flynhi

I'm trying to tone down my Edelbrock RPMs. They're great mufflers - high flow, stainless but - a bit loud. I've thought about using 32" long, 4" diam glasspacks between my x crossover and the mufflers. Zwede has tried this with some success. Anyone else tried it? If so, what did you use?

Vetterodder

I think a crossover, or just replacing the mufflers, would be a better choice. A crossover would probably lower the sound levels and also improve low end power a little. Straight thru glass packs are much more restrictive than even stock mufflers. Using them in addition to even the best flowing mufflers will result in something worse than stock. Dynomax and others make mufflers that flow about as well as much louder ones but are only slightly louder than stock.

Shock

I have used the Borla XR1 short glasspak for this. It is about 16" long and does a decent job of absorbing resonance. Makes the car overall quieter and the exhaust note is more mellow. There is very little backpressure in an XR1 so there is no loss of flow.

Beware, that they are not that cheap. Best price I could find is around $100 each.

Mike

flynhi

Vetterodder,
I was thinking of straight flow thrus with perforated cores - similar to the dual path perforated core inside the Edelbrock RPMS. Several sources I have read indicate that the typical glasspack (cherry bomb, etc) has a louvered core which has high backpressure as you mentioned.
The ones I am considering are perforated core like the Walker Magnum glasspack or the Thrush Glasspack.
I'll check out the Borla mentioned above.

Ganey

Agree w/ Vetterodder. Better muf. rec.! You would be adding unnecessary wt.!

:cool:

PS Some glasspacks flow better reversed.

BeaterShark

I run 2 30" glasspacks with a 2 1/2" perferated core tube. It is not quiet, but definately quieter than open headers. You really have to watch out for the core tube sizes as I've seen 2 1/2" mufflers with a 2 1/4" core tube.

Please explain or show where this has been proven.

I don't see how the perferated core type would be much more restrictive than straight pipes. The louvered core type are more restrictive, but if sized and installed properly, I don't think they are more restrictive than a stock muffler.

I'm pretty sure that the Borla and Dynomax race mufflers are stright through glass packs. :bb

yellow 72

:iagree: Plus if you do some homework you will find a lot of the turbo style oval mufflers use perferated cores of some type, the larger area for damping material is what makes them quieter...

flynhi

Beater,
What brand of glasspacks are you runnin?

BeaterShark

I think they are from a company called HeartThrob exhaust. I cannot find any info on them so I'm not sure they are still in business. They had both louvered core (quieter) and the perferated core in just about any imaginable size up to 3" core tubes.

I also remember reading from the Ford Cobra guys that some of them are running some from J. C. Whitney. They too offer up to 3" core glasspacks. I think they are the perferated core type, but I'm not certain about it.