Boost pressure

[telnut]

I have just been looking at the VFAQ about compressor comparsions and reading turbo maps. If I am understanding this correctly he says that I have to add 14.7 to my boost gauge to get total boost. I have Blitz dual sbc's installed on all of my DSM's (5 of them) all 1gs. Does this mean that when my EBC is reading 19 inches of boost that I am actually boosting 19+14.7=33.7 inches of boost? (YIKES!) If this is so than I have been miscalculating my boost pressure and not setting the EBC correctly. I have asked Blitz about this question and have not recieved any answers. I have only blown one engine and that was when my boost gauge hit 33 inches and crushed the piston lands, the waste gate hose came off during the run. My understanding is that when we talk about boost pressure we are talking about the pressure the gauge is reading not adding 14.7 to the reading, is this correct?

Telnut

 

[brute]

There are many opinions on this subject. Here's one:

Gauge Pressure measures the pressure above atmospheric, so a gauge pressure reading at atmospheric conditions will read zero. Boost gauges measure the manifold pressure relative to atmospheric pressure, and thus are measuring Gauge Pressure. For example, a reading of 12 psi on a boost gauge means that the air pressure in the manifold is 12 psi above atmospheric pressure. For a day at standard atmospheric conditions,

12 psig + 14.7 psia = 26.7 psi absolute pressure in the manifold

Remember, that's at sea level where the atmospheric pressure is 14.7. Here in Albuquerque, we're at about 5,000ft above sea level, and out atmospheric pressure is 12.08 or so.

 

[EclipseTrbo420A]

Set your boost according to your gauge, if its a standard PSI reading if not...

I think he may think you are reading in bar...where 1 bar = approx 14.4 PSI. understand that?

So what he may be saying is for every 1 BAR IS 14.4 so you know where you are at.

http://www.dsmtuners.com/forums/showthread.php?p=151063601

 

[telnut]

Then my understanding is correct. Boost pressure is what the ebc reads, not ebc reading + 14.7. For a minute I thought what I have understood for 30 years was wrong. BTW my ebc's reads in cm2hg so I have to convert to find psi, this kind of drive me nuts. But I taped a small conversion chart in the upper left corner of the windshield to help me convert. I wish Blitz would convert their meters to psi for us yanks. Thankyou for helping me clear up what I understood. My experience has been that even old dogs sometimes discover they have bad concepts! Thanks guys I think I am begining to somewhat understand this internet posting thing. The kid has been trying to get me to learn how to do this for a couple of years. I teach him cars and he teaches me internet, we both come out with something good.

Telnut
"Motor oil in my veins and nuts and bolts in my brain."

 

[EclipseTrbo420A]

Then my understanding is correct. Boost pressure is what the ebc reads, not ebc reading + 14.7. For a minute I thought what I have understood for 30 years was wrong. BTW my ebc's reads in cm2hg so I have to convert to find psi, this kind of drive me nuts. But I taped a small conversion chart in the upper left corner of the windshield to help me convert. I wish Blitz would convert their meters to psi for us yanks. Thankyou for helping me clear up what I understood. My experience has been that even old dogs sometimes discover they have bad concepts! Thanks guys I think I am begining to somewhat understand this internet posting thing. The kid has been trying to get me to learn how to do this for a couple of years. I teach him cars and he teaches me internet, we both come out with something good.

Telnut
"Motor oil in my veins and nuts and bolts in my brain."

Sounds like a good arrangement. Good luck.