BrownBoy

iTrader: (10)

Hey guys,

This doesn't have to particularly be on an LS1, but any idea where I could find out the average suction pressure generated by automotive engines? I'm trying to find out the pressure of the air entering the intake manifold. I assume it would be a function of the engine's displacement and RPM but I can't find much by searching online.

Any help would be greatly appreciated, thanks!

99ws6ls1

a vacuum gauge...

BrownBoy

iTrader: (10)

Great idea! Unfortunately, I don't have access to a running vehicle who's owner is willing to let me poke a hole in their manifold for a test.

bluess57

For an LS1 you can use EFILive/HPTuners and read the MAP (Manifold Air Pressure) value

BrownBoy

iTrader: (10)

Do you know anywhere these graphs might be available or anyone who would have these graphs for me to look at?

joecar

At idle, MAP is 35kPa (with stock cam).
At WOT, MAP is 100kPa.

MAP is a function of throttle blade angle and the engines compression ratio/ability.

LS1-450

iTrader: (33)

Don't know where there are charts, but, can tell you that @ idle the LS 5.7L MAP is anywhere from 20-60 kPa (near 40 kPa avg.) vacuum up to 92-105 kPa @ WOT. This is dependent upon VE, which is based on several variables.


Just that Joecar had posted when mine displayed. So, mine is redundant.

BrownBoy

iTrader: (10)

Thanks for that information guys, it's much appreciated!

If anyone else has some input and/or graphs, that would help me out a LOT!

ZeeOSix

If you're working on a specific LSx engine and want to check its "vacuum heath", then just hook a vacuum gauge up to the high vacuum port that the PCV line connects to (located just behind the throttle body on passenger's side).

ZeeOSix

Your numbers must be absolute pressure ... if so, then 40 kPa is more vacuum than 105 kPa. It's all in the terminology.

JS01

iTrader: (10)

The readings can vary greatly depending on what the weather is like that day, altitude and how restrictive the intake tract is. A multitude of things influence what the baro is inside an intake. Ideally you would want the 'vacuum' to equal '0' or be equivalent to the atmosphere at WOT (on a naturally aspirated engine at least). At part throttle/low load anywhere from 30-70kPa would seem fairly "normal" for these engines in my experience.

LS1-450

iTrader: (33)

No ****. That's why I went back & was removing the word vacuum from the post. Had incorrectly stated it twice. Was distracted while reviewing the post when I saw that joecar had posted. Typed the comment stating the redundant post & forgot that one. Knew that someone would waist time pickin' @ it.

ZeeOSix

Oh well ... that's what being technical is all about.