WHY DID GM put restrictive blocks in plenum???
Thread Starter
Burning Brakes
Joined: Jul 2003
Posts: 922
Likes: 1
From: Brisbane Queensland, Australia
WHY DID GM put restrictive blocks in plenum???
http://forums.corvetteforum.com/pho.../cat/500/page/1
'For some reason GM put restrictive "blocks" in front of the EGR passages and to the left and right of the throttle body openings. You can grind down the front blocks and you can radius the side areas for improved airflow'
I'm after a DEFINATIVE answer here guys'n'gals...It doesn't look like this was merely a machining ommission, so does anyone know WHY they deliberately put the 'ledges' in the floor behind TB?
Obviously it helps suck the EGR gases into engine better, so when one grinds out these ledges, does that mean EGR gas burging suffers?
I don't have a copy of TPI Hints so am unsure of any reasons they give...
'For some reason GM put restrictive "blocks" in front of the EGR passages and to the left and right of the throttle body openings. You can grind down the front blocks and you can radius the side areas for improved airflow'
I'm after a DEFINATIVE answer here guys'n'gals...It doesn't look like this was merely a machining ommission, so does anyone know WHY they deliberately put the 'ledges' in the floor behind TB?
Obviously it helps suck the EGR gases into engine better, so when one grinds out these ledges, does that mean EGR gas burging suffers?
I don't have a copy of TPI Hints so am unsure of any reasons they give...
Le Mans Master
Joined: Sep 2004
Posts: 6,019
Likes: 568
From: Conroe Texas
the story i heard many years ago was, those humps were put in to prevent vapor lock while gm was testing in the desert heat. i don't know if many of us drive too much in the desert, but i ground mine out years ago and doesn't seem to hurt emissions any.
Thread Starter
Burning Brakes
Joined: Jul 2003
Posts: 922
Likes: 1
From: Brisbane Queensland, Australia
Originally Posted by Sleazy Rider
the story i heard many years ago was, those humps were put in to prevent vapor lock while gm was testing in the desert heat. i don't know if many of us drive too much in the desert, but i ground mine out years ago and doesn't seem to hurt emissions any.
Safety Car
Joined: May 1999
Posts: 3,651
Likes: 5
From: Atlantis
Cruise-In I Veteran
They create a low pressure area directly above the EGR ports.
The airflow over them adheres to Bernoulli's Principle, speeding up as it crosses the restrictions thereby augmenting the pressure that provides the motive force for EGR injection.
The airflow over them adheres to Bernoulli's Principle, speeding up as it crosses the restrictions thereby augmenting the pressure that provides the motive force for EGR injection.
Thread Starter
Burning Brakes
Joined: Jul 2003
Posts: 922
Likes: 1
From: Brisbane Queensland, Australia
Originally Posted by VetNutJim
They create a low pressure area directly above the EGR ports.
The airflow over them adheres to Bernoulli's Principle, speeding up as it crosses the restrictions thereby augmenting the pressure that provides the motive force for EGR injection.
The airflow over them adheres to Bernoulli's Principle, speeding up as it crosses the restrictions thereby augmenting the pressure that provides the motive force for EGR injection.
