Turbo tuning ?s
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Car: 1989 pontiac firebird trans am gta
Engine: 355
Transmission: 700r4
Axle/Gears: 327:1 9 bolt
Turbo tuning ?s
I dont know if I should put this in the DFI forum or here. I am building a twin turbo 355 and have been looking at different fuel management systems. My question is, MSD sells MAP sensors and they have 3 available. 1 is for N/A and it says it is a 1 bar. The next is for turbo up 20 psi and it is a 2 bar and the last is for 30 psi and it is a 3 bar. What I want to know is what do they mean x amount of bars. Any help will be greatly appreciated.
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Car: 1982 Trans-Am
Engine: 355 w/ ported 416s
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shot in the dark but, a bar refers to one atmospheric pressure. I think 1bar = 1atm = 14.7 PSI pressure. (easy to remember, stoich is also 14.7
)
If that's what they mean....
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If that's what they mean....
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Car: 1989 pontiac firebird trans am gta
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That is what I thought it would mean but when I thought some more I was not sure. Anything over 14.7 psi will be like entering a second atmosphere. Then 29.4 would be the third. It sounds good. I am not sure
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Engine: 3xx ci tubo
Transmission: 4L60E & 4L80E
Originally Posted by 355gta
Anything over 14.7 psi will be like entering a second atmosphere.
For all practical purposes, free air is 14.7 PSI at sea level, 2bar is about 2x atmosphere pressure or 2*14.7, and 2-bar is 3x atmosphere pressure or 3*14.7PSI = 44.1 PSI. An air pressure gauge reads 0 PSI at 14.7 PSI of atmosphere pressure. Boost is relative to fee air or 14.7 PSI of atm. pressure.
That is why people refer to psia and psig. psig = psia -14.7. The 2bar or 3bar is refering to psia.
So, relative to free air then 2bar is 29.4 - 14.7 = 14.7 PSI OVER atmosphere pressure (what an air pressure gauge would read). 3bar would read 3*14.7 - 14.7 = 29.4 PSI.
Those are generic rough calcs. Go to the Garrett turbo website in the Tech area for a more detailed and accurate summary.
Basically, use a 2bar for up to 15 PSI of boost and a 3bar for up to 30 PSI of boost.
#5
You're confusing bar with atm (atmospheres) and PSIA with PSIG.
PSIA – Pounds per Square Inch ABSOLUTE – where 0 is 0, no atmosphere at all
PSIG – Pounds per Square Inch GAUGE – where 0 is normal atmospheric pressure, 14.7psi
PSIG = PSIA – 14.7psi
1atm = 14.7psi
1bar = 14.5psi (don’t ask why, I don’t know, it’s stupid, I know, probably invented by someone that was on a mountain and due to lower pressure was not getting enough O2 to his brain)
A 1 bar map _should_ read 5VDC at 0psig, a 2 bar map _should_ read 5VDC at 14.5psig and a 3 bar map _should_ read 5VDC at 29psig, but some are odd, like the Honda 1 bar maps can put out 5V at somewhere around 7psig.
PSIA – Pounds per Square Inch ABSOLUTE – where 0 is 0, no atmosphere at all
PSIG – Pounds per Square Inch GAUGE – where 0 is normal atmospheric pressure, 14.7psi
PSIG = PSIA – 14.7psi
1atm = 14.7psi
1bar = 14.5psi (don’t ask why, I don’t know, it’s stupid, I know, probably invented by someone that was on a mountain and due to lower pressure was not getting enough O2 to his brain)
A 1 bar map _should_ read 5VDC at 0psig, a 2 bar map _should_ read 5VDC at 14.5psig and a 3 bar map _should_ read 5VDC at 29psig, but some are odd, like the Honda 1 bar maps can put out 5V at somewhere around 7psig.
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