SureShot

OK, I just plugged it in, dialed down the S-AFC and it worked.

Now you guys have me curious about the AFM voltages.
That should be easy to test.
I'll see how they compare tonight.

jhammons01

dude, these aren't MY views. I am just telling you what is and what ain't. pressure is the opposite of vacuum. Deal with it.

First off, who writes Wikipedia???? who edits it for mistakes. Sure the word pressure is in there but typically when referring to anything less than Atmoshperic pressure we use the term Vacuum. I only corrected your term.

Officially:
Although the Latin word Vacuum means "Empty" the object of vacuum techniques is far from being spaces without matter. At the lowest pressures which can be obtained by modern pumping methods there are still hundreds of molecules in cm3 of evacuated space
According to the definition or the American Vacuum Society (which I am a member in good standing) the term "vacuum" refers to a givin space filled with gas at pressures below atmoshperic, i.e. having a density of molecules less than about 2.5 x 10(19) molecules cm3.
In general term "vacuum" includes nowadays about 19 orders of magnatude of pressure (or Densities) below that corresponding to the standard atmosphere and is refered to as vacuum. The lower the limit of the range is continously decreasing, as the vacuum technology improves its pumping and measuring techniques
ref American Physics society, Vacuum Technology, A. Roth, Third edition Published in 1996 and used today in Classrooms and Labs all across the free world.

Please don't call these "my" beliefs as I am not near the physisist that Mr. Roth is. I am just relaying......to you.....what is and what isn't.

You may continue being ButtHurt.

pengarufoo

You just agreed with me.

you can't define vacuum without the word pressure, vacuum *IS* pressure.

man your own words:

torr
n : a unit of pressure equal to 0.001316 atmosphere; named after
Torricelli [syn: {millimeter of mercury}, {mm Hg}]

torr == a unit of pressure


that tool you described in laymans terms for syncing carbs is a manometer.

manometer
n : a pressure gauge for comparing pressures of a gas


do you see vacuum anywhere here?

all vacuum is pressure, not all pressure is vacuum.

when describing the vacuum or boost in the context of an internal combustion engine one can simply use the term 'pressure', which is exactly what I did. You use a manometer to measure the pressure difference across the flow meter to see how restrictive it is at those flow levels. That pressure may be vacuum, or boost, either way it's still pressure.

jhammons01

Reading comprehension eludes you.

jhammons01

Not to mention Boost or Forced induction and Natural aspiration are.........opposite.

jhammons01

Let's use another form of measurement to illustrate how rediculous you sound.

Let's say I have NO money in my wallet and I owe you $2. and I spout off that I [i[have[/i] money. Then you ask for the $2 dollors in which case I grab for my wallet. We all know (because I just told you) that I have NO money in my wallet. I hand you nothing saying that I am paying you yet you see NO money. You (somehow finding your sanity) say......there's nothing in my hand in which case I reply "Yes there is money there.

It's so simple.......I have less than zero dollars in my wallet commonly referred to as overdrawn or Broke or in debt. That aspect you will clearly agree with me is the opposite of rich, wealthy, loaded, payday!!!

Why can't realize that anything less than atmoshpere is correctly referred to as..........................vacuum.

Syonyk

... I'm going with pengarufoo here.

Vacuum is simply less pressure than ambient. It's still pressure.

The difference between your wallet analogy and pressure is that, at "0psi" (14.7psi absolute), there's still a lot of pressure.

-=Russ=-

TonyD89

iTrader: (10)

Hate to interupt the love-fest here, but I want to clarify my observations on the AFM.

I know there is a cone in the middle, even at full open.

There is a rule of thumb that says increasing the dia. of a pipe by 1/3 increases its flow rate 2x. Doubles it.

Place the original dia. in the new (1/3 bigger) dia.

The ring created is responsible for increasing the volume. Since it doubles it, wouldn't that make it eguall in cross-sectional area?

One needs to measure the OD and the ID of the ring at full open, calculate the area before they can say it is causing a restriction.

I know cross-sectional area is an over simplification. But I believe it is a good start. I also know bends and length of tube cause friction of the stream and effect flow rate.

I have to go in a bit again but I will try to come up with measurements and values later.

RoughRex

ok... This sounds like an argument between someone who thinks like an engineer (jhammons01) and someone who thinks like a technician (pengarufoo).

Personally, I think like a tech.

I think that the point pengarufoo is trying to make is:

1. Measure vacuum/ air pressure (it's semantics ppl) at WOT between the AFM and turbo.

2. IF the 929 AFM shows less vacuum than the stock box...then it is less restrictive to air flow and will allow the turbo to operate more efficiently instead of fighting with the stock AFM to pull in air.

Please correct me if I'm wrong here....but don't argue with me over semantics.

scathcart

You really think that the throttle body acts as a restrictor plate, and that making no changes to the intake track in front of or behind the throttle body make any changes to total airflow?

That is one of the dumbest thing I have ever heard. One thing I have learned about my fellow engineers: they lack common sense.

According to you, changing to a conular intake is useless, since the only restriction that matters is the throttle body.
Same with media porting the intake runners. Makes no difference since the TB is the only restriction that matters.
Putting mufflers in series doesn't reduce exhaust flow either; only the smallest muffler will act as any restriction. In fact, changing the downpipe and catback is completely useless, since the turbocharger itself is the largest restriction to airflow.


Did you all get that? Modding your car is completely useless until you change the throttle body.

A restriction placed in series with another restriction will cause a total increase in resistance, and a total decrease in airflow. Try it on a flowbench.

You're completely wrong on your definition of vacuum, too. That's why those 95% of engineers also think you're an idiot.

TonyD89

iTrader: (10)

I measured the outlet of the AFM as far as I could tell it is about 2.85" dia. at the rear cone. Using Pi(r)2 to get cross-section, then subtracting the front cone area, gives an anular area of ~2.748 sq. in.

2.748 sq. in. is a lot less than the inlet to the AFM area of 3.631 sq. in.

Maybe the AFM needs a constantly decressing flow rate to work.

Think about this.

The device would not work without a pressure drop. No vacuum behind the cone, it would not move back-wards against SPRING PRESSURE.

Hmmm... Spring pressure. Don't springs need more force as there compression increases? Maybe that is why the AFM tunnel gets smaller.

Just some stuff to chew on.

I just have to believe there is something to be gained by a larger AFM. Based upon the fact that the AFM inlets cross-section is ~3.631 in. sq. and the throttle body inlet is equal to 7.398 in. sq. !!

jon88se

By tricking the ECU so much with the SAFC (40%) aren't you really screwing with the timing curve? Last time I checked, every adjustment with an SAFC has an effect on timing as well...

This usually isn't a major concern for fine tuning, but since an SAFC only adjusts +/- 50% from stock I certainly wouldn't do it unless you're logging with a wideband.

pengarufoo

Ignoring all the discussion wether vacuum is pressure or not, it's failry obvious that the AFM takes energy to open. Regardless of what the size of your throttle is.

If the AFM is being moved by the air flowing through it, the engine is working harder to pull the air past this necessary *RESTRICTION* (AKA pumping loss) than say... a straight unimpeded pipe - or a less restrictive meter. If you can make this restriction less significant, you will see improved power, even without changing the throttle body. Of course, the difference between one AFM and another is going to be relatively minor, but if you were to switch to say speed/density like a haltech or microtech.... you would lose the AFM altogether with a much more significant potential gain in power.

Not even considering the added pumping losses introduced by the AFM, consider the effects on air density the *pressure drop* across the meter has on performance @ WOT, this is true for either NA or turbocharged cars.

Reducing pressure drop across the entire intake tract @ WOT is key to making more power, at the throttle, flow meter, air filter, valves, ports, or ducts. The trick is doing this without compromising velocity (don't just make everything huge).

I'm interested in seeing some relative comparisons of the two flow meters on the car taken with a simple manometer, it will be enough to tell you if there is merit in doing this modification.

RETed

Last time I checked the imperical formula, it airflow (well, fluid flow) potential increased ^4 relative to increase in diameter?
So 2x diameter = 16x potential airflow?


I dunno why you keep insisting this is true.
It is NOT.
You're ignoring the fact that the majority of the airflow flows though the CENTER of the passage.
Sticking a ***** in the CENTER of the passage takes away the path of most potential for airflow.


Wrong.

Grossly oversimplified and on the verge of being totally false...
90-degree bends are like a 37x drop versus a straight pipe...it's a big restriction.


-Ted

RETed

You're already wrong about the AFM, and now you're wrong on the TB.
You're totally ignoring the fact about the BUTTERFLIES in the middle of each bore!
Come on dude, you really need to take some application classes for fluid dynamics, cause the high school math doesn't cut it in this case...


-Ted

SirCygnus

iTrader: (1)

but in this case, will it work, or wont it. will it net power? or wont it? yall need to shut up and stop playing footsies i swear.

SexInDaRex

there are some damn nerds up in here. It's impressive!

rotarygod

iTrader: (1)

Fluid dynamics classes (or claiming to have taken them) apparently didn't teach anyone here jack ****. All I see is speculation with nothing to back it up. Typical, especially coming from a certain person who always asks for proof from others! I will say that the afm is the single biggest restriction in the intake. You'll pick up about 10% in total airflow increase by removing it completely. This is why porting your manifolds does nothing for power as long as the afm is still there. Power increase follows airflow gain in percentage fairly closely (but not entirely). Go buy or build a flowbench sometime and get real world experience involved. I know what I've personally seen on the bench and could really care less who believes what. It doesn't change anything though and the answer is still the same.

jhammons01

I find it amazing that you.......scathcart.........jumps and claims total donminant knowledge over the American Vacuum society and the American Physical Society, as well as all Academia inthe free world. Damn I guess they should have asked you to define vacuum becuase the way those pointy headed PhDs did isn't up to your standards. Please, tell us (the AVS and the APS) where to contact you to get the "Correct" definition. Now, don't pull anything outa your ***.......I (at least) provided references to the source of my definition.......a far cry from anything you have attempted to do.

For the record, My defintion of vacuum, which you seem to have overlooked, comes from American Vacuum Society, "Vacuum Technology" Written by A. Roth Former Deputy Director and Head of Department of Vacuum Technology, Soreq Nuclear Research Center and is published in The New York, Lausanne, Amsterdam, Oxford, Shannon, Tokyo and Elsevier.

The passage that I transcribed for you is found on page "1" Chapter "1" in The introduction!!!!! You don't even need to read any further than the very first page.

Oh wait......the mighty Scathcart form the RX7 Club pwnes A. Roth and all acadamia.....cause he can pound his chest louder!! Quick call Caltech and NASA, We got the next Einstien posting here

Dude, you really jumped off into that time

jhammons01

And just for fun let's poke fun at your example. Let's say that you Want to add a larger diameter down pipe. You think the larger diameter downpipe is going to add that much when you still have 13 year old clogged Stock Cat in the system? I'll answer it fo you.....No. The exhaust flow is still restricted by the cat. Hence the CFM is directly porportianate to the smallest diameter. Why can't you accept that simple premise???

Four other people have posted plenty of facts that back up my theory and you Chest pounders dismiss it as if science means nothing. You "Techs" are so ready to throw any science out the window if goes against your beloved beliefs.

Well, let me let you in on a secret. We pointy headed MEs EEs BSs etc. are techs that (gasp) went to school!!!!!! And learned a bit more than what they teach you in High School Automechanics. A Bachelor in Science is higher degree than being ASE certified.

Very Rarely do I pull the Physicist Card out of the Deck cause it seems a bit heavy for a Auto forum, but when you start talking about the very thing (vacuum) that earned me the Title of Physicist I feel I have something to contribute but only for the sake of SHARING my knowledge for your enlightenment. And what do I get?? Chest pounders.......

jhammons01

let me show that conductance and pumping speed are measured in the same units and both refer to similar concepts of a pipe's or pump's quality -- its ability to let gas move through it. To make use of these qualities we must have a clear understanding of the how conductances combine to give an effective conductance and how pumping speed and conductances are combined to give an effective pumping speed.

Combining Conductances in Series

They are added as reciprocals. (Readers who know electronics will immediately recognize the addition formula for series capacitors.)

1/Ctotal = 1/C1 + 1/C2 + 1/C3 + 1/C4 + 1/C5 + 1/C6

take the following collection of vacuum components and calculate the effective conductance if we connect them together in series:

Trap - 120 L/sec (C1)
Tube - 230 L/sec (C2)
Valve - 1400 L/sec (C3)
Elbow - 187 L/sec (C4)
Tube - 330 L/sec (C5)
Bend - 200 L/sec (C6)

The total conductance is given by

1/Ctotal = 1/120 + 1/230 + 1/1400 + 1/187 + 1/330 + 1/200
1/Ctotal = 0.0083 + 0.0043 + 0.0007 + 0.0053 + 0.003 + 0.005
1/Ctotal = 0.02677
Ctotal = 1/ 0.02677
Ctotal = 37.3 L/sec

First, notice that the total conductance is a whole lot less than any individual conductance. Second, don't be alarmed by the tedious intermediate steps. These calculations are a snap if you use a scientific calculator that can take reciprocals and add the result to the last number in the temporary store. Third, for the startling reality of adding conductances, look at the table. Here, just two conductances, one fixed at 10 L/sec, are added together. The result demonstrates a critical rule -- in series conductances the smallest rules.

Conductance
C1 Conductance
C2 Total Conductance
1/(1/C1 + 1/C2)
10 10 5 L/sec
10 100 9.1 L/sec
10 1000 9.9 L/sec
10 10,000 9.99 L/sec
10 100,000 9.999 L/sec
10 1,000,000 9.9999 L/sec

Combining Conductances and Pumping Speeds

Since pumping speeds are also measured in volumetric flow units, for conductance calculations, a pump is indistinguishable from a conductance. Indeed, the table above makes much better sense if we assume that Conductance C2 isn't a conductance at all but is a pump. Now, the table shows what happens when we attach successively higher pumping speed pumps to a skinny 10 L/sec tube connected to the chamber. The Total Conductance now becomes the effective pumping speed from the chamber

If the pump is a small drag pump with 10 L/sec pumping speed, the effective pumping speed from the chamber will be half that of the pump's nominal values. If the pump is a high priced turbo with a pumping speed of 1,000 L/sec, the effective pumping speed from the chamber is 9.9 L/sec. That skinny tube has thrown away ~99% of the nominal pumping speed. The smallest conductance rules indeed!

The waste gets even crazier if you happened to have a 1,000,000 L/sec monster cryo pump. But you already have the picture.

Conductances in Parallel

Using two conductances simultaneously between two chambers is not a common occurrence but we should understand how to calculate the numbers when it does happen. The arithmetic is even easier than above. As an example, we will use two tubes in parallel, the first 1800 L/sec and the second 2300 L/sec. The total conductance is given by:

Ctotal = C1 + C2
Ctotal = 1800 + 2300
Ctotal = 4100 L/sec

A more likely condition is a chamber that has two separate pumping ports, each connected to a different pump, for which we wish to calculate the total effective pumping speed. As an example, let us assume our chamber has a 400 L/sec ion pump connected by a 1000 L/sec port and 1500 L/sec Ti sublimation pump connected by a 500 L/sec port.

Ion Pump 1/Effective Pumping Speed = 1/400 + 1/1000
EPS = 286 L/sec

Ti Sub Pump 1/EPS = 1/1500 + 1/500
EPS = 375 L/sec

Total Effective Pumping Speed from Chamber
TEPS = 286 + 375
TEPS = 662 L/sec

jhammons01

Scathcart, I'll finish with this.

Pengerufoo and I are having a civil discussion about Scientific principles and terms. Nobody was being rude or condescending. However disagreable we were nobody called names until your dumbass walked in.

How many more examples of SCIENTIFIC facts will I have to post before you slink back under your rock in shame for calling me a dumbass??? Cause believe me Your dumbass comments are right up there on post #60 for all to see. Let me remind you. I posted an exact Definition from the utmost authority on Vacuum and Physics and you the Mighty Scathcart on the RX7 forum said it was wrong.....

why was it wrong???? How was it wrong??? Dollars to donuts you will never address that fact that YOU were proven wrong and further showing your ignorance called me a Dumbass.

Guess what? I got so many sources for this WELL PROVEN FACT I could keep posting them for hours. As a matter of fact I going to post a new source to support my position EVERDAY for the next week.....just so the thread stays on top reminding you of your ignorance.

SureShot

After reading through the above discussion, the above comment stands out.

My timing is stock, and so far- not a single knock.
I guess the timing trim for boost & revs is keeping me out of trouble.

FWIW I'm a cheapskate 2nd gen owner with one daily driver RX-7, so I'm working with only a narrow band AFR gauge.
It's like walking in a fog toward a cliff. You take small steps, and stay prepared to back up quickly.

Last nights testing was pre-empted by some home maintenance.
The voltage tests will be easy.
I may be able to rig a crude flow bench with a shop vac and an old precision aircraft boost gauge.

iceblue

There is so much argument amount TB, Plates, AFM , Cone. It don't matter how big you make one of them. You will never flow or produce more flow then the largest bottle neck in your system. Weather it be the TB plates or the AFM cone, it don't matter.

I see we have flow tested the AFM, have you flow tested the intake runners and TB and intake? What were the numbers in comparison?

There is no point in puting something on that flows say 200cfm if your intake runner ports only flow 160CFM. You will have got the same amount of flow by using a engineerd 160CFM match

SureShot

This is the same reasoning we use for replacing the stock air filter with a high flow cone filter.
You go after whatever is the next major bottleneck, one at a time.
My previous bottleneck was the AFM.
Next is the "Home Depot" TID.
Next is the CAI.

I already ported the motor and port matched the LIM when I did the rebuild.
The down pipe & cut out parts are all in, so barring a rain-out, I'll have it installed this weekend.

A little here, a little there, & pretty soon you're making more power.