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-   -   Which to believe? SAFC or BOOST GUAGE!!! (https://www.homemadeturbo.com/forced-induction-7/believe-safc-boost-guage-44592/)

b20accord 08-17-2005 03:26 AM

Which to believe? SAFC or BOOST GUAGE!!!
 
Well ive been making a few runs and my boost guage reads about 7 psi, but my safc will show about 27 kpa which converts to 3.91psi??? Which one should i believe? My safc or my boost guage?? My boost guage has given me crap in the past so thats why i dont know which one to believe???

JDMFantasy2K 08-17-2005 09:06 AM

Re: Which to believe? SAFC or BOOST GUAGE!!!
 
i've been noticing the same thing on my vafc. I'd def trust the boost gauge first since it is mechanical and the vafc is just trying to make a reading from the MAP sensor (i believe).

USS 08-17-2005 10:24 AM

Re: Which to believe? SAFC or BOOST GUAGE!!!
 

Originally Posted by b20accord
Well ive been making a few runs and my boost guage reads about 7 psi, but my safc will show about 27 kpa which converts to 3.91psi??? Which one should i believe? My safc or my boost guage?? My boost guage has given me crap in the past so thats why i dont know which one to believe???

Map sensors usually have a 0-5v range in which they read vacuum and boost. I think your SAFC is calibrated for your map sensor.

sohc_mshue 08-17-2005 10:34 AM

Re: Which to believe? SAFC or BOOST GUAGE!!!
 
Yea 27kPa is about what you should read at idle. About -21.97 in/HG

MikeJ-2009 08-17-2005 03:35 PM

Re: Which to believe? SAFC or BOOST GUAGE!!!
 
I noticed a 2-3 psi difference between my old boost gauge and vafc. Then I went to the dyno and the dyno read 2-3 psi more than either of them.


Everything is wrong. >:D

bumblezc 08-17-2005 03:48 PM

Re: Which to believe? SAFC or BOOST GUAGE!!!
 
Samething with my boostgauge and Laptop, I trust the laptop seeing as it reads from the map sensor, and that what the ECU uses for mapping.

Reddy 08-17-2005 04:49 PM

Re: Which to believe? SAFC or BOOST GUAGE!!!
 
I've had 3 different readings from my AFC, boost gauge and boost controller. I trust the boost controller the most

b20accord 08-17-2005 06:10 PM

Re: Which to believe? SAFC or BOOST GUAGE!!!
 
damn, lol. I really dont know which to believe now lol. I think i might just go with my boost guage considering thats what it is specifically for lol. Thanks for the help guys.

45psi 08-18-2005 03:12 AM

Re: Which to believe? SAFC or BOOST GUAGE!!!
 
add them both together and divide by two

Tom-Guy 08-18-2005 10:01 AM

Re: Which to believe? SAFC or BOOST GUAGE!!!
 
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 blowjob next. It's been a minute. ???

mik101 08-18-2005 01:05 PM

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 blowjob next. It's been a minute. ???

Well said.

ComputerJLT 08-18-2005 11:08 PM

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

b20accord 08-18-2005 11:29 PM

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

ooooo! Ok didnt think about that! Good info bro. So i should just trust my boost guage!

45psi 08-19-2005 03:41 PM

Re: Which to believe? SAFC or BOOST GUAGE!!!
 
are you stupid? ^^

b20accord 08-19-2005 04:35 PM

Re: Which to believe? SAFC or BOOST GUAGE!!!
 

Originally Posted by 45psi
are you stupid? ^^

Why the ---- did you say that???

2highpsi 08-19-2005 09:12 PM

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.


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