Alternative MAFs?

manga_blue · Postby **manga_blue** » Wed Jul 14, 2010 9:04 pm

What other MAFs can go on an NA8?

The OEM MAF looks like a big choker. Its effective cross sectional area looks tiny compared to its diameter. Pic shows NA vs NB MAFs with NB on the left.

NA v NB MAF 2.jpg

The NB8A MAF design looks a lot better but the recently revived Cams discussion talks of measurement problems for OEM MAFs due to back pulses from larger cams. There's a mention of Suby or Focus ones being better alternatives but doesn't say which ones.

93_Clubman · Postby **93_Clubman** » Sat Jul 17, 2010 1:37 pm

MB, Prinju posted that when he was up at Winton one weekend someone advised him to use a Skyline MAF - can't find the post as it's pre late 2005 & didn't make it across in the Forum upgade of 3-4 years ago, however Prinju does later post that he's got a Skyline RB20 MAF which he's attempting to adapt:
viewtopic.php?f=29&t=16525
viewtopic.php?f=29&t=15568

Sheck also mentions the Nissan MAF:
viewtopic.php?f=29&t=25044
viewtopic.php?f=29&t=21217&start=15

manga_blue · Postby **manga_blue** » Sat Jul 17, 2010 7:24 pm

Thanks Paul, it's not easy to get this info, is it? Lots of guys have played around with NA6 AFMs but tinkering with a Mazda MAF seems pretty rare. That last post of Sheck's suggests a possibility of wandering down to a wreckers and trying Nissan ones for size.

FWIW I've been logging the stock MAF. The 2 lines on the plot are MAF voltage at WOT, top, and closed throttle, bottom.

NA8 MAF v RPM.jpg

As long as something reads vaguely like an MX5 MAF then I can tweak the load maps to make it work.

BadBong · Postby **BadBong** » Sat Jul 17, 2010 11:53 pm

Please excuse my ignorance but a MAF is.... :oops:

?

sliq · Postby **sliq** » Sun Jul 18, 2010 1:36 am

do a search badbong re air flow meter

Mr Morlock · Postby **Mr Morlock** » Sun Jul 18, 2010 12:18 pm

this is a device for measuring air flow and impacts on the function of the ecu to deliver the correct fuel to the engine. The theory of this is long way over my head. Wiki will give you info.

93_Clubman · Postby **93_Clubman** » Sun Jul 18, 2010 12:50 pm

Phil, info seems scarce, but I'd be surprised if it's not out there somewhere, may be just tightly held. I'd heard the NB8 MAF had a bigger cross-sectional area compared to NA8, but was also aware it's not PnP, given going from hotwire MAF to a standalone air temp sensor & MAF, as well as different electrical plugs. I did some looking around at the time of Prinju's post & found the following pics of Nissan MAFs if they're any help, but given the time since someone might have found a Suby or Focus better alternative:

skyline maf DSC00037.jpg

skyline maf DSC00039.jpg

skyline maf DSC00040.jpg

skyline maf hcr32 DSC00040.jpg

skyline maf hcr32 DSC00043.jpg

93_Clubman · Postby **93_Clubman** » Sun Jul 18, 2010 12:52 pm

nissan skyline r33 gtst afm 02_1_b.jpg

nissan skyline r33 gtst afm e3_1_b.jpg

manga_blue · Postby **manga_blue** » Sun Jul 18, 2010 6:58 pm

Thanks again, Paul, I appreciate the searching. Looking at Nissan options then I've found:
1 X SR20 AFM = 170Kw
1 X RB20/25 AFM = 370 bhp = 220 rwkw
1 X Z32 AFM = 420 bhp = 260 rwkw
2 X RB26 AFM's = 475 bhp = 300 rwkw
2 X Z32 AFM's = 700 bhp = 470 rwkw
1 X Q45 AFM = 480 bhp = 300 rwkw
2 X Q45 AFM's = 850 bhp = 550 rwkw
NB, these are all hotwire MAFs, not flappy things as we understand the term AFM

On that basis I reckon even a stock SR20 might well do for size, just need to undertsand the pinouts.

BTW, from measuring the NA8 and NB8 MAFs here at home I have calculated effective cross sectional areas of 1,174mm2 for the NA8 and 2,895mm2 for the NB8. This compares to 2,138mm2 for the throttle body itself. I have a strong suspicion that Mazda didn't have many options in the parts bin when they selected that tiny MAF for the NA8 and started to rectify the mistake with the NB8.

Fatty · Postby **Fatty** » Sun Jul 18, 2010 7:57 pm

phil i'm not trying to tell you how to suck eggs, i'm just thinking that you probably want to take a fairly cautious approach and make sure that try to find something that's output signal is fairly close to existing maf. i guess my main concern is that (according to my very basic understanding of how they work) maf's are a little bit more complex than a flap door afm, which just outputs the same voltage for a given airflow regardless of temperature, humindity, air density etc. i think a maf's output may vary with different temps and so forth, thus adding some more complications to deal with.

you probably already know more about this than i do but just thought it'd be worth mentioning... and maybe it's not as complex as i think it is.

it might be worthwhile trying to set up a test bench of sorts and compare the existing maf with any other candidates and read the outputs... somehow feeding air thru both at different speeds, temperatures etc. could be a fun project

i expect a hairdryer and a vacuum cleaner could be handy for this :lol:

93_Clubman · Postby **93_Clubman** » Sun Jul 18, 2010 9:19 pm

Phil, I remeber reading the flow figures, & as you probably know a normally aspirated NA8 doesn't need a lot more flow, indeed some say it doesn't need any more. So I think NB8 size would be about right for an NA NA8, possibly even for one that's been tweaked but, given your original post, if the NB8 MAF isn't optimal then going slightly larger wouldn't hurt if technically possible.

manga_blue · Postby **manga_blue** » Mon Jul 19, 2010 8:28 pm

Fatty wrote:it might be worthwhile trying to set up a test bench of sorts and compare the existing maf with any other candidates and read the outputs... somehow feeding air thru both at different speeds, temperatures etc. could be a fun project i expect a hairdryer and a vacuum cleaner could be handy for this

Well picked, Fatty. That was exactly my plan.

If worst comes to worst with the output curve then I can always use a Jaycar DFA to emulate the old curve. As I read further it looks like the harder bit may be dealing with heating/self-cleaning functions in some models.

The main problem with the NB8 MAF is that the one I've got is cactus. When I bought it I failed to ask one small but important question: "Does it work?"

93_Clubman · Postby **93_Clubman** » Mon Jul 19, 2010 9:43 pm

manga_blue wrote:The main problem with the NB8 MAF is that the one I've got is cactus. When I bought it I failed to ask one small but important question: "Does it work?"

Ah - was one on ebay for about $90 a week or so ago - think it's still there.

Matty · Postby **Matty** » Wed Jul 21, 2010 11:41 pm

Hi Phil, I've got a NB8A MAF here you can play with if you want.

Matty · Postby **Matty** » Wed Jul 21, 2010 11:44 pm

Fatty wrote:phil i'm not trying to tell you how to suck eggs, i'm just thinking that you probably want to take a fairly cautious approach and make sure that try to find something that's output signal is fairly close to existing maf. i guess my main concern is that (according to my very basic understanding of how they work) maf's are a little bit more complex than a flap door afm, which just outputs the same voltage for a given airflow regardless of temperature, humindity, air density etc. i think a maf's output may vary with different temps and so forth, thus adding some more complications to deal with.

you probably already know more about this than i do but just thought it'd be worth mentioning... and maybe it's not as complex as i think it is.

it might be worthwhile trying to set up a test bench of sorts and compare the existing maf with any other candidates and read the outputs... somehow feeding air thru both at different speeds, temperatures etc. could be a fun project i expect a hairdryer and a vacuum cleaner could be handy for this

Tweaking MAF output isn't particularly hard - plenty of articles on Autospeed about doing this - either digitally (interceptor) or passively (resistor bridge).