bar=psi?
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10-30-2001, 08:52 AM
#17
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Re: bar=psi? (falconGSR)
The pressure ratio is the total absolute pressure produced by the turbo divided by atomspheric pressure. Absolute pressure means the amount of pressure above nothing at all. Nothing at all is zero absolute, so atomspheric is 14.7 absolute. 2 psi boost becomes 16.7 absolute, 5 psi is 19.7 absolute, and so on. Total absolute pressure is then whatever the gauge reads plus 14.7. The pressure ratio thus becomes a reflection of the number of atomspheres of pressure generated.
Pressure ratio= (14.7 + boost)/14.7
Ex: for 5 psi
PR= (14.7 + 5)/14.7 = 1.34
In this example approximately 34% more air will go into the engine than the engine could have consumed by itself.
PR= (14.7 + 12)/14.7= 1.82
Here approximately 82% more air will be going through the system. Pressure is also measured in bar, short for barometric ( 1bar=14.7 psi).
-From our friend Corky Bell
Pressure ratio= (14.7 + boost)/14.7
Ex: for 5 psi
PR= (14.7 + 5)/14.7 = 1.34
In this example approximately 34% more air will go into the engine than the engine could have consumed by itself.
PR= (14.7 + 12)/14.7= 1.82
Here approximately 82% more air will be going through the system. Pressure is also measured in bar, short for barometric ( 1bar=14.7 psi).
-From our friend Corky Bell
10-30-2001, 09:04 AM
#18
Honda-Tech Member
Re: bar=psi? (98hx99b18c)
Thanks 98hx, I always thought that bar itself stood for "barometric", i.e. static barometric pressure, hence 1bar is 100% atmospheric pressure, which is 14.7psi at sea level. Less at higher altitudes. So .5bar = 7.35psi being that .5 or 50% bar = 1/2 barometric/atmospheric pressure at sea level which is 14.7psi. (14.7psi x 50% = 7.35psi is the same as 1bar x .5bar = .5 bar) I know it seems confusing but reading it over leads you to see it's really easy actually.
[Modified by VTC_CiViC, 1:05 PM 10/30/2001]
[Modified by VTC_CiViC, 1:05 PM 10/30/2001]
10-30-2001, 10:16 AM
#19
Re: bar=psi? (VTC_CiViC)
OK, so how many inches (or mm of mercury) is equal to "standard" atmospheric pressure?
30" of water (or Hg i.e., mercury, I forget which) = one atmosphere (one bar, 14.7 psi) ?
30" of water (or Hg i.e., mercury, I forget which) = one atmosphere (one bar, 14.7 psi) ?
10-30-2001, 01:07 PM
#20
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Relieve all your headaches here:
http://www.joshmadison.com/software/...t/download.asp
I'll bet none of you knew that so many different units existed.
I'll bet none of you knew that so many different units existed.
10-30-2001, 02:19 PM
#21
Honda-Tech Member
Re: Relieve all your headaches here: (mercury)
why do people keep turning this into an argument? This is getting worse than the Quaife/KAAZ bumble-clot conversations. Art gave the correct answer a long time ago.
atmospheric pressure = 14.7psi
1bar = 14.5 psi
1kgcm = 14.22 psi
atmospheric pressure = 14.7psi
1bar = 14.5 psi
1kgcm = 14.22 psi
10-30-2001, 03:28 PM
#22
Honda-Tech Member
Re: Relieve all your headaches here: (drealgsr)
I use this neat java webpage which has Bar = kg/cm2 = psi converter.
http://www.worldwidemetric.com/metcal.htm
works really well...
liam
http://www.worldwidemetric.com/metcal.htm
works really well...
liam
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