I hope this isn't a stupid question, but is there a formula to convert a kPa reading to #s of boost?

 

6.9 kPa is about 1lbs of boost

 

Roughly 6.9kPa = 1psi

 

Thanks. I was logging a boosted car today with a 2 bar map and no boost gauge. Was pretty sure I could use the map reaading to figure out the boost.

 

This will probably help out alot for your conversions.

http://www.ilpi.com/msds/ref/pressureunits.html

 

I just took map - 101 / 6.9 and that gets me pretty close.

 

I've always thought that 6.8 gives you more realistic numbers. Don't know why people are rounding up to 6.9.

Jim

 

actual equation is 6.8947625. Difference between .8 and .9 is right around .001 PSI.

 

generally speaking most map sensors will read 100kpa as 1 bar atmos, or 0psi boost.

0 kpa.....0 bar.....-14.7 psi ( most guages read vac in inches of Hg/mercury though )
100kpa...1 bar.....0 psi atmospheirc pressure
200kpa...2 bar.....14.7 psi boost
300kpa...3 bar......29.4 psi boost

 

I've always been an out of the box thinker, the way I always convert if I need an exact number is like this:

100 KPA = standard pressure

140 KPA = 1.40 * 14.7 = 20.58 PSI

50 KPA = 0.50 * 14.7 = -7.35 PSI = 14.7" vacuum.

 

Good point. I always thought it was closer to 6.8.

Thanks,

Jim

 

incorrect. 50kpa is generally in vacuum, which will not be measured as positive pressure in psi.

by your reasoning, 100kpa as standard pressure is meaningless. What is standard pressure ???????

100kpa is atmospheric pressure, which you can take as 14.7psi if you want, but generally its 0psi guage.

 

I dont think what you said is right.................

UnitEquivalent measurements, commentsPounds per square inch
(psi, PSI, lb/in2, lb/sq in)Commonly used in the U.S., but not elsewhere. Normal atmospheric pressure is 14.7 psi, which means that a column of air one square inch in area rising from the Earth's atmosphere to space weighs 14.7 pounds.Atmosphere
(atm)Normal atmospheric pressure is defined as 1 atmosphere. 1 atm = 14.6956 psi = 760 torr.Torr
(torr)Based on the original Torricelli barometer design, one atmosphere of pressure will force the column of mercury (Hg) in a mercury barometer to a height of 760 millimeters. A pressure that causes the Hg column to rise 1 millimeter is called a torr (you may still see the term 1 mm Hg used; this has been replaced by the torr). 1 atm = 760 torr = 14.7 psi.Bar
(bar)The bar nearly identical to the atmosphere unit. One bar = 750.062 torr = 0.9869 atm = 100,000 Pa.Millibar
(mb or mbar)There are 1,000 millibar in one bar. This unit is used by meteorologists who find it easier to refer to atmospheric pressures without using decimals. One millibar = 0.001 bar = 0.750 torr = 100 Pa.Pascal
(Pa)1 pascal = a force of 1 Newton per square meter (1 Newton = the force required to accelerate 1 kilogram one meter per second per second = 1 kg.m/s2; this is actually quite logical for physicists and engineers, honest). 1 pascal = 10 dyne/cm2 = 0.01 mbar. 1 atm = 101,325 Pascals = 760 mm Hg = 760 torr = 14.7 psi.Kilopascal
(kPa)The prefix "kilo" means "1,000", so one kilopascal = 1,000 Pa. Therefore, 101.325 kPa = 1 atm = 760 torr and 100 kPa = 1 bar = 750 torr.Megapascal
(MPa)The prefix "mega" means "1,000,000", so one megapascal = 1,000 kPa = 1,000,000 Pa = 9.869 atm = 145 psi.Gigapascal
(GPa)The prefix "giga" means "1,000,000,000", so one gigapascal = 1,000 MPa = 1,000,000 kPa = 1,000,000,000 Pa = 9,870 atm = 10,000 bar. Pressures of several gigapascals can convert graphite to diamond or make hydrogen a metallic conductor! Such high pressures are rarely encountered in everyday life.

 

Actually he is pretty much correct.

Dave

 

Yes I did not know a 1 bar MAP is pretty much useless while logging the MAP on HP tuners. I was informed you would need a 2 bar or higher to log the MAP accurately...

 

Here is a chart.

 

i'm learning here about this kPa stuff, so any help is appreciated!...

so i have the stock map sensor right now, and at WOT it shoots right to 103 kPa via HP tuners. now 2 questions:

if the guage shoots right to 103 at WOT, that means that the system is making boost, right?

also, if i want to read more than 103 kPa, then i have to upgrade to a 2 bar map sensor right?

:edit:
can i just swap the sensors, or is there additional tuning needed?
(found the answer to this one..... need a new OS for that...)

thanks