Resolved vac pressure at idle in KPA or BAR??

[GstRacer]

can some one tell me what your vac. pressure is at in bar at idle

 

[Violater101]

This can also depend on whether you have your balance shafts removed and or have cams. Before I had cams and was pretty much stock, I was around 18psi vacuum at idle which is about the norm (1.22 bar).

 

[nine5raptor]

Originally posted by Violater101
This can also depend on whether you have your balance shafts removed and or have cams. Before I had cams and was pretty much stock, I was around 18psi vacuum at idle which is about the norm (1.22 bar).

Should be -9 psi or 18 in. Hg or -0.61 Bar 0.39 Bar abs. or thereabouts

 

[Violater101]

Originally posted by nine5raptor
Should be -9 psi or 18 in. Hg or -0.61 Bar 0.39 Bar abs. or thereabouts

As for the psi, I was going by my autometer gauge and I believe its in PSI or is is HG? If its displayed in HG, then okay 18. I have a Greddy guage now and don't really mess with reading it.

 

[nine5raptor]

Originally posted by Violater101
As for the psi, I was going by my autometer gauge and I believe its in PSI or is is HG? If its displayed in HG, then okay 18. I have a Greddy guage now and don't really mess with reading it.

Yeah, your vac side is in inches of Mercury. If it were -18psi, it would be more than a complete vacuum

 

[spyderman]

Vacuum is measured in inches of mercury (Hg) and boost is measured in PSI or Bar. 1 Bar=14.7 psi which is equivilant to atmospheric at sea level. I average 18 to 20 Hg @ idle on my 4G63. If you are down below 12 then start looking for vacuum leaks or valve seal problems.

 

[steve]

I find this come in handy when you need to convert units.
http://www.convert-me.com/en/convert/pressure

Steve

 

[nine5raptor]

or

www.onlineconversion.com

 

[trevnasty]

ok now if you remove some emissons vac line will that give you and diff reading on you boost/vac gauge my gauge 50 hg at idle so do i have a massive boost leak or is it becuse of all the emissons vac line have been removed please help thanks

 

[steve]

ok now if you remove some emissons vac line will that give you and diff reading on you boost/vac gauge my gauge 50 hg at idle so do i have a massive boost leak or is it becuse of all the emissons vac line have been removed please help

I think you're misreading your gauge. It's not technically possible on earth to have 50 in hg vacuum.

 

[crimsondragon]

I think you're misreading your gauge. It's not technically possible on earth to have 50 in hg vacuum.

This sounds like a fun fact. Do explain further.

 

[steve]

You can't pump off more than 1 atm (1.01 bar) until you reach 0 and can't go any lower. On planets with atmospheres the average pressure will differ from ours. So on Saturn it would be something like 1.39 bar and on Mars something like 0.00675 bar.

 

[trevnasty]

I think you're misreading your gauge. It's not technically possible on earth to have 50 in hg vacuum.

maybe my gauge is broken but i just cheacked it agian it 45 hg the gauge reads in 5 hg dash marks and it on dash mark from 50 so whats do you think broken gague

 

[steve]

maybe my gauge is broken but i just cheacked it agian it 45 hg the gauge reads in 5 hg dash marks and it on dash mark from 50 so whats do you think broken gague

Maybe, but I still think it's user error since unless you lived on Saturn or Jupiter there would be no reason to make a gauge that read than much relative vacuum.

Who's gauge is it.

Given your altitude your normal idle vacuum is going to be less than the 18 in hg factor spec for sea level. If the gauge was metric it might be in kilopascals (kPa) and the sea level idle vacuum would be about -61 kPa. -50 kPa would be about 14.7 in hg vacuum which wouldn't be too far off for somewhere above 5000 ft.

 

[trevnasty]

my guage read's vac in cm-hg goes all the way from 5 to 75 cm-hg the brand is spw the boost gague read's in bar's if that makes a diff?

 

[steve]

my guage read's vac in cm-hg goes all the way from 5 to 75 cm-hg the brand is spw the boost gague read's in bar's if that makes a diff?

See the conversion links above. Use them to convert.

 

[trevnasty]

i dont see a cm-hg converson to psi but i could just be special

 

[gsxtasy]

i dont see a cm-hg converson to psi but i could just be special

Because you're trying to convert cm to inches. 45 cm-hg = 17.7 in-hg, which is pretty close to normal.

 

[trevnasty]

thanks every one!!!!!!!!!

 

[steve]

i dont see a cm-hg converson to psi but i could just be special

In the link I posted it's the second one under Mercury.

 

[crimsondragon]

You can't pump off more than 1 atm (1.01 bar) until you reach 0 and can't go any lower. On planets with atmospheres the average pressure will differ from ours. So on Saturn it would be something like 1.39 bar and on Mars something like 0.00675 bar.

Interesting. That must be why they only make boost/vac gauges read -30 inHg. However, our barometric pressure differs daily. Could that somewhat explain why on some days my vac reads -20 inHg and other days it's 16?