Maxed AFMs in GTR - Alternatives to Z32s?

[Mik]

The AFMs in my GTR are maxed out. Is there any alternative to running Z32 AFMs? The reason I ask is that I would like to retain the stock air box. I don't want to fit pod filters. I think I have seen NISMO AFMs. I'm assuming these will bolt straight in and even plug straight in? I don't know where to buy them from though.

[R32-GTS]

RB20det AFM's plug straight in.

[GTR4ever]

RB20det AFM's plug straight in.

is that for sure?? could someone elaborate please??

size / max out / fitment compared to RB26 AFMs ??

[Sydneykid]

RB26 AFM's are 65mm ID, RB20/25/Z32 AFM's are 80 mm ID. What R32-GTS is saying is, the electrical connectors are the same on RB20 and RB26 AFM's so "they"plug straight in". The standard rubber hoses from the turbos will stretch to fit the larger OD. But the AFM's won't bolt up to the standard air box. If you have pods then just upgrade the bases to RB20/25 ones.

Hope that helps

[GTR4ever]

RB26 AFM's are 65mm ID, RB20/25/Z32 AFM's are 80 mm ID.  What R32-GTS is saying is, the electrical connectors are the same on RB20 and RB26 AFM's so "they"plug straight in".   The standard rubber hoses from the turbos will stretch to fit the larger OD.   But the AFM's won't bolt up to the standard air box.  If you have pods then just upgrade the bases to RB20/25 ones.

Hope that helps

if so, then how come every one is after the Z32 FMs?? since RB20 AFMs are fit??

arent they cheaper too??

dont mean to hijack, but would a GTR33 benfit from such an apgrade if it was stock with mearly some basic bolt-ons??

[Sydneykid]

if so, then how come every one is after the Z32 FMs??  since RB20 AFMs are fit??

arent they cheaper too??

dont mean to hijack, but would a GTR33 benfit from such an apgrade if it was stock with mearly some basic bolt-ons??

Replacing an RB20/25DET AFM with a Z32 AFM is a worthwhile upgrade if the RB20/25DET AFM is reaching its max voltage and causing tuning problems as a result. This seems to have flowed over to GTR's even though it isn't really necessary in most cases. After all why worry about spending a couple of hundred dollears extra on Z32 AFMS compared to RB20/25 AFM's? Many people spend tens of thousands on their GTR upgrades, so what's a couple hundy here or there?

Plus why take a risk, they might make enough power to max out the RB20/25 AFM's. Just buy the biggest and baddest and not worry about it. Perosnally I prefer to buy the right size for the power target, this table may help;

Rule of thumb for Air Flow meters RWKW & Engine BHP

------ ---- OD ---- RWKW ---- RWKW ---- BHP ------ BHP

No of AFM's ---- ------- 1 -------- 2 -------- 1 -------- 2

RB26 ------ 65 ------ 149 ------ 299 ------ 271 ------ 474

RB20/25 --- 80 ------ 226 ------ 453 ------ 376 ------ 683

Z32 ------- 80 ------ 255 ------ 511 ------ 415 ------ 763

Q45 ------- 90 ------ 302 ------ 605 ------ 479 ------ 890

Please note that this is only an indication, every engine is different and tuning makes a big difference. For example, I have seen a GTR equiped with twin Q45 AFM's make 1100 bhp.

RB20/25 and Z32 AFM's are all 80 mm OD, that's outside diameter, not ID that's inside diameter. There is no real difference between an RB20 and an RB25 AFM. On the other hand the Z32 AFM is calibrated differently, so at the airflow the RB20/25 AFM shows max voltage, ~5 volts the Z32 afm is only showing ~4 volts. This means when the airlfow gets higher the Z32 can still show voltage increases to the ECU.

Q45 (Infinity) AFM's are 90 mm (OD), so they have the same calibration advantage but they are also larger in diameter for less restriction.

Hope that helps:cheers:

[Mik]

Well the RB20/25 ones would be easier to fit, so I don't have to butcher the looms.

But, I really didn't want to fit pod filters. I guess there is no other way.

Does the GTR power FC have the RB20 AFMs in it's table of AFMs?

Are there any 65mm AFMs with a higher load resolution?

[pnblight]

i fitted rb20 afm to my gtr r33 and the pfc has a selection for rb25 afm which worked a treat for me a i believe there is next to no difference and i am running over 500 hp at the wheels so unless you want to go over about 550hp at the wheels the rb20/25 will be fine

and i have heard of guys doing small mods to air bow to make them fit both rb20/25 and z32

[Mik]

i fitted rb20 afm to my gtr r33 and the pfc has a selection for rb25 afm which worked a treat for me a i believe there is next to no difference and i am running over 500 hp at the wheels so unless you want to go over about 550hp at the wheels the rb20/25 will be fine

and i have heard of guys doing small mods to air bow to make them fit both rb20/25 and z32

Do you run the air box or pod filters?

What about the RB30E air flow meters (VL and R31). Are they the same as a Z32?

[Sydneykid]

1.Well the RB20/25 ones would be easier to fit, so I don't have to butcher the looms.

2. But, I really didn't want to fit pod filters. I guess there is no other way.

3. Does the GTR power FC have the RB20 AFMs in it's table of AFMs?

4. Are there any 65mm AFMs with a higher load resolution?

1. You don't have to "butcher the looms" I splice in the larger AFM wiring harness in parrallel tothe standard plugs. This means you can swap back to the std AFM easily.

2. ARC (and probably others) make an airbox that fits the 80mm AFMs. You can modify the standard airbox, basically you just cut out the 65mm flanges and replace them with aluminium sheet for 80 mm. Sounds hard/shonky but looks good when finished. I have some pictures somewhere of one modified, I will try and find them.

3. Yes

4. Yes, there a few Jpanaese tuning shops that used to make them, swap the Z32 hot wire in to the GTR AFM body. But they aren't very common, most people went for the cheaper and more effective 80mm option.

Hope that helps

[go_nuts]

Didn't Merli or meshmesh butched up their stock airbox to fit those Z32 AFMs?

[BNR32]

ARC make a really nice aluminum or carbon fibre replacement box for 80mm Z32 afm. I just did the upgrade and without any other modifications except for Z32 AFM and power FC tune i saw an increase of 60 RWHP.

I bought my Z32 AFM brand new in boxes from www.nengun.com for $449 per afm, that is unbeatable price for brand spanking new AFM. He threw in the tomei adaptors so there was no butchering at all. Apexi PowerFc has a function to run the Z32 afm, so i dont know why you would consider doing anything else, all of the hard research has been done for you. Z32 work well and consistently and at the nengun price they are cheaper than most second hand half shit afm's.

TG

[PHaT MR30]

easy, Power FC, delete AFM's!!! problem solvered!

[GTR-Ben]

PowerFC uses AFM's, D-Jetro dosn't.

[ricknismo]

how hard is it to set up map sensors yourself?

[RPMGTR]

Use Nismo GTR afm's........dimensionally the same as a std GTR afm (bolt and plug straight in), and scale like a Z32........too easy

[Roy]

So the smaller throat diam of the GTR AFMs makes no difference.

Another thing a friend did, that i also see on Jap cars is remove the hot wire sensor from wahtever AFM you are using and simply drill a hole in your inlet pipes to suit. Some good resin to seal it, onto the pipe, and away you go.

If i go twin with RB26 head thats all i was going to do with the Z32 or Q45 AFM with the std RB20 Pfc. But i was going to try and put the full AFM in the pipe from the intercooler to Inlet plenum, figured the AFM may even read more accurate as it is sensing the cooler air post intercooler...would have to extend the wiring though...ppls thoughts?

[lwells]

ARC make a really nice aluminum or carbon fibre replacement box for 80mm Z32 afm. I just did the upgrade and without any other modifications except for Z32 AFM and power FC tune i saw an increase of 60 RWHP.

Slightly OT, but does the ARC airbox run the same (sized) filters as the standard airbox, or does it have its own special ARC items?

LW.

[Emre]

So the smaller throat diam of the GTR AFMs makes no difference.

A 65mm orifice can flow "xxx" litres per minute, under 20 psi supply pressure.

2 x 65mm orifices will flow similar to a single 90mm orifice, which incidentally is the inlet and outlet diameter of the intercooler. (from memory the inlet of the plenum as well)

An 80mm orifice will flow "xxx" lt/min @ less supply pressure, so it could be argued that they are less of a restriction. However, what is the benefit of fitting larger AFMs and leaving everything else stock sized ? It would be like expecting HP gain from a 4 inch hotdog on a 3 inch exhaust.

lwells,

AFAIK, ARC box for a GTR has two filters. One is similarly sized to standart filter, the other is considerably larger.

The biggest downfall of them is that, they are not sealed on top.

This is judging by the photos on their website.

[ricknismo]

so where can you get nismo afm's cheap. I have seen them for over $400 each which is way more than the cost difference between the afm power fc and the non afm power fc