Hi All
I am trying to determine the fuel cut point/s of my 92 FD. I have found a set of readings, but they are for Absolute Manifold Pressure, which is the boost gauge reading PLUS the atmosphere.
So, whats the Atmosphere PSi in London please, anyone?
uh? Atmospheric pressure at sea level shoulds, on average be 0.
However, that\'s not strictly true - on a boost gauge it will be zero. But on average, it is actually 1bar (Or one thousand milibars!) This varies slightly due to weathewr conditions, etc - but use 1000 (i.e. 1bar - 14.7PSI) as the figure to go from.
14.7 PSI is standard atmospheric pressure at seal level
If your gauge is reading absolute pressure, then it should show 14.7 PSI with the engine turned off.
If it\'s reading Zero with the engine turned off then the gauge is reading " Gauge pressure" which is more common in industry. The tyre pump gauge at your local garage reads "Gauge pressure", which is the pressure above atmospheric.
Atmospheric pressure decreases by approximately 1.0 psi for every 2,343 feet. For the London Area 14.7 PSI is good enough
Well, how abvout that for a more comprehensive answer! :)
Quote from: nikpuh? Atmospheric pressure at sea level shoulds, on average be 0.
Err if it was really zero your body would explode !
Quote from: nikpHowever, that\'s not strictly true - on a boost gauge it will be zero. But on average, it is actually 1bar (Or one thousand milibars!) This varies slightly due to weather conditions, etc - but use 1000 (i.e. 1bar - 14.7PSI) as the figure to go from.
So, our boost gauges are calibrated to show zero for the Atmoshperic pressure, yes?
Ok, I found a website that says 1 Bar, or 1 kg/cm2, which equals 14.2 PSI.
Well, I meant that most people when talking about air pressure refer to it as zero. Perhaps i wasn\'t too precise when explaining it...but i did clarify my meaning in the next paragraph! :p
...plus, we\'d only explode if we had normal air in our lungs - at a pressure above that of the air pressure outside our lungs! So we would necassarily explode! So ner! :p
Quote from: nikp...plus, we\'d only explode if we had normal air in our lungs - at a pressure above that of the air pressure outside our lungs! So we would necassarily explode! So ner! :p
Not so!!!!
Whats the pressure in your veins?
NER! :flamed
Quote from: nikp...plus, we\'d only explode if we had normal air in our lungs - at a pressure above that of the air pressure outside our lungs! So we would necassarily explode! So ner! :p
Wait , we agree because you said "So we would necassarily explode!"
:p :p :p :p :rollin
Poo to you! Not fair! I blame it on monday morning syndrome! :(
Lol !!!!
After all that I discovered that the website did have them in PSI!
What you see here is RPM then Absolute Pressure, then Boost Pressure in the 3rd Column. These are supposed to be the point at which the standard FD ECU will cut fuel.
1000 26.5 11.8
1500 26.5 11.8
2000 26.5 11.8
2500 26.5 11.8
3000 26.9 12.2
3500 27.1 12.4
4000 27.5 12.8
4500 28.0 13.3
5000 26.9 12.2
5500 26.0 11.3
6000 25.8 11.1
6500 25.4 10.7
7000 25.4 10.7
I am not sure I believe them, though, because my car is spiking much higher than these readings and I havent hit Fuel cut yet. Meantime I am looking for and analogue Air Fuel meter to check my 02 readings before I do anymore testing to try and solve my boost problem.
My car was hitting 1.1 bar spike after the decat, still no fuel cut! Stock ECU - no sign of a fuel cut defender.
Are those figures for all Rx7\'s or the USA version? You\'re not planning to check your air fuel ratio with a narrow band A/F guage are you?
So what\'s your boost problem?
I agree with those figures being suspect, my FD is running stock gear and it\'s hitting 1 bar with no fuel cut! wether it\'s different between GB, Jap & USA cars I don\'t know??
Jono
Yes, my figures are from a US website, so our cars might be different.
Been away and lost track of this thread.
looking at MARTINY\'s post of 26th September 2005, 03:45 PM, the difference between the second and third columns is a consistent 14.7
So the second column is the absolute presssure + boost pressure and the third column is the boost pressure only.
Engine techies are interested in atmospheric pressure as the14.7 psi differential between the atmosphere and a vacuum is the most driving pressure avaiable to push a fuel mixture into the cylinders (of old tech cars)