Cobb AccessPORT Discussion
03-31-2008, 09:20 PM
#1176
Unregistered User
iTrader: (1)
Join Date: Oct 2004
Location: Spring/The Woodlands
Posts: 235
Likes: 0
Received 0 Likes
on
0 Posts
That's exactly what I thought, but I've had detonation in this car before. That detonation event was accompanied with loss of power and that unmistakable sound that says this is gonna hurt. This was more of a metallic rattling sound. Strange.
03-31-2008, 09:20 PM
#1177
has money, but unsure
Join Date: Mar 2008
Location: find bombs, afghanistan
Posts: 386
Likes: 0
Received 0 Likes
on
0 Posts
what AFR's are you running in boost?
03-31-2008, 09:23 PM
#1178
in 3rd gear it's 12-13, in the higher gears it appears to be 11-12. I have yet to go over about 6.5k rpm since the CAI install.
Here's a short example I recently made (low boost): http://ircimages.com/afr.wmv
Here's a short example I recently made (low boost): http://ircimages.com/afr.wmv
03-31-2008, 09:27 PM
#1179
I have way more power with the current setup than I did before the CAI and 10 afr's - it's insane at 11 psi and just half throttle, but I am not going to be comfortable till the AFR is somewhere between 10.5 to 11.2.
03-31-2008, 09:30 PM
#1180
has money, but unsure
Join Date: Mar 2008
Location: find bombs, afghanistan
Posts: 386
Likes: 0
Received 0 Likes
on
0 Posts
in 3rd gear it's 12-13, in the higher gears it appears to be 11-12. I have yet to go over about 6.5k rpm since the CAI install.
Here's a short example I recently made (low boost): http://ircimages.com/afr.wmv
Here's a short example I recently made (low boost): http://ircimages.com/afr.wmv
11.5 = Approximate rich best torque at WOT
12.2 = Safe best power at WOT
13.3 = Approximate lean best torque
03-31-2008, 09:44 PM
#1183
has money, but unsure
Join Date: Mar 2008
Location: find bombs, afghanistan
Posts: 386
Likes: 0
Received 0 Likes
on
0 Posts
meth system? overkill
if you are worried about intake charge cooling, just upgrade the I/C
03-31-2008, 09:52 PM
#1184
i'd love to replace my intercooler (Not that I really need to upgrade, but it's warm in FL in the summers and cooler is better). I just don't want to guess and have something that doesn't fit. And now I need to make sure any replacement doesn't go behind the low impact bumper cause my CAI is routed behind it.
03-31-2008, 10:22 PM
#1186
Registered
Join Date: Sep 2006
Location: Madison, WI
Posts: 1,202
Likes: 0
Received 0 Likes
on
0 Posts
Well I got the AP. I know MM is away for the next few days, so should I load the base Cobb Map and see how things go? I don't even know what I'm looking for. Just so you guys know I have the MS CAI, MS exhuast, and RP supercat. I'm not to worried about fuel mileage, I just want to get the most out of my car as possible.
03-31-2008, 10:37 PM
#1187
Hell, I get home from work and there is big o'l disscussion.
I've always thought of insulating the MAF pipe. Thats last on my list.
I pretty close to doing that now. Not many other things I can do for NA.
I still have a few tricks.
03-31-2008, 11:02 PM
#1188
Registered
Join Date: May 2006
Location: Charlotte, NC
Posts: 528
Likes: 0
Received 0 Likes
on
0 Posts
03-31-2008, 11:03 PM
#1189
Msql and Celronx, I have been seeing the samething with N/A
I think the explaination is throttle position and load.
Those are slightly changing because your foot is moving, I know I'm pedal to the metal so how can that happen.
I haven't studied it enough with the data logs to see if the A/F is changing due to slight postion differance in the throttle.
If the throttle remains the same and the A/F bounces then perhaps the load is changing due to wind resistance.
Back on the MAF issue, if velocity is effecting the MAF more than pressure, what about the position of the sensor? The question is:
Is the velocity decrease and sensor loaction enough to overide the pressure increase using a largertube size with FI applications.
I think the answer to this question is Yes.
I think the explaination is throttle position and load.
Those are slightly changing because your foot is moving, I know I'm pedal to the metal so how can that happen.
I haven't studied it enough with the data logs to see if the A/F is changing due to slight postion differance in the throttle.
If the throttle remains the same and the A/F bounces then perhaps the load is changing due to wind resistance.
Back on the MAF issue, if velocity is effecting the MAF more than pressure, what about the position of the sensor? The question is:
Is the velocity decrease and sensor loaction enough to overide the pressure increase using a largertube size with FI applications.
I think the answer to this question is Yes.
Last edited by Razz1; 03-31-2008 at 11:05 PM.
03-31-2008, 11:06 PM
#1190
Registered
I tend to be gullible when it comes to Wikipedia, since I don't know much. Now I'm really confused. So my initial hunch to side w/ dannobre is the current "correct" consensus?
Anyway, sorry to add to the topic diversion.
I'm hoping to contribute, if I can, to this thread after I receive the product.
Anyway, sorry to add to the topic diversion.
I'm hoping to contribute, if I can, to this thread after I receive the product.
04-01-2008, 12:11 AM
#1191
Too.... much..... reading! HAHA.
Short version = Dan is MORE right than the stagnant pressure folks; but both of you are somewhat right; however the pressure changes you are talking about are very very very very small.
For example - when we flow 150 PSI through 300' of 3/8 ID diameter hose; we get 135 PSI to the divers (roughly) at 8 SCFM. When we need to flow the same 135 PSI to a diver through a 1/4 hose; we have to push 300 PSI. So flow velocity and total capable volume play WAY more of a roll than extra pressure from a larger tube.
In addition; if the MAF were that sensitive to changes in size; then a blow through setup would immediately peg once you entered boost.
Short version = Dan is MORE right than the stagnant pressure folks; but both of you are somewhat right; however the pressure changes you are talking about are very very very very small.
For example - when we flow 150 PSI through 300' of 3/8 ID diameter hose; we get 135 PSI to the divers (roughly) at 8 SCFM. When we need to flow the same 135 PSI to a diver through a 1/4 hose; we have to push 300 PSI. So flow velocity and total capable volume play WAY more of a roll than extra pressure from a larger tube.
In addition; if the MAF were that sensitive to changes in size; then a blow through setup would immediately peg once you entered boost.
04-01-2008, 01:11 AM
#1193
Banned
Join Date: Feb 2008
Location: Suwanee, GA
Posts: 347
Likes: 0
Received 0 Likes
on
0 Posts
bernoulli stuff, the whole airfoil thing.
the top of the wing is "longer" so the air travels over it faster. Higher velocity = lower pressure. the bottom of the wing is "shorter" so air travels over it more slowly. Lower velocity = higher pressure. This generates lift...
It's kind of an abstract thing. Another example is blowing over the top of something, it creates a lower pressure and can suck liquid through the orifice. If you have an air compressor, a thin piece of tubing/needle (like to inflate a football), and a jar of water it's easy to do. Take the needle and put it in the jar of water, spray air over the needle and it will make a nice atomized mist. This form of atomizer is also found in perfume bottles...
the top of the wing is "longer" so the air travels over it faster. Higher velocity = lower pressure. the bottom of the wing is "shorter" so air travels over it more slowly. Lower velocity = higher pressure. This generates lift...
It's kind of an abstract thing. Another example is blowing over the top of something, it creates a lower pressure and can suck liquid through the orifice. If you have an air compressor, a thin piece of tubing/needle (like to inflate a football), and a jar of water it's easy to do. Take the needle and put it in the jar of water, spray air over the needle and it will make a nice atomized mist. This form of atomizer is also found in perfume bottles...
Last edited by FloppinNachos; 04-01-2008 at 01:19 AM.
04-01-2008, 02:37 AM
#1197
Banned
Join Date: Feb 2008
Location: Suwanee, GA
Posts: 347
Likes: 0
Received 0 Likes
on
0 Posts
I dunno what to say, the atomizer experiment helped me understand it kinda.
I still don't fully understand what exactly is happening, only that it does and it definitely doesn't have many good analogies to describe it...
I still don't fully understand what exactly is happening, only that it does and it definitely doesn't have many good analogies to describe it...
04-01-2008, 06:31 AM
#1198
I remember now why I didn't consider this principle all that complicated when I was learning it in school, and it was because of this statement on Mitchell's website;
"The sum of the static and dynamic pressures remains constant along the pipe."
Earlier I asked what was meant by "pressure". If I am undertsanding correctly, "static" pressure is the one we usually visualize when discussing pressures but "dynamic" pressures are what might be more commonly called "velocities". There are also references to static pressures and ram pressures, with ram pressure also being velocity.
Now I re-get it(after having forgotten it many years ago).
Damn this website and damn you guys!
"The sum of the static and dynamic pressures remains constant along the pipe."
Earlier I asked what was meant by "pressure". If I am undertsanding correctly, "static" pressure is the one we usually visualize when discussing pressures but "dynamic" pressures are what might be more commonly called "velocities". There are also references to static pressures and ram pressures, with ram pressure also being velocity.
Now I re-get it(after having forgotten it many years ago).
Damn this website and damn you guys!
. Yeah I guess Aristotle did give classes
04-01-2008, 07:15 AM
#1199
Registered
iTrader: (1)
Join Date: May 2003
Location: PA
Posts: 3,754
Likes: 0
Received 0 Likes
on
0 Posts
bernoulli stuff, the whole airfoil thing.
the top of the wing is "longer" so the air travels over it faster. Higher velocity = lower pressure. the bottom of the wing is "shorter" so air travels over it more slowly. Lower velocity = higher pressure. This generates lift...
the top of the wing is "longer" so the air travels over it faster. Higher velocity = lower pressure. the bottom of the wing is "shorter" so air travels over it more slowly. Lower velocity = higher pressure. This generates lift...
When you take an advanced fluid dynamics class, you learn Bernouli is given too much credit and the Kutta-Joukowski Theorem involving circulation around an airfloil is what really produces lift and the dP predicted by Bernouli can not make a modern airplane fly.
04-01-2008, 07:51 AM
#1200
Registered
Join Date: Sep 2006
Location: Madison, WI
Posts: 1,202
Likes: 0
Received 0 Likes
on
0 Posts
I hate to interupt the flow of this thread but I got the AP. I know MM is away for the next few days, in the meantime should I load the base Cobb Map and see how things go? I don't even know what I'm looking for. Just so you guys know I have the MS CAI, MS exhuast, and RP supercat.