LS4 Performance Grand Prix GXP | Monte Carlo SS | Impala SS | LaCrosse Super

what is this?

Thread Tools
 
Search this Thread
 
Old Mar 11, 2011 | 02:03 PM
  #1  
f3racer's Avatar
Thread Starter
Banned
 
Joined: Feb 2011
Posts: 122
Likes: 0
From: lebanon, mo
Default what is this?

hose coming from front valve cover to throttle body

Reply
Old Mar 11, 2011 | 02:06 PM
  #2  
2005gxp's Avatar
TECH Resident
 
Joined: May 2010
Posts: 803
Likes: 0
From: Ontario, Canada
Default

vaccuum vent. i dont have my tube on there anymore. no issues.
Reply
Old Mar 11, 2011 | 03:30 PM
  #3  
DavidGXP's Avatar
12 Second Club
iTrader: (14)
 
Joined: Jun 2007
Posts: 2,563
Likes: 0
From: Renton, WA
Default

It's your clean air, positive crankcase vent.
It is need.
Reply
Old Mar 11, 2011 | 03:47 PM
  #4  
f3racer's Avatar
Thread Starter
Banned
 
Joined: Feb 2011
Posts: 122
Likes: 0
From: lebanon, mo
Default

i replaced the tube with a small filter.
Reply
Old Mar 11, 2011 | 06:07 PM
  #5  
DavidGXP's Avatar
12 Second Club
iTrader: (14)
 
Joined: Jun 2007
Posts: 2,563
Likes: 0
From: Renton, WA
Default

That will work
Reply
Old Mar 11, 2011 | 06:11 PM
  #6  
hazards280's Avatar
TECH Regular
 
Joined: Aug 2010
Posts: 446
Likes: 0
From: Midland MI
Default

Originally Posted by DavidGXP
It's your clean air, positive crankcase vent.
It is need.
That's what I thought.
Reply
Old Mar 11, 2011 | 07:22 PM
  #7  
DavidGXP's Avatar
12 Second Club
iTrader: (14)
 
Joined: Jun 2007
Posts: 2,563
Likes: 0
From: Renton, WA
Default

Now get a catch can for the dirty air side.

The stock system allows a bunch of oil to enter into the intake manifold. This effects airflow and pollutes the air/fuel mixture wich can cause detonation. The back sides of your intake valves will become caked with collegiated oil. (my valves and piston tops where)
This is a very serious problem, and combined with DOD activation, it is easy to burn thru oil rather quickly. Definitely not good..
Reply
Old Mar 13, 2011 | 08:18 PM
  #8  
nmp0098's Avatar
TECH Regular
 
Joined: Nov 2009
Posts: 446
Likes: 0
From: Farmington Hills, MI
Default

Originally Posted by 2005gxp
vaccuum vent. i dont have my tube on there anymore. no issues.
Maybe a turbo car is different, but when I ran both the clean and dirty side into the manifold under vacuum I saw a nasty buildup of condensation in my valve covers... not good.

Originally Posted by f3racer
i replaced the tube with a small filter.
I wouldn't recommend that... you are creating a vacuum leak. I screwed this up a while ago, because the PCV system is different on newer cars and I didn't realize it at first.

There is a clean side and dirty side to the system. At WOT, both will flow into the manifold. If you do a lot of high RPM stuff, like land speed or circle track racing, you'll actually want to put a catch can on BOTH sides!

At part throttle, air flows through the MAF (and is therefore metered) and into the clean side, through the crank case, and out the dirty side. This cycles the all of the nasty blow-by back into the combustion chamber and out of the exhaust. There is a lot of stuff you don't want in there, but iirc sulfur dioxide is the biggie. It's acidic, and will rot the engine out from the inside. The metered air that flows through the clean side mixes with the blow-by, but the blow-by isn't combustable so it doesn't matter from a fueling perspective.

So, you want to leave that tube hooked up between the MAF and the throttle, and the dirty side should always go directly into the manifold. Using breathers not only messes with emissions, but also shortens the life of your engine.
Reply
LS1 Tech Stories

The Best V8 Stories One Small Block at Time

story-0

Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

 Verdad Gallardo
story-1

6 Common C5 Corvette Failures and What's Involved In Repairing Them

 Pouria Savadkouei
story-2

Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

 Verdad Gallardo
story-3

Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

 Pouria Savadkouei
story-4

Top 10 Most Powerful Chevy Trucks Ever Made!

 
story-5

Hennessey's New Supercharged Silverado ZR2 Has 700 HP

 Verdad Gallardo
story-6

Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

 Verdad Gallardo
story-7

Awesome K5 Blazer Restomod Comes With C7 Corvette Power

 Verdad Gallardo
story-8

10 Camaros You Should Never Buy

 
story-9

10 LS Engine Myths That Refuse to Die

 Verdad Gallardo
Old Mar 13, 2011 | 10:41 PM
  #9  
DavidGXP's Avatar
12 Second Club
iTrader: (14)
 
Joined: Jun 2007
Posts: 2,563
Likes: 0
From: Renton, WA
Default

Originally Posted by nmp0098
Maybe a turbo car is different, but when I ran both the clean and dirty side into the manifold under vacuum I saw a nasty buildup of condensation in my valve covers... not good.



I wouldn't recommend that... you are creating a vacuum leak. I screwed this up a while ago, because the PCV system is different on newer cars and I didn't realize it at first.

There is a clean side and dirty side to the system. At WOT, both will flow into the manifold. If you do a lot of high RPM stuff, like land speed or circle track racing, you'll actually want to put a catch can on BOTH sides!

At part throttle, air flows through the MAF (and is therefore metered) and into the clean side, through the crank case, and out the dirty side. This cycles the all of the nasty blow-by back into the combustion chamber and out of the exhaust. There is a lot of stuff you don't want in there, but iirc sulfur dioxide is the biggie. It's acidic, and will rot the engine out from the inside. The metered air that flows through the clean side mixes with the blow-by, but the blow-by isn't combustable so it doesn't matter from a fueling perspective.

So, you want to leave that tube hooked up between the MAF and the throttle, and the dirty side should always go directly into the manifold. Using breathers not only messes with emissions, but also shortens the life of your engine.
Great post/response as I was just thinking about all of this stuff today while driving around. (4.00 per gallon)

The clean side air should be left intact.
Reply




All times are GMT -5. The time now is 01:10 AM.

story-0
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-1
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-2
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-3
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-4
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-5
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE
story-6
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.

By Verdad Gallardo | 2026-03-23 18:53:41


VIEW MORE
story-7
Awesome K5 Blazer Restomod Comes With C7 Corvette Power

Slideshow: A heavily reworked 1972 K5 Blazer swaps its off-road roots for a low-slung street-focused build with modern V8 power.

By Verdad Gallardo | 2026-03-09 18:08:45


VIEW MORE
story-8
10 Camaros You Should Never Buy

Slideshow: There are thousands of used Camaros on the market but we think you should avoid these 10

By | 2026-02-17 17:09:30


VIEW MORE
story-9
10 LS Engine Myths That Refuse to Die

Slideshows: Which one of these myths do you believe?

By Verdad Gallardo | 2026-01-28 18:10:11


VIEW MORE