Please Help.. How much HG is in one PSI? (Or vice versa..) I know psi and bar for boost, but have no idea what the conversion for HG - Psi is.. and it seems every online conversion is different!?!?!? HELP!!!
lol...am I losing it..or does this mean that 10lbs of boost (psi) is 517 HG?!?!
If you wanted to make a conversion from “psi” (psia) to “in of Hg” you need to consider ATM in the equation. The conversion is:
1 psi = 2.036 in of Hg
Also consider that 1 ATM is 14.7 psi
Therefore,
If you want to know what 10 psig is equivalent to in “in of Hg” you most convert to “psi”:
10 psig = 24.7 psi
24.7psi*2.036 in of Hg/psi = 50.29 in of Hg (1.68 ATM)
If you wanted to make a conversion from “psi” (psia) to “in of Hg” you need to consider ATM in the equation. The conversion is:
1 psi = 2.036 in of Hg
Also consider that 1 ATM is 14.7 psi
Therefore,
If you want to know what 10 psig is equivalent to in “in of Hg” you most convert to “psi”:
10 psig = 24.7 psi
24.7psi*2.036 in of Hg/psi = 50.29 in of Hg (1.68 ATM)
wow...so a boost/vacuum gauge that reads to 10 hgs in boost , and down to 30 in vacuum wont really be of use in my car at all since i'm somewhere above 10psi.... that 10HG gauge would be maxxed out once i passed around 5 lbs of boost i'm guessing....damn..hahah
The OP was asking about conversions so the calculation given in my previous post above was in absolute values but a gauge would read relative to atmosphere for our applications. So, if we want to talk about gauges for our cars, we do not measure pressure in “In Hg”, we measure pressure in “psi” and vacuum in “In Hg” all with atmosphere as reference. A gauge reading of 0 is equal to 14.7psia (1 ATM). When the gauge is reading 10 psi, you are actually at 24.7psia (1.68 ATM). A gauge reading of 20 In Hg is a vacuum and is 4.9psia (0.3 ATM). A typical vac/boost gauge will be from 30 In Hg to 15 psi (approx 0 ATM – 2 ATM) or 30 In Hg to 30 psi (approx 0 ATM – 3 ATM). At idle you should be at approx 20 In Hg and will see a peak on the gauge of your boost at 11 psi when you are at peek rpm under load.
so...a gauge like this....would be only effective if i was runing 5 psig or less (approx)...
http://cgi.ebay.com/ebaymotors/25-S...ccessories&hash=item5ad90b3891#ht_1670wt_1165
Tha is correct. This gauge does not even go low enough for the Vac. Are you looking for gauges?
But yeah, so what is a gauge like that one for?!
I think we're arguing the same point here, but I think we both were getting thrown off by the other's explanations. The poster implied that both boost AND vacuum are being measured in Inches of Hg on his particular gauge. You were explaining off a typical boost gauge and I was giving a non-auto specific pressure answer.
Either way, if my interpretation of the posts is correct, I'm fairly surprised the OP came across an automotive boost gauge that has a positive pressure in inches of Hg since, well, almost no one measures anything except atmospheric pressure in inches of mercury...