My truck just doesn't quite have the torque I'd expect it to. And now I've got my sights set on the exhaust system. The truck came with no cats and only a rusty old glasspack, which I'm already inclined to replace because I can't stand the racket it makes. Just wondering if I'll regain some torque as well.

 

a glass pack will kill hp and torque even tho you can see threw it it is one one of the most restricktive mufflers you can get

 

How can a glasspack be restrictive?

 

when you look threw a g-pack you will see lil tabs all around that stick out into the way off air flow ,these lil tabs create a sonic buble(makes the craking sound at tail pipe)that takes more power to push threw the rest of the exuast. an old man told me this about 17 years ago when i finaly listened to him i went 3 tenths faster at the drags.

 

Hmm, my glasspack doesn't have anytabs in it, instead it had bevealed oval shaped holes.

 

im a lil old school and never seen any like that. what kind are they?

 

Cherry Bomb 30"

 

Heres a link to pics of the inside of one. http://i188.photobucket.com/albums/z...cutaway_lg.jpg
http://i188.photobucket.com/albums/z...-glasspack.jpg

 

looks like the first link is the same as the ones im thinkin about

 

So, how are they restrictive if they are a straight shot?

 

I was waiting to see how you guys handled this post. I don't know how old you guys are but these things have been around for years. Back if the fifties we use to run stock flatheads at Morrow Field in Colton California. They watched you pretty close for cheating and the car had to be completely stock, but you could have dual pipes on it. I use to put the glasspacks on backwards and gained more than one second in et on an average. I was never caught cheating.

 

thats cool... how did the glasspacks sound reversed? i would think more like straight pipes... taking away some of the artificial crackle.

 

The new glasspacks sound the same no matter which direction. The cherry bomb I put on my truck didn't have a flow direction arrow.

 

The newer glasspacks are probably designed like the ones in photo 2 above. Those look like they wouldn't have a polarity. They also look like they wouldn't have the internal turbulence that the older ones had and might be more efficient. The old ones had what looks like louvers inside. These louvers were open to the front of the muffler and created the turbulence that causes the back pressure and quited the exhaust. This turbulence is probably what causes the loss of power that the guys are talking about. And yes the old glasspacks were louder when the were mounted in the wrong direction.

 

it's not a true straight shot when the area is reduced - air flow is changed quite a bit but I'm not willing to say thats worse than a typical performance muffler.