Kpa= ?

[06balt ss/sc s2]

Ok here is my first question.
I have been doing a bunch of reading on the cobalt forum about making adjustments as far as when PE kicks in. In relation to kpa (as listed in hpt). I read that 100kpa = 0 atmospheric pressure. 0 boost, 0 vac. And to set your PE MAP Enable to 115 kpa, so PE kicks in at a low boost point.
But when I get on a conversion table I get this, 100 kilopascal = 0.986 923 169 31 atmosphere [standard]. Also when I type in 100kpa and what it equals in psi it comes up 100 kilopascal = 14.503 773 801 pound/square inch.
Now currently my PE Enable MAP is set to 55kpa which in atmospheric pressure, 55 kilopascal = 0.542 807 743 12 atmosphere [standard], Inch of mercury 55 kilopascal = 16.241 490 689 inch of mercury [0 °C] and psi 55 kilopascal = 7.977 075 590 4 pound/square inch.
So my question is can I set my PE Enable MAP to 115 kpa or is that wrong. And what would be a good PE Enable Map setting other than what it is set at now which is the stage 2 setting.
Man Im confused, should have paid more attention in math class 25 yrs ago

[dont_blink]

You're looking at it all wrong. In engine terms, anything under about 107kPa at sea level is vaccum. This also happens to be about 14.7 psi at sea level or 1 atm (atmosphere). So setting it to 55kPa would mean that at about 10inHg or NEGATIVE 7 lbs of boost your PE kicks in. Most of us set it to around 5psi or 143kPa.

Remeber, in most applications requiring excess pressure, you must measure atmospheric pressure against incoming pressure. In a car, your MAP sensor is going to read atmospheric PLUS pressure. This is called actual or manifold psi expressed as psia. At 15.7psi on your MAP sensor though, you are only reading 1psi of boost. This is call gauge pressure, expressed as psig.

None of this would have come up in high school math though.

[06balt ss/sc s2]

AHHHHH. Ok I was just looking back at the tread on the balt forum and tring to figure this all out. Here is the thread, http://www.cobaltss.net/forums/showthread.php?t=64713
Not sure if Im allowed to post another forum, but anyhow.
Now what your saying makes sence. Thanks for the quick response.

[06balt ss/sc s2]

Oh now Im at about 600ft above sea level, and I was just talking to my friend who has the HPT and we were thinking of setting the kpa to about 120-125.
I know the gm stage 2 base tune runs pig rich and thus far we have not seen any kr and have bumped timing up about 3*. I am getting on the dyno next month to do some tuning along with a wide band to dial in the wot fueling.

[dont_blink]

Do yourself a favor and lean out the tune or clear out the cat before you have a catastrophic failure.

[06balt ss/sc s2]

I dont have a cat, and the COT has been turned off. My buddy and I did some tweeking this afternoon. Upped the kpa to 125, enrichment rate to 1.30. Were gonna do some more loging tomorrow, we also figured out how to add some more PID's so we want to see a little more info before we make anymore changes.
I do have another question though, under AFR-Stoich, its showing 14.69971. Is there a reason it not a solid 14.7? And can/should it changed to 14.7?

[dont_blink]

I dont have a cat, and the COT has been turned off. My buddy and I did some tweeking this afternoon. Upped the kpa to 125, enrichment rate to 1.30. Were gonna do some more loging tomorrow, we also figured out how to add some more PID's so we want to see a little more info before we make anymore changes.
I do have another question though, under AFR-Stoich, its showing 14.69971. Is there a reason it not a solid 14.7? And can/should it changed to 14.7?

I'd go lower on the enrichment, like 1.24 honestly.

[06balt ss/sc s2]

Well that would lean out the tune, and right now I have a thread on here about a lot of kr. I belive its cause the afr is lean.

[dont_blink]

Nah. If you're doing it right you can run 19 degrees advanced at 11.8:1 AFR with no KR. Check your VE tables ;-)