Originally Posted by McFly

Great post, well said, and good info. I'm listening.No, it's making 210hp with 2.7psi of boost. It's been made clear. listen/read.I'm sorry FCDAIR, but you also need to sit back, listen/read, and learn. You've made too many mistakes on this thread, an you're just making it worse.

FACT: 14.5 is 1 bar. Look it up:
Online Conversion - Pressure Conversion

If you think that conversion site is wrong, good luck.

Absolute pressure is absolute, just like atmosphere is 14.7psi. So, absolute doesn't take into account what atmosphere is, the 14.7psi. Same thing you were going back and forth with Fleshbox about, absence of pressure is what vacuum is, vacuum is not absence of pressure.

Relative pressure, has to be "relative" to something, and you relate it to what atmosphere is. "How much over atmosphere are we talking?" Atmosphere is 14.7, and if absolute is 17.4psi, then relative is 2.7psi. Relative pressure is "what boost a car is running." In this case, from what we are hearing it's either 2.7psi (from what Jalmir said), or it's ~11psi (reading of ~.8bar, from what KSpec said), but definitely not 17psi.

Now, lets get down to figuring out what KSpec is saying and Jalmir are saying.

First, KSpec says:
"Stock boost is 0.8bar.

It peaks (jumps) to 1.0 or even 1.2 but for a slight second."

Hmm, it "peaks" to 1.2bar for a split second. That's interesting.

Now, lets look at the graph of what Jalmir posted:


Now, pay close attention to that graph. Not the big numbers in the right column, but the small numbers indicating min and max. The min and max, are the readings of the minimum read, and the maximum read. Hmm. Lets see, the maximum "Manifold Absolute Pressure" is 1.2bar. That means it may have spike to that, or it may have held at that... Looking at the graph, it looks like it spiked to that, 1.2bar. That's interesting... Didn't KSpec say that stock peaks to 1.2 for a slight second?

Sounds, like they are saying the same thing.

Go back to the "Manifold Absolute Pressure Graph," do you see where there is a plateau and then there is a bit of a spike. Would you say that the plateau is right at about .8 bar if the peak of the spike is 1.2bar? I would. Again, same thing that KSpec is saying: stock is .8 bar, and spikes to at most 1.2 bar.

Wait, we are talking absolute here, not relative. Relative pressure is "what boost are you running?"

Converting .8 bar and 1.2bar to psi, gives 11.6psi (.8*14.5) and 17.4psi (1.2*14.5) respectively. Again, that's absolute. So, lets convert to relative, by subtracting 14.7psi. 11.6psi -14.7psi = -3.1psi (vacuum), and 17.4psi-14.7psi = 2.7psi (boost). So, it's going from vacuum at -3.1psi, to boost at 2.7psi. No, it is not unheard of to go from vacuum to boost, happens all the time with turbos (ever looked at one of those factory dials that have a + and -)... sadly it even happens under boost. Pretty low boost apparently.

And there we have it people. Stock boost at the manifold is under vacuum at times, and then at most goes to 2.7psi.

But wait, that's not what we wanted to hear. We wanted to know how much boost the turbo is pushing out! AHAH!!! We want "Turbo Charger Boost" pressure. Boost [pressure] at the Turbo, not Boost [pressure] at the Manifold. The graph shows 1bar to 1.5bar. Obviously the 1bar is atmosphere, aka no boost. The 1.5bar is full boost... converting to psi gives 21.75psi(1.5*14.5) which is in absolute pressure. We then have to convert to relative pressure, subtracting 14.7psi, gives 7.05psi.

And there we have it. The Turbo is putting out 7psi stock at it's highest spike/peak, while the manifold is seeing 2.7psi at the highest spike/peak.


I hope I closed the book on the subject.