM, so RPM is really used twice here by the looks of things!)

Personally, i think AFM's are fine, but they do pose a problem when they run out of resolution, or the AFM poses a restriction on the intake. MAP sensors are handy because their resolution is only limited by the amount of boost it can read (typically 50psi or some insane value)

I think it would be rare for a skyline motor to exceed the voltage limit of a Q45 afm, but i'm sure it's been done before. Maybe look at what some of the top GTRs in japan use for engine management and make a decision based on what the experts use.

[MerlinTheHapyPig]

once you reach the same base pressure in the manifold, ie: target boost the load axis never increases

"load" isn't just the boost, it also takes into account RPM and a few other factors (see my previous post)

-- for stock ecu, i don't know if djetro powerfc's use a different formula

[croat]

you relocate the AFM in the pipework after the intercooler but before the throttle body. like where the rb25 pipe work joins up with silicon joiner, near the NISSAN 2500, relocate it to there in between the pipework and you can have the turbo opened mouted with whatever air intake you see fit

i dont understand? are you saying you put the afm on intake side? i have a trust plenum so the afm should sit after then plenum? how would that work?

rb26s13 i am using a gt3540.

[paulr33]

Actually, i have found, if you have a look at actual data it doesn't really make much difference.

The load calculation that the ECU makes is also influenced by the engine RPM (if you look at actual calculation for TP), so the calculated "LOAD" figure will still increase even when you are at full boost. (it is then referenced on a graph of TP vs RPM, so RPM is really used twice here by the looks of things!)

Personally, i think AFM's are fine, but they do pose a problem when they run out of resolution, or the AFM poses a restriction on the intake. MAP sensors are handy because their resolution is only limited by the amount of boost it can read (typically 50psi or some insane value)

I think it would be rare for a skyline motor to exceed the voltage limit of a Q45 afm, but i'm sure it's been done before. Maybe look at what some of the top GTRs in japan use for engine management and make a decision based on what the experts use.

i have read down this path before and end up at the same result, when it was discussed some time ago and gary brought up the refence to HPI talking about ljetro vs djetro. the TPS when on max load would be fixed 3.98volts as you have the throttle nailed, so its still a 1 dimensional increase.

load is purely AFM or MAP

and lets pretend it was TPS as i just said its fixed when on max load so that doesnt help either.

sure if a given airflow meter is a restriction (given most people use 2.5" intercooler piping so it cant be that bad) and that turbo's have restrictions AFTER The AFM and NEVER before. then move to more than 1 airflow meter or get bigger ones that can measure more -> twin q45's should be big enough

if you think the AFM mouth is a restriction the move it to after the turbo compressor inlet

althought the restriction is after the compressor, not before