Can someone please explain the Bar setups for FI?
07-19-2009, 09:41 PM
#1
Can someone please explain the Bar setups for FI? I have been searching and trying to figure it out and have vague answers but I was wondering if you guys could explain what the different Bar setups are when you go FI and delete the MAF?
Thanks
Thanks
07-19-2009, 09:53 PM
#2
1 bar is standard atmospheric pressure. if your engine has zero vacuum, and zero boost, it is operating at 1 bar.
2 bar is twice the standard atmospheric pressure. 2 bar is 14.5psi above ambient pressure, or 14.5 pounds of "boost"
3 bar is triple the atmospheric pressure, or about 29psi above ambient pressure.
gauge pressure (psig) is what is referred to as "boost" because its a measurement over ambient pressure. absolute pressure (psia) is pressure above a complete vacuum. a naturally aspirated engine operates between 0-1bar since it will never get into boost. therefore, factory N/A cars only have a 1 bar map
1 bar = 14.5psia = 0psig
2bar = 29psia = 14.5psig
3bar = 43.5psia = 29psig
psia is absolute pressure, psig is gauge pressure. unless otherwise noted, 99.9% of the time people say "psi" they mean psig
ok, i hope this helps.. i don't know how many other ways to explain this
*edit* it should be noted that 1 bar is by definition 100kPa (14.5psi) while a normal more accurate "standard" atmosphere at sea level is closer to 14.7psi(a) or 101.3kPa or 101.3bar. also, it should be noted that not all 2 or 3 bar MAP sensors are exactly 200kPa or 300kPa respectively. you should check the specs on the specific sensor you are using for tuning purposes.
2 bar is twice the standard atmospheric pressure. 2 bar is 14.5psi above ambient pressure, or 14.5 pounds of "boost"
3 bar is triple the atmospheric pressure, or about 29psi above ambient pressure.
gauge pressure (psig) is what is referred to as "boost" because its a measurement over ambient pressure. absolute pressure (psia) is pressure above a complete vacuum. a naturally aspirated engine operates between 0-1bar since it will never get into boost. therefore, factory N/A cars only have a 1 bar map
1 bar = 14.5psia = 0psig
2bar = 29psia = 14.5psig
3bar = 43.5psia = 29psig
psia is absolute pressure, psig is gauge pressure. unless otherwise noted, 99.9% of the time people say "psi" they mean psig
ok, i hope this helps.. i don't know how many other ways to explain this
*edit* it should be noted that 1 bar is by definition 100kPa (14.5psi) while a normal more accurate "standard" atmosphere at sea level is closer to 14.7psi(a) or 101.3kPa or 101.3bar. also, it should be noted that not all 2 or 3 bar MAP sensors are exactly 200kPa or 300kPa respectively. you should check the specs on the specific sensor you are using for tuning purposes.
Last edited by ChevyChad; 07-19-2009 at 10:00 PM.
07-19-2009, 10:09 PM
#3
1 bar is standard atmospheric pressure. if your engine has zero vacuum, and zero boost, it is operating at 1 bar.
2 bar is twice the standard atmospheric pressure. 2 bar is 14.5psi above ambient pressure, or 14.5 pounds of "boost"
3 bar is triple the atmospheric pressure, or about 29psi above ambient pressure.
gauge pressure (psig) is what is referred to as "boost" because its a measurement over ambient pressure. absolute pressure (psia) is pressure above a complete vacuum. a naturally aspirated engine operates between 0-1bar since it will never get into boost. therefore, factory N/A cars only have a 1 bar map
1 bar = 14.5psia = 0psig
2bar = 29psia = 14.5psig
3bar = 43.5psia = 29psig
psia is absolute pressure, psig is gauge pressure. unless otherwise noted, 99.9% of the time people say "psi" they mean psig
ok, i hope this helps.. i don't know how many other ways to explain this
*edit* it should be noted that 1 bar is by definition 100kPa (14.5psi) while a normal more accurate "standard" atmosphere at sea level is closer to 14.7psi(a) or 101.3kPa or 101.3bar. also, it should be noted that not all 2 or 3 bar MAP sensors are exactly 200kPa or 300kPa respectively. you should check the specs on the specific sensor you are using for tuning purposes.
2 bar is twice the standard atmospheric pressure. 2 bar is 14.5psi above ambient pressure, or 14.5 pounds of "boost"
3 bar is triple the atmospheric pressure, or about 29psi above ambient pressure.
gauge pressure (psig) is what is referred to as "boost" because its a measurement over ambient pressure. absolute pressure (psia) is pressure above a complete vacuum. a naturally aspirated engine operates between 0-1bar since it will never get into boost. therefore, factory N/A cars only have a 1 bar map
1 bar = 14.5psia = 0psig
2bar = 29psia = 14.5psig
3bar = 43.5psia = 29psig
psia is absolute pressure, psig is gauge pressure. unless otherwise noted, 99.9% of the time people say "psi" they mean psig
ok, i hope this helps.. i don't know how many other ways to explain this
*edit* it should be noted that 1 bar is by definition 100kPa (14.5psi) while a normal more accurate "standard" atmosphere at sea level is closer to 14.7psi(a) or 101.3kPa or 101.3bar. also, it should be noted that not all 2 or 3 bar MAP sensors are exactly 200kPa or 300kPa respectively. you should check the specs on the specific sensor you are using for tuning purposes.
But I guess that doesn't make sense to me because the guys that procharge their cars don't need to upgrade to the 2 bar MAP correct?
Maybe I don't get it...
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07-20-2009, 07:09 AM
#9
You really need to do some more searching man. This question has been answered many times. Basically, on a stock MAP sensor, ofcourse, the MAP sensor will be maxed out. The tune adds fuel based on the amount of air coming in thru the MAF. It can do this for up to 500-550rwhp, then the MAF will get maxed out as well. Once that happens, the tune is then adding fuel based on RPM alone since the MAP and MAF are both maxed out. That is pretty much a bandaid way to go about things. Once you max your MAF out, you'd be better off switching to a SD tune so that it adds fuel based on boost rather than RPM like it would a maxed out MAF tune. This is where the 2 and 3 bar MAPs come into play.
07-20-2009, 08:08 AM
#10
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You really need to do some more searching man. This question has been answered many times. Basically, on a stock MAP sensor, ofcourse, the MAP sensor will be maxed out. The tune adds fuel based on the amount of air coming in thru the MAF. It can do this for up to 500-550rwhp, then the MAF will get maxed out as well. Once that happens, the tune is then adding fuel based on RPM alone since the MAP and MAF are both maxed out. That is pretty much a bandaid way to go about things. Once you max your MAF out, you'd be better off switching to a SD tune so that it adds fuel based on boost rather than RPM like it would a maxed out MAF tune. This is where the 2 and 3 bar MAPs come into play.
07-20-2009, 01:16 PM
#11
You really need to do some more searching man. This question has been answered many times. Basically, on a stock MAP sensor, ofcourse, the MAP sensor will be maxed out. The tune adds fuel based on the amount of air coming in thru the MAF. It can do this for up to 500-550rwhp, then the MAF will get maxed out as well. Once that happens, the tune is then adding fuel based on RPM alone since the MAP and MAF are both maxed out. That is pretty much a bandaid way to go about things. Once you max your MAF out, you'd be better off switching to a SD tune so that it adds fuel based on boost rather than RPM like it would a maxed out MAF tune. This is where the 2 and 3 bar MAPs come into play.
Regardless, awesome man, thanks for the explanation. You cleared it up perfectly for me.
Last edited by 98RedBird; 07-20-2009 at 01:21 PM.
glad i could help guys.. we really need more stickies here in the FI forum to clear up so many of these questions because you are right, the search is hard sometimes when you don't know the keywords to search for. 
