Cobb AccessPORT Discussion
04-02-2008, 11:36 AM
#1276
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In the discussions of Bernoulli's Principle, I mistakenly claimed that air behaves like a fluid. This is not entirely true. It has some of the properties of a fluid, but WILL compress (a fluid won't). Also, fluid wants to move in circular motions (see "wave action"). Air does too (see "tornadoes") in response to pressur differences, but fluid doesn't compress and air does. Air on the long side of a curved tube will accelerate faster than the air on the short side, but because of the difference in pressure from one side to the other, it will tend to continue to swirl afterwards (see "inertia" i.e. an object in motion... etc).
As you increase the size of a tube, with volume of flow remaining constant, velocity decreases. As velocity decreases, the character of the flow (swirls, eddies, pressure) all changes. As Kane points out, he has to DOUBLE the pressure applied to 1/4" hose to deliver the SAME amount of air to a diver as he would with 3/8ths inch hose. 1/4" to 3/8ths" is a very small difference, but over a 300 ft distance is quite remarkable.
All of this thinking makes my head hurt...
Bernoulli's Principle works because each molecule of fluid pulls the next right along with it, each seeking the path of least resistance, i.e. low pressure (see "venturi effect". Weber carbs owes their entire existence to this principle.
What does it all mean? I haven't the foggest clue!
As you increase the size of a tube, with volume of flow remaining constant, velocity decreases. As velocity decreases, the character of the flow (swirls, eddies, pressure) all changes. As Kane points out, he has to DOUBLE the pressure applied to 1/4" hose to deliver the SAME amount of air to a diver as he would with 3/8ths inch hose. 1/4" to 3/8ths" is a very small difference, but over a 300 ft distance is quite remarkable.
All of this thinking makes my head hurt...
Bernoulli's Principle works because each molecule of fluid pulls the next right along with it, each seeking the path of least resistance, i.e. low pressure (see "venturi effect". Weber carbs owes their entire existence to this principle.
What does it all mean? I haven't the foggest clue!
04-02-2008, 11:39 AM
#1277
Or start charging for the custom tunes.
The leangths you're going to are awesome, but really, you're out-of-the-box maps are more than anyone could really expect. All this tweaking and tuning, even doen remotely, has to be taking a LOT of time, and there's already enough customizability in your standard map set to cover most folks. The rest of us deserve to pay a bit more to be picky (I'm using "us" in the optimistic, I plan on knocking over a bank later in the week. If that goes well, I'll place my order
)
The leangths you're going to are awesome, but really, you're out-of-the-box maps are more than anyone could really expect. All this tweaking and tuning, even doen remotely, has to be taking a LOT of time, and there's already enough customizability in your standard map set to cover most folks. The rest of us deserve to pay a bit more to be picky (I'm using "us" in the optimistic, I plan on knocking over a bank later in the week. If that goes well, I'll place my order
)I am swamped. However, I consider every person that has purchased an AccessPORT from me to be to be part of a sort of personal tuning "Wiki".
Each change or update ultimately helps everyone, including myself.
Its kind of like the "open source" tuning that Lola was trying to do only without the "me giving him everything so that I only have the work and he gets the money" part.
I only need to sell another 50 of these things and I get the pink Lincoln Continental!
04-02-2008, 11:45 AM
#1279
Administrator
iTrader: (7)
^^ if you sell 100, does it comes it come with a Pettit SC?
04-02-2008, 11:49 AM
#1280
A quick note on STFT and LTFT:
I get this comment/question a lot, so let me address it here in brief.
Short Term Fuel Trim is an "instantaneous" value. It is all over the place and can be a value from +24 to - 24. The way I use it in helping you decide which flash to start with is NOT what it was intended for.
It is just an effective shortcut.
So, your idle STFT may be +/-2, but the value may go all over the map when you are driving. Some will see it jump up 10 - 12 when they hit the pedal or see it go to -12 when cruising at low speeds.
Ultimately, what matters is the Long Term Fuel Trim.
When I ask for the STFT to determine the flash "family", it is only the initial, instantaneous value - right after the first start up - at idle I am interested in. After driving the car a bit, the LTFT will start to "absorb" some of the STFT offset, making the STFT number smaller. You should watch for that and be aware that the sum of the two numbers will now affect your choice if you have waited too long to make your decision between "X_1b" and "X_2b".
A lot of factors go into the STFT and it is constantly changing. The LTFT is much more stable, but there are only a few values for it at different fixed load settings and it takes a while for it to establish.
If, after driving around for a bit, you find that your LTFT are big numbers in certain places, than you need to make adjustments and the best way to do that is to start over.
I sure hope not. Where would I put it? My storage area is already full and I don't think it will make a very good flower pot.
[[I am not anti-supercharger. It just sounds that way because it is such an easy target. Sorry to all the Pettit owners for the cheap joke. Void where prohibited.]]
I get this comment/question a lot, so let me address it here in brief.
Short Term Fuel Trim is an "instantaneous" value. It is all over the place and can be a value from +24 to - 24. The way I use it in helping you decide which flash to start with is NOT what it was intended for.
It is just an effective shortcut.
So, your idle STFT may be +/-2, but the value may go all over the map when you are driving. Some will see it jump up 10 - 12 when they hit the pedal or see it go to -12 when cruising at low speeds.
Ultimately, what matters is the Long Term Fuel Trim.
When I ask for the STFT to determine the flash "family", it is only the initial, instantaneous value - right after the first start up - at idle I am interested in. After driving the car a bit, the LTFT will start to "absorb" some of the STFT offset, making the STFT number smaller. You should watch for that and be aware that the sum of the two numbers will now affect your choice if you have waited too long to make your decision between "X_1b" and "X_2b".
A lot of factors go into the STFT and it is constantly changing. The LTFT is much more stable, but there are only a few values for it at different fixed load settings and it takes a while for it to establish.
If, after driving around for a bit, you find that your LTFT are big numbers in certain places, than you need to make adjustments and the best way to do that is to start over.
I sure hope not. Where would I put it? My storage area is already full and I don't think it will make a very good flower pot.
[[I am not anti-supercharger. It just sounds that way because it is such an easy target. Sorry to all the Pettit owners for the cheap joke. Void where prohibited.]]
Last edited by MazdaManiac; 04-02-2008 at 11:51 AM.
04-02-2008, 11:54 AM
#1281
btw Jeff, 2 days ago I flashed down to the stock 3 map (no a or b modification).
LTFT and STFT were 0 almost all the time during idle.
I'm still on the lean side and haven't been able to data log information for you, but I'm ok waiting till whenever you have time. The car runs flawlessly otherwise.
BTW, I too think the AP should be sold as you originally stated. Buying the AP from you gives the buyer the base maps for FI and NA.
Any custom tuning should cost extra. Also you haven't told me what I owe you for the intake. If this is how you're trying to run a business (giving crap away for free), you're doing a poor job my friend! lol
LTFT and STFT were 0 almost all the time during idle.
I'm still on the lean side and haven't been able to data log information for you, but I'm ok waiting till whenever you have time. The car runs flawlessly otherwise.
BTW, I too think the AP should be sold as you originally stated. Buying the AP from you gives the buyer the base maps for FI and NA.
Any custom tuning should cost extra. Also you haven't told me what I owe you for the intake. If this is how you're trying to run a business (giving crap away for free), you're doing a poor job my friend! lol
04-02-2008, 12:02 PM
#1283
Power!!
In the discussions of Bernoulli's Principle, I mistakenly claimed that air behaves like a fluid. This is not entirely true. It has some of the properties of a fluid, but WILL compress (a fluid won't). Also, fluid wants to move in circular motions (see "wave action"). Air does too (see "tornadoes") in response to pressur differences, but fluid doesn't compress and air does. Air on the long side of a curved tube will accelerate faster than the air on the short side, but because of the difference in pressure from one side to the other, it will tend to continue to swirl afterwards (see "inertia" i.e. an object in motion... etc).
As you increase the size of a tube, with volume of flow remaining constant, velocity decreases. As velocity decreases, the character of the flow (swirls, eddies, pressure) all changes. As Kane points out, he has to DOUBLE the pressure applied to 1/4" hose to deliver the SAME amount of air to a diver as he would with 3/8ths inch hose. 1/4" to 3/8ths" is a very small difference, but over a 300 ft distance is quite remarkable.
All of this thinking makes my head hurt...
Bernoulli's Principle works because each molecule of fluid pulls the next right along with it, each seeking the path of least resistance, i.e. low pressure (see "venturi effect". Weber carbs owes their entire existence to this principle.
What does it all mean? I haven't the foggest clue!
As you increase the size of a tube, with volume of flow remaining constant, velocity decreases. As velocity decreases, the character of the flow (swirls, eddies, pressure) all changes. As Kane points out, he has to DOUBLE the pressure applied to 1/4" hose to deliver the SAME amount of air to a diver as he would with 3/8ths inch hose. 1/4" to 3/8ths" is a very small difference, but over a 300 ft distance is quite remarkable.
All of this thinking makes my head hurt...
Bernoulli's Principle works because each molecule of fluid pulls the next right along with it, each seeking the path of least resistance, i.e. low pressure (see "venturi effect". Weber carbs owes their entire existence to this principle.
What does it all mean? I haven't the foggest clue!
04-02-2008, 12:13 PM
#1286
04-02-2008, 12:29 PM
#1289
Administrator
iTrader: (7)
04-02-2008, 12:34 PM
#1291
RX-8s Official Cool Guy
04-02-2008, 12:34 PM
#1292
Administrator
iTrader: (7)
why didn't you just place the order through his website like most of us? 
04-02-2008, 12:44 PM
#1294
Administrator
iTrader: (7)
speaking of orders: Jeff, you should be getting something in the mail today. Thanks.
I haven't checked my email in a few days; did you send anything to me? If not, it's cool... I won't mess with the AP till this weekend and I know you've been busy
I haven't checked my email in a few days; did you send anything to me? If not, it's cool... I won't mess with the AP till this weekend and I know you've been busy
04-02-2008, 01:00 PM
#1296
RX-8s Official Cool Guy
:o I know how to order off of the Website... but I had asked him some important questions via PM and until those questions are answered I don't want to get the AP then later I found out it won't work for my application.
04-02-2008, 01:33 PM
#1299
Administrator
iTrader: (7)
I'll send you another one, I'm sure your poor inbox has seen better days. No huge rush. Thanks.