Which to believe? SAFC or BOOST GUAGE!!!
08-18-2005, 01:05 PM
#11
0.5 BAR
Join Date: Aug 2005
Posts: 67
Re: Which to believe? SAFC or BOOST GUAGE!!!
Originally Posted by Joseph Davis
You can't trust a mechanical gauge, not unless it's calibrated lab equipment. Prepare to pay some jack, and it's not a service grade gauge meant to be knocked about and vibrated a lot. Unless you *really* pay some jack.
You can't - wholly - trust the MAP sensor based reading as a lot of stuff can throw that off, too. Wierd voltage/resistance quirks in your wiring. Tolerance/calibration of the MAP sensor itself.
Personally, I pay the most attention to what the ECU logs tell me. While I doubt their exact calibrations for reasons stated above, I know exactly what timing and fuel values the ECU is operating off of. ~3 psi variance means jack ----, so does "how much boost you run, dog." I'm worried about whether or not the system performs consistently, hits the desired psi figure without variance or uncontrolled boost creep.
I'm also worried about when I get a ******* next. It's been a minute.
You can't - wholly - trust the MAP sensor based reading as a lot of stuff can throw that off, too. Wierd voltage/resistance quirks in your wiring. Tolerance/calibration of the MAP sensor itself.
Personally, I pay the most attention to what the ECU logs tell me. While I doubt their exact calibrations for reasons stated above, I know exactly what timing and fuel values the ECU is operating off of. ~3 psi variance means jack ----, so does "how much boost you run, dog." I'm worried about whether or not the system performs consistently, hits the desired psi figure without variance or uncontrolled boost creep.
I'm also worried about when I get a ******* next. It's been a minute.
08-18-2005, 11:08 PM
#12
1.5 BAR
Join Date: Feb 2004
Posts: 1,039
Re: Which to believe? SAFC or BOOST GUAGE!!!
also keep in mind that the honda MAP sensor is ABSOLUTE; meaning it reads 0psi at sea level and vaccum at elevation.
the AFC sees that pressure and your boost gauge is RELATIVE; meaning it takes it's base of 0psi whereever you are. so if you're at 5000' elevation 10psi of boost may only be +5psi over sea level
the AFC sees that pressure and your boost gauge is RELATIVE; meaning it takes it's base of 0psi whereever you are. so if you're at 5000' elevation 10psi of boost may only be +5psi over sea level
08-18-2005, 11:29 PM
#13
1.5 BAR
Thread Starter
Join Date: Jan 2005
Posts: 665
Re: Which to believe? SAFC or BOOST GUAGE!!!
Originally Posted by ComputerJLT
also keep in mind that the honda MAP sensor is ABSOLUTE; meaning it reads 0psi at sea level and vaccum at elevation.
the AFC sees that pressure and your boost gauge is RELATIVE; meaning it takes it's base of 0psi whereever you are. so if you're at 5000' elevation 10psi of boost may only be +5psi over sea level
the AFC sees that pressure and your boost gauge is RELATIVE; meaning it takes it's base of 0psi whereever you are. so if you're at 5000' elevation 10psi of boost may only be +5psi over sea level
08-19-2005, 09:12 PM
#16
0.5 BAR
Join Date: Aug 2005
Posts: 145
Re: Which to believe? SAFC or BOOST GUAGE!!!
he just told u that the map sensor reads absolute values and that the boost gauge will read differently depending on where you're at, aka it wont be accurate. 
i've seen this firsthand, the wastegate being set at 9psi and my gauge seeing 12psi at different elevations, whereas it wont go over 8 where i live.
i've seen this firsthand, the wastegate being set at 9psi and my gauge seeing 12psi at different elevations, whereas it wont go over 8 where i live.
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