Want less intake restriction? - A 929 AFM works!
 

I thought I'd start a new thread on this.

It is plug & play, except that fuel goes 40% rich.
It takes something like an S-AFC to adjust for the flow difference.
I had to dial back all my set points by 40%.

Oh yea - it is bigger...

The inlets:
http://208.62.166.66:82/guest/pics/91TII/TID/AFM-in.jpg

The outlets:
http://208.62.166.66:82/guest/pics/9...ID/AFM-out.jpg

Installed:
http://208.62.166.66:82/guest/pics/91TII/TID/AFM.jpg

I got this one on e-bay for $31.
I think it's the same one the Cosmo used.

this is a cone-type AFM? Does that work on an s4?

Hmmm the pluger is also much bigger...

any dyno test or 0-60 tests before and after???

sweet, is it plug and play? noticable gain? what year 929 afm did you use? how much did it run you? -alex

The big plunger takes less force to move because if its larger area.

The venturi opens way wider as the plunger depresses, so the ID/OD difference is more.

The plunger has a longer stroke.

AND - THE BIGGIE - The ECU & the S-AFC can handle it.

I hope to play with the G-tech this weekend.

these can in fact work on the s4 correct?

The S4 plug is different, but you could rewire it.

I think someone said the S4 AFM actually flows better than the S5.

hmm...i would need then a S5 plug and the 929 afm. so i think ill wait til i get some results from you.

It's the S5's AFM that's the main intake bottleneck.

This looks like the wide mouth bottle I've been looking for.

and im tried of th bulk that is the S4 flapper

Two of the 929 AFM's I saw on e-bay were rectangular hole input, round output, flap type S4 style, and were also this big.

I can only guess at S4 plug compatability.

very interesting ... keep us updated on this please ..

what year did you use?

Mine runs lean enough, dont think my AFM's working right. Anywho the car runs and idles fine so im not messing with it in that department.

Many people say it but that's absolutely false. They base this assumption on a guess. Some people have the logic that because the cone is in the way that it is a restriction whereas the flapper moves aside and is not. Untrue. The cone may be in the way but it is very nicely shaped which is good for airflow. The flapper door style is always in the way. In other words the edge of it always causes alot of turbulence which decreases airflow. Airflow through the S4 afm is far less than it would be through a hole shaped the same size with smooth inlets and outlets and no edges to pass. I have flowbench tested each one in the past but sadly didn't save the numbers. I can tell you that the S5 does flow better though.

well let us know what the part number is of the afm that you are using. i am going to buy one up if i can find it.

Brian

I wonder if using some sort of resister or adjustment to the pot would let this work with a stock ECU. I would love to see someone flow both of these and compare resistance from one to the other at several diferent flow rates.

SureShot, always the thinker! :icon_tup:

Stop making assumptions you cannot prove objectively.

Airflow has to also travel with more delfection from the larger center plunger...

I'd like to see hard proof that it does flow more - flowbench anyone?

Else, I don't see any performance advantage since you're still trying to match airflow with fuel delivery.
So you're changing the meter size, but you still need to jack the signal down to match the airflow being delivered?


-Ted

i dont think this 929 AFM is going to do anything.

you do know hes going to use an afc to alter the signals right? jesus christ let the man tlk. yall alwase say it won work till someone goes and prioves your little theoretical assumtions wrong. its bigger and less restrictive. point blank.

Glad I am not the only one thinking this

But you have this huge vortex now in the middle of you air flow...which based on aero dynamics says that the larger AFM would actually hinder air flow and slow intake velocity.

So until this can actually be proved to do anything I am (and probably Ted as well) more than skeptical.

This is basic Fluid Dynamics 101.
Also, it breaks Newton's first law - the shortest route between two points is a straight line.
Think about it.


-Ted

I hope Icemark sticks around a while, this thread has huge ugly potential.

This is only partially true. And only one factor of many that would affect losses (resistance to flow).

My degree is in mechanical engineering, fluid flow was one of my main areas of study (gas turbine engines etc).

Air can only flow until it is sonic and at that point is direclty limited by cross sectional area. Is flow anywhere near sonic in this thing? No but it is almost certainly turbulent.

If the 929 flow meter truly has less resistance to opening, and a lager "bore" it may indeed flow with less losses, depending on how much are you are actually trying to stuff through it.

It all depends on what the reynolds number is (likely turbulent) and if turbulent it basically only depends on CFM and minnimum cross sectional area. As the differences between the two in shape are incosiquential when they are that minimal and we are talking turbulent flow.

it wont do anything.

Okay, now we're going into turbulent versus laminar...

But you're missing the point.

If this were an NA application where we're stuck with "0" ATM, then maybe you've got a point.
The problem is that we're talking about a turbo, so what's preventing you from turning the boost up?
If the AFM was truly a restriction, then a larger AFM would give you a performance advantage.
The reality is that it's not, especially with a stock or mildly modified mods that produce only mild power gains.

Unless you're maxing out the stock AFM (which I doubt you are), then and only then will a larger AFM would give you an advantage.
BUT, you're messing with an S-AFC anyways, which can dial down (or up) the signal, so show me where the advantage is?

If we're talking about a 300bhp+ engine, then maybe there is an advantage.
I'd still like to see solid, objective numbers rather than blurting out "it's better" conclusions.
If you're making over 300hp, a stand-alone EMS is highly recommened, and we wouldn't be having this conversation in the first place.

I'm assuming this thread is to stuff a 929 AFM on an FC turbo that's only making about 200hp.
Are you claiming just swapping the AFM (and adjusting the signal down) is magically going to give you 5? 10? 15? More power? Just because you swapped the AFM???
I'd really like to see proof of this rather than people just CLAIMING this is so.
You people need to go look up what a SCIENTIFIC PROOF is before blasting us critics - there's a reason why we don't agree with what any Tom, Dick, Harry claims on an online forum...


-Ted

I love details.
It sounds to me like this is mod equals "six of one ,half a dozen of the other".
(no differance at best)

Actually my S-AFC was showing the stock AFM at 100% at 6K RPM & 11 PSI boost.
That's what prompted me to look around.

My current S-AFC low map is -35@1000 -50@1500 -50@2500 -50 for the rest.
High map is -10@1000 -7@1500 -5@2500 -3@3500 -3 for the rest.
This is contrary to what I expected.
I expected more flow at the same signal voltage, which should lean it.
I was avoiding re-initializing the S-AFC, but now I think I should, so it can re-learn the ranges.

I should have it well enough tuned this weekend to go WOT at 11 PSI & see what the bigger AFM % is.

I'll tell you what...
Got a dyno close by to you?
I'll *PAY* for your two dyno runs with the stock versus 929 AFM just to see which makes more power.
Deal?


-Ted

Ted,
How does this sound?
First, I'd like to get the down pipe on. The stock turbo is choking at 6K.
Then I'll take the G-tech for before & after rides, to see if I may have a measurable difference.

The S-AFC tuning is the possible corrupting variable here.

If it looks promising, and you're still interested, I'll split the cost of a dyno test with you..

Sure!
Keep us updated or drop me a PM.
Good luck!


-Ted

It would be interesting to see a vacuum measurement between the turbo and the stock AFM vs. the turbo and the 929 AFM. Higher vacuum should equal more restriction.

think about it. it all makes sence. assuming it has the same exact spring inside it for tension, yet the aria that the air comes in contact is larger, then why wont it be eaiser?

amd infact, ill do thios little ditty msyelf. ill go out and buy one, andthen ill test it on a completly stock s4 engine ( no porting, just breathing modfs) a before and after and then maybee.. maybee well get siome answers?

Regardless of the pros/cons, there is another option to those that have a MAF that failed and already own an SAFC or equivalent. I'm on my 2nd AFM and keep a spare. They don't last forever and the salvage yards don't see to have them(or RX7s) laying around. If it flows more, great. If it doesn't make a power difference, who cares if you have it and it was cheap enough.

The engine would need to be tuned for both meters and not just run on the dyno for simple comparison.

Keep us informed with the butt dyno, the GTech, the 'feel' of the spool up/lag, and other personal opinions or measurements(like vacuum/boost/SAFC settings....). This, IMO, is just as important as the dyno.

What I can't stand is the, "I didn't think of it first attitude" here. So, you must prove that it works.
Why doesn't someone here proved that it doesn't work? It always easier to slam someone with an idea.
Its almost as bad as the 'its cost too much' so don't do it attitude.

We wouldn't have lightbulbs or electricity if someone, with an idea or thought, quit because of the negativity surrounding them.
Well, gotta run and light the kerosene lamp before it gets dark again.

BTW, what year 929's used that MAF? Anyone want to guess if other vehicles had the same/similar one? truck/minivan/millenium/.....????

OK this is where I come in. As a Vacuum Physicist, the term you're looking for is "conductance" the tubing will "conduct" x amount of flow or CFM. Conductance can be impeded by A) length B) ID C) Torr (the reverse of pressure for you Boost junkies) D) the bends in the tubing.

One thing that all of will not think of is the throttling fo the inlet. Your Conductance will rely totally on the smallest ID of any point. You could have an AFM as big a 55 Gallon Barrel but if your inlet flange is the same size as the throttle body then you haven't gained diddly. For Proof of my theory, refer to restrictor plate racing. The restrictor plate "throttles" the flow hence it equalizes the BHP output and the racers are all evenly matched for......( I hate restrictor plate racing). The Throttle body on the 13B (unless ported) would be the restriction no matter what size the AFM is.

As far as the turbulence is concerned, go back the Dynamic intake or Plenum design. Which many of you no more about than I care to learn.............

The car it came from: MAZDA 929 90-91 DOHC

In '69 I quit engineering & switched to programming, so I'm not an engineer, but I'm a good mechanic.
Before doing the before/after test I'm thinking about a better CAI also.

Off topic: The downpipe will have a remote cut out, so I will also be able to compare the stock mufflers to an OPEN down pipe.
I know cut outs are old school, but I just couldn't resist: zoom zoom / ZOOM ZOOM BAM!

True, you can offset the extra fuel from the 929 AFM with an SAFC, but won't that REALLY be screwing with your timing?

I did some quick measuremants. The stock AFM, close estimate, =~2.15". Thats 3.631 sq.in. Throttles are 1.772" (FSM). Thats 2.466 sq.in. Times three = 7.398 sq.in.

I think there is room for improvement here!


Working back from total TB area. It is = to a 3.069 dia. tube.

Actually, a ring 1/3 (really 3.14159...) bigger than the hole in the middle and the hole in the middle should both have the same cross-sectional area. Correct?

I haven't tried to get the measurements on the ring made by the plunger full back yet. Got to go.

it's very simple to measure if the 929 is less restrictive.

measure the pressure drop across the meters.

do this with a manometer, it won't cost you much and you can drive around with the two meters on the car, monitoring pressure drop at various loads

if the 929 demonstrates less pressure drop - it's better, no ifs ands or buts.

And then...

No, it's not that simple.
In terms of airflow, if you're going to take a raw cross sectional area, it's going to be totally wrong.

You need to factor in the big dildo in the middle of the damn thing, and this makes it slightly more complex to factor in maximum potential airflow.


-Ted

You engineers can make it as complicated as you want.

What I see is - it's bigger, and I had to dial down the S-AFC 40% to tune it.

I doubt is 40% bigger.
The spring resistance is almost identical between the two.
I expect some to the difference is the larger vane, so the same pressure drop will move it back more.
The same flow, through the larger hole, should move it back less.
Where that balance point is - we shall see.

My guess is, the pressure drop will be slightly less, and the flow headroom will be slightly more.

After I re-initialize the S-AFC, and work the vane so it re-learns the signal range, I'll do a WOT pull and display the max air flow %.
That will tell.

keep up to the good work

it's nice to see some innovation in here

Do the dyno asap. Use Ted to your advantage for the dyno time!

Again, what are you saying about "pressure"???? Wouldn't be any pressure....rather vacuum. Let me use laymens terms.....Inches of mercury.

After thinking about this for a day or so, the thing that probably is happening is that the AFM is sending an incorrect signal to your S-AFC causing the richness and your O2 sensor is picking it up.

Think for a minute That plunger just gets sucked back by the vacuum and then there is a positioning sensor that reads where the plunger is and send a signal to the CPU and richness adjustments are made to the injectors. You changing to the 929 AFM is just sending an incorrect signal to your S-AFC making you believe that you've done something hence your 40% number.

I'll bet if you check the the voltage against both AFCs that a certain amount of movement equates to a certain achieved voltage and that both are not identicle and without the factory specs You could spend 4 weeks trying to find the Delta between the two.

You have not increase airflow to your motor by any means. think......If you increased the amount of oxygen to your motor......wouldn't your O2 sensor pick up a lean reading?????

Furthering my point. and returning to the restrictor plate example, did you increase the ID of your throttle body?

did you even ponder the restrictor plate example??

Same difference, vacuum is still pressure in absolute terms. It's just when people are stuck in the context of relative to atmospheric pressure they start thinking vacuum is some magical thing that is vastly different from boost. They can both be described in terms of absolute pressure.

map sensor measures vacuum and boost, it's a manifold *absolute pressure* sensor.

all you need to measure is the pressure difference across the afm's to find which one is more restrictive @ operating CFM's you can do this on the car with a very cheap tool called a manometer.

theres nothing to argue about, put some instrumentation on the car and drive around with the different meters, come back with the one that showed less difference.


BTW dictionary definition of vacuum:
2. The condition of rarefaction, or reduction of pressure
below that of the atmosphere, in a vessel, as the
condenser of a steam engine, which is nearly exhausted of
air or steam, etc.; as, a vacuum of 26 inches of mercury,
or 13 pounds per square inch.


notice, *reduction of _pressure_* vacuum is still pressure, the only thing that makes it "vacuum" is it's relative *pressure* to the surrounding atmosphere. IT's still pressure!

No, Vacuum is not pressure............................760 torr

Vacuum is measured in torr, Mercury, Microns etc.......Never PSI. please rethink your theory. And remember a Cars engine is a large VACUUM pump.

Now that you completely ignored my earlier post concerning Conductance and the throttling effect of the smallest ID point at any given moment. I never said that the larger AFM from the 929 was less restrictive.

I did say that unless you have ported your throttle body and dynamic intake you could an AFM as large as a 55 gallon Drum and it would not make any difference. Your motor is still getting the same amount of airflow today as it did a week ago. And untill you open up any throttling IDs along the way.......your motor is still going to get the same amount of airflow today as well as any other day hereafter...........

back to the vacuum You really need to just think about a multi carbed motorcycle. Go to any motorcycle shop and they'll show a mercury Carb stick. This is use to synch multiple carbs based onthe amount of vacuum they are pulling. You adjust the carbs so that all the mercury levels are the same..............vacuum is not the same.......otherwise you could use a tire "pressure" guage to set carbs..

Don't feel bad 95% of the Engineers at JPL, Northrop-Grumman and Lockhead Martin Don't understand vacuum either.

Normal atmospheric pressure is defined as 1 atmosphere. 1 atm = 14.6956 psi = 760 torr

Based on the original Torricelli barometer design, one atmosphere of pressure will force the column of mercury (Hg) in a mercury barometer to a height of 760 millimeters. A pressure that causes the Hg column to rise 1 millimeter is called a torr (you may still see the term 1 mm Hg used; this has been replaced by the torr). 1 atm = 760 torr = 14.7 psi.

wow, you're really ignorant and stuck in your own views.

wikipedia:
A vacuum is a volume of space that is empty of matter and radiation, including air, so that gaseous pressure is much less than standard atmospheric pressure. The root of the word vacuum is the Latin word vacuus (pl. vacua) which means "empty," but space can never be perfectly empty. A perfect vacuum with a gaseous pressure of absolute zero is a philosophical concept with no physical reality; see sections below on Vacuum in Space and The Quantum Mechanical Vacuum.

oh look, they describe vacuum by it's relative PRESSURE to the atomspheric PRESSURE, looky looky, all that PRESSURE everywhere!

You're clearly full of it because if you knew any of the thingsy you claim to know you wouldnt pull the tire pressure gauge b.s. out of your ass, a tire pressure gauge measures pressure relative to atmosphere - with poor precision at that. An absolute pressure instrument will measure what you call 'vacuum' and what others here call 'boost' just the same, becaue they are simply different pressures.


http://en.wikipedia.org/wiki/Vacuum

The definition of a vacuum includes 'pressure'.