That would need to be done on a proper flow bench. I've never heard anyone here say they had access to one, so I wouldn't hold your breath waiting.

 

why does he start these pointless threads? does he have nothing better to do with his time than think of ways to post another thread that we've all seen before? until you come up with something worthwhile i'll continue making smart-*** replies. lol.

 

So tell me, what does this have to do with airflow potential between the two different designs?


-Ted

 

Um, did you compensate for the ***** in the center?
I don't think you can just measure the I.D. and totally ignore the fact that the airflow has to flow around the obstruction in the center.


-Ted

 

Ted, I'm on your side. I think the S5 is more restrictive too

My point is that it wouldn't matter if there's nothing on the inside, the inlet is still a lot smaller. So it's hard to see how it could flow better, which is the common misconception.

 

I do have a Super AFC on my car and we tuned it for ~13 A/F. (The car is an NA) Swapping the AFMs made no difference in our tuning and no changes needed to be made to the AFC.

The A/F ratios where very similar between runs. However I will admit that the resolution of the A/F ratio on the graphs is not detailed enough to show an exact point for point comparison. IE: Differences of +/- .2 are not detectable on the graph.

 

I guess it has nothing to do with airflow potential. But it does show that S5 had an advantage over the S4 when all other variables were held constant.

 

i'd think that in non-wot conditions the flow from the s5 afm would be smoother than the s4, but only due to a circular vs. square design. i'm not implying that this would make a real world difference though.

 

No offense, but I fail to see the point in measuring the airflow meters in the first place. A good standalone EMS is only $1,000-1,500, which allows for very little restriction in speed-density mode (MAP and IAT sensors), and absolutely no restriction in alpha-n mode (TPS). I realize that everybody is looking for a "cheap" way to get better performance, or some simple new and wonderous idea that nobody else has ever thought of, but in this case there is really no point unless one is just curious and has a lot of money and time to spend on something that has no value except as a learning experience.

 

I am not doing this so I can find the best AFM for my car. I am doing this because I thought of it and want to know the answer. I am purchasing a Microtech as soon as the new version is released so that isn't a concern for me anymore but I do want to shut people up that say the they KNOW which flows better and they don't show anything to back it up. How other people use this data I really don't care but I am putting it up here for everyone to see it and there to be a FACT based result not just "oh I think the S5 flows better" or the same with the S4.


Santiago


PS- No offense taken.

 

seems like a lot of work for 1-2hp

 

Which is why I'm going to spend less than $500 reprogramming the stock ECU to accept a MAF sensor.

....but there is a big difference between $30 for a used AFM and $1000 for an EMS. If we all had that much money lying around, we'd probably have FD's.

 

1) It will not work correctly because a MAF has a pressure signal and the AFM has a volume signal (corrected for temperature by the internal temp sensor).
2) Even if it did work, you would still be stuck with the slow stock ECU, which is the main problem with the stock system, not the "restriction" of the AFM.

Exactly my point. It is much better to spend $1,000 on something that actually has a benefit rather than throwing away $30 on a used piece of junk.

1) I do not own an FD.
2) One of the reasons that I do have money for a standalone EMS is that I do not waste $500 trying to get an old piece of junk ECU to work with a MAF sensor, nor do I waste my time or money trying to figure out which pathetic AFM is "better" than the other when I know darn well that a standalone EMS is better than both.

 

Uh I am not wasting any money as it isn't costing me anything. :-p I already have the parts to do it with. And I know that a stand alone is better.

 

LOL!

I know the signals are different that's why I'm going to reprogram the frickin ECU!.

Both sensors give an A/D convertor a 0-5V signal based on airflow. Changing the software allows you to change how the ECU responds to changes in this airflow.

And the comments about the "slow" stock ECU are just silly. If it's fast enough to read the signals and control the actuators, then it just is, period. It's not as if I'm trying to make it do any more thinking than it's already doing.

 

Oh, and a MAF sensor measures Mass Air Flow, a pressure-based system would use a MAP sensor.

Probably just a typo on your part though, as you knew the temp is combined with the flow to get mass flow (and therefore the proper amount of fuel to inject).

 

LOL, not a typo, just a major screw-up on my part due to not fully reading the post. I was on the phone while responding, so that was the MAP/MAF mixup. Sorry about that.

Anyway, the MAF isn't worth doing, either, lol. In the time it would take you to reprogram the stock ECU to work with the MAF, you could have worked at Burger King long enough to afford a standalone EMS. Also, it is going to be a major engineering feat to get the stock ECU to heat the AFM wire (MAF has input/output, while AFM has only output), and idle is going to be a real pain to set up because the stock ECU is set up for the AFM air bleed that will not exist with the MAF. Additionally, the stock ECU maps will not work quite right, so you will need to reprogram them also, unless you are looking for MAF bragging rights more than you are looking for a well-tuned engine.

If you still insist on this project, note that the S5 ECU is twice as fast as the S4 ECU, so if you are going to reprogram one, the S5 is the way to go. No, the ECU speed is not silly. A fast, modern, ECU like the Wolf3DV4 Plus and the Haltech E11 run the engine much better at idle and during changing rpm conditions. I guess it is difficult for people to understand this unless they have tried it themselves. Also, the MAF has a huge problem with reversion waves screwing up the signal, so make sure you keep it well away from the TB, much like the stock AFM.

 

....but then I wouldn't learn anything, would I?

 

it's not a pointless thread, it's just a discussion and a much better one than "how much power from this ebay muffler." the power differences bewteen an S4 and S5 AFM are not relevant to what they can flow...each one likely has very slightly different mixtures hence a small gain from someones dyno test (I bet the S5 runs a tad leaner for mileage improvements, just a guess). as far as flow goes, it makes more sense that the S4 has the advantage since under load nothing is restricting the intake path. however, i'd bet the S5 is a more durable piece...

 

Hehehe, yes, but the problem is that you will learn that you should not have wasted your time with that project, and bought a standalone EMS instead. Then you can take my place as the cranky guy on the forum who tries to keep people from wasting their time and money on ghetto EMS projects.

Anyway, this link may help:
http://www.superstang.com/maf.htm

 

Not really, because there are variables that you can't hold constant during dyno runs. It's entirely possible to get a 3-4hp difference between two back to back dyno readings without changing anything.

A 1hp difference doesn't conclusively prove that one is better than the other, but it does prove it's not worth doing the swap.

 

one other thing to think about is that the s4 afm is fully adjustable, you have an adjustment for the spring tension, and you can move the flapper door vs the resistor and you can add a stop like the 1st gens have, if you need it

 

Plastic is more durable than aluminium?

 

Good link. I've already found that one and a few others. I spent some time researching the 88 Corvette vs. the 88 Mustang MAF sensors and decided to got with the Mustang's. More details are posted in my ECU thread.

AFAIK no one has attempted a MAF project like this before for the 2nd gen rx-7. There's a company selling new EPROMs with a couple minor changes, but it doesn't seem like anybody's tried this before.

This shouldn't end up being a ghetto mod anyways.
It would require 3 things:
-replace EPROMs
-connect MAF sensor
-possibly add a few jumper wires inside the ECU

Since my car is stock, the conversion tables I come up with should work fairly well for any stock RX-7.


As far as the topic of this thread, it is far from pointless. There are way too many people who make unsubstaniated claims about performance. It's always nice to see someone try and collect some real data.

 

I'm fairly new to this but my thaughts are that the s4 alloy afm was replaced by the plastic one in the s5 for less heat absorbsion from hot air in the engine bay maybe. Correct me if im wrong lol, i probably am but doesnt alloy withstand heat for abit longer than plastic but when hot it would become hotter than plastic and therefor make air intake temp higher? and maybe denso changed the afm type from flapper to cone because it worked better with the s5 ecu and fuel maps etc?

One more thing to remeber is that the s4 was mazdas first intercooled turbo 13b so it was somewhat of a base that they could improve on with each new model to come. It just seems strange that they would use a more "restrictive" afm on the s5 with the much improved engine/ecu setup etc? I just dont see mazda "downgrading" on such a vital part of the engine so all in all i personally see the s5 afm as being better than the s4.... please dont bite my head off if you disagree lol