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6.2 owners - Dual or Single Flapper


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Just curious if maybe it's a trim level thing?  I have an LT Trailboss 6.2 and only a single flapper.  I've heard many say they have 2?

 

Not really "important" per se, just curious if it was perhaps a lack of them in stock?  They wanted the higher trims to have more sound deadening?  

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The official reason from GM for the flapper is to increase back pressure to increase fuel mileage when in 4 cyl (14-18) or less than 8 cylinder mode.  Not saying anyone has to believe it, just sayin'.  

Edited by SILVER SLED
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19 hours ago, Rob Mugs said:

Just curious if maybe it's a trim level thing?  I have an LT Trailboss 6.2 and only a single flapper.  I've heard many say they have 2?

 

Not really "important" per se, just curious if it was perhaps a lack of them in stock?  They wanted the higher trims to have more sound deadening?  

What is a flapper? Thanks.

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1 hour ago, JohnH4260 said:

What is a flapper? Thanks.

Do you have a 6.2?  If so, hop under your truck.  Near the muffler, you will see a square bolt and spring. 

 

It closes off the exhaust at low rpm to reduce drone while cylinders are deactivated. 

 

So, it seems like it's completely random on if they got one or two

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49 minutes ago, Rob Mugs said:

Do you have a 6.2?  If so, hop under your truck.  Near the muffler, you will see a square bolt and spring. 

 

It closes off the exhaust at low rpm to reduce drone while cylinders are deactivated. 

 

So, it seems like it's completely random on if they got one or two

Ordered my Sierra Denali last week with the 6.2. I’ll have to check after it arrives in March. Thanks for the explanation.

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43 minutes ago, JohnH4260 said:

Ordered my Sierra Denali last week with the 6.2. I’ll have to check after it arrives in March. Thanks for the explanation.

Here's a better explanation.  Note at the 36 second mark.  Even when wide-open, it's still restricting the flow by maybe 30%

 

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