Cobalts SS banner
1 - 14 of 14 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter · #1 ·
Boost gauge in USA is measured in HG were as in Canada it is measured in kpa. What is the conversion? My mine reads 80-90 kpa, what is that in HG? Can some one please help? :confused:
 

·
Registered
Joined
·
57 Posts
yep 1psi = 6.89 kpa

So Turner427 12.5psi = 86.18kpa which is right where you say yours is reading :)
 

·
Registered
Joined
·
24 Posts
2K2CamaroSS said:
yep 1psi = 6.89 kpa

So Turner427 12.5psi = 86.18kpa which is right where you say yours is reading :)
you are correct sir also 14.7 psi is 1 atm and that equates to 101.4 KPA which equats 760 torr (mmHG)

isnt math fun! :cool:
 

·
Registered
Joined
·
158 Posts
what does "IN HG" stand for, i know autometer, i know psi, i know boost, but dont know what "IN HG" means on there
 

·
Registered
Joined
·
93 Posts
inches mercury (Hg is the atomic symbol)... like what you would read a barometer in. although I have no idea how that measurement plays into the guage

it's a pressure measurement
 

·
Registered
Joined
·
24 Posts
johnkb8 said:
what does "IN HG" stand for, i know autometer, i know psi, i know boost, but dont know what "IN HG" means on there
first off, a barometer is measure in mmHG (millimeters of mercury) not in inches, as a side note mmHG is out torr is in (same thing but a torr is named after the man who invented it, like watt, pascal, newton, ect....). also what is a measure of autometer? and just for kicks boost isnt exactly a measurement.....its a term. boost is a general term for any compressed gas in the engine thats over 1 ATM. boost is measure in something, ATM, psi, mmHG ect.

i dont wanna be a jerk or start anything just getting the correct info out to yah.

nick
 

·
Registered
Joined
·
162 Posts
nice_n_lo_silverado said:
.its a term. boost is a general term for any compressed gas in the engine thats over 1 ATM. boost is measure in something, ATM, psi, mmHG ect.
nick
1 ATM is a bit misleading as it seems to imply that the gauge measures against a set pressure. (pressure at sea level under standard conditions is the definition of an atmosphere). Your boost/vacuum gauge will measure Pounds per Square Inch Gauge (PSIG) over or under the local pressure which may be higher (Death Valley) or lower than the standard atmosphere.

So for another equally useless bit of trivia, your 'boost' gauge does not read out in PSI, but in PSIG. (no matter what it says on the legend)
 

·
Registered
Joined
·
24 Posts
this is true, but isnt a cumbustion chamber always at a set variable of pressure readings? never blew X and above Y (when working properly) if the engine were moved to higher and lwer altitudes i wouldnt think that the chambers pressure would be any different, if at higher elevations it would be making boost than.

correct me if im wrong ion this but this is what i thought....i knew?
 

·
Registered
Joined
·
162 Posts
nice_n_lo_silverado said:
this is true, but isnt a cumbustion chamber always at a set variable of pressure readings? never blew X and above Y (when working properly) if the engine were moved to higher and lwer altitudes i wouldnt think that the chambers pressure would be any different, if at higher elevations it would be making boost than.

correct me if im wrong ion this but this is what i thought....i knew?
Interesting question. In a n/a engine, the cylinder pressures will be lower when there is a lower ambient pressure as there will be less air mass drawn in on the intake stroke, thus less cylinder pressure on the compression stroke (both dynamic and static). In a forced induction motor it is a bit more murky. I suppose whatever type of relief valve was used to limit the upper boost limit would, for lack of a better phrase, 'pop off' at lower absolute pressures if the ambient pressure was lower than 1 ATM.

This would have it produce lower absolute pressure into the intake and, thus, lower cylinder pressures. Might get away with lower octane fuel if you get enough altitude, although I would not try it on my personal f/i vehicle.

My experience with turbo diesel engine generators (I oversee the installation of them) is that the output is relatively unaffected up to about 7000ft and then drops off (we have to de-rate the output). The turbo's will overcome any loss below that altitude and I surmise it is because they spool easier/faster in the thin air, but above that, they simply cannot cram enough mass (air) in fast enough. That is in a 4-pole e/g that runs at 1800 RPM at all times. It probably would be much worse in a gas engine that spins at 3 times that speed.

Anyone up high having trouble holding full boost?
 

·
Registered
Joined
·
24 Posts
hm...good points! id say i got proven wrong
 

·
Registered
Joined
·
24 Posts
hm...thinking about what i said im totally wrong! i dont know what i was thinking, i guess its bad to drink and do long division lol
 
1 - 14 of 14 Posts
Top