Want less intake restriction? - A 929 AFM works!
02-15-06, 02:14 AM
#26
Lives on the Forum
Originally Posted by RockLobster
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.
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.
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
02-15-06, 08:10 AM
#28
Seduced by the DARK SIDE
Thread Starter
Join Date: Apr 2001
Location: Orange Park FL (near Jax)
Posts: 7,323
Likes: 0
Received 2 Likes
on
2 Posts
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.
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.
02-15-06, 08:55 AM
#30
Seduced by the DARK SIDE
Thread Starter
Join Date: Apr 2001
Location: Orange Park FL (near Jax)
Posts: 7,323
Likes: 0
Received 2 Likes
on
2 Posts
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..
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..
02-15-06, 09:30 AM
#32
Engine, Not Motor
iTrader: (1)
Join Date: Feb 2001
Location: London, Ontario, Canada
Posts: 29,789
Likes: 0
Received 108 Likes
on
91 Posts
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.
02-15-06, 09:33 AM
#33
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?
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?
02-15-06, 11:16 AM
#34
Opinions are like........
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/.....????
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/.....????
02-15-06, 11:37 AM
#35
Carter 2.0
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.............
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.............
Last edited by jhammons01; 02-15-06 at 11:44 AM.
02-15-06, 11:55 AM
#36
Seduced by the DARK SIDE
Thread Starter
Join Date: Apr 2001
Location: Orange Park FL (near Jax)
Posts: 7,323
Likes: 0
Received 2 Likes
on
2 Posts
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!
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!
02-15-06, 07:39 PM
#38
Red Pill Dealer
iTrader: (10)
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.
I think there is room for improvement here!
Working back from total TB area. It is = to a 3.069 dia. tube.
02-15-06, 07:45 PM
#39
Red Pill Dealer
iTrader: (10)
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.
I haven't tried to get the measurements on the ring made by the plunger full back yet. Got to go.
02-15-06, 07:54 PM
#40
The mystery of the prize.
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.
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.
02-16-06, 04:52 AM
#41
Lives on the Forum
Originally Posted by TonyD89
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.
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.
I haven't tried to get the measurements on the ring made by the plunger full back yet. Got to go.
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 ***** in the middle of the damn thing, and this makes it slightly more complex to factor in maximum potential airflow.
-Ted
02-16-06, 07:22 AM
#42
Seduced by the DARK SIDE
Thread Starter
Join Date: Apr 2001
Location: Orange Park FL (near Jax)
Posts: 7,323
Likes: 0
Received 2 Likes
on
2 Posts
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.
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.
02-16-06, 12:16 PM
#45
Carter 2.0
Originally Posted by pengarufoo
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.
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.
02-16-06, 12:26 PM
#46
Carter 2.0
Originally Posted by SureShot
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%.
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%.
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??
02-16-06, 12:44 PM
#47
The mystery of the prize.
Originally Posted by jhammons01
Again, what are you saying about "pressure"???? Wouldn't be any pressure....rather vacuum. Let me use laymens terms.....Inches of mercury.
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!
Last edited by pengarufoo; 02-16-06 at 12:49 PM.
02-16-06, 01:04 PM
#48
Carter 2.0
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.
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.
02-16-06, 01:10 PM
#49
Carter 2.0
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.
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.
02-16-06, 02:21 PM
#50
The mystery of the prize.
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 ***, 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'.
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 ***, 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'.