Muffler size ?

[FUNFER2]

I think with big blocks, 3.5" may help or, not at all ?

Although, I've seen a few dyno sheets that show with 2" primaries, 3" collectors and 3.5" mufflers, really help out so, I'm sure I'll go that route.

Now I have to make up my mind, on either mild steel and have them ceramic coated or stainless. I have a industrial buffer machine that I could polish them myself but, that will take a lot of time. If I could find a business and buy the pipes already polished, that would save a lot of time but, even that would be expensive. The advantage to SS is, longevity versus the ceramic lasting only a hand full of years, before you can't polish them out anymore, like what's happened to mine.

Thank you for the site link.

[Ant]

Kevin,

I think with 3.5" OD that gives a good amount of size, and you are probably right your Big block has substantial horsepower and may benefit from large mufflers. My understanding was with race cars they went big in the whole system depending on the rpms used!

Mild steel is good when ceramic coated and the advantage of cooler areas surrounding the where the exhaust goes, my pipes rusted bad after the dyno run but are now coated so should be ok for a few years - might see me out who knows!

[undy]

Kev, 3" is all you need.

Dave

[Rare Iron]

Read this from Ron Nichols - it's down in the thread a little on the first page: Howe Racing Mufflers

Personally, I don't think many Cobra owners would install mufflers with a 4.5" body diameter. According to Dynomax & their flow criteria, a straight-through Ultra Flow muffler with a 3" core will flow over 2200 CFM, which translates into over 1800 loss-free horsepower with a dual exhaust. Here's their formula:

How to determine necessary exhaust flow:
* Engine HP x 2.2 = loss free airflow capacity needed for a muffler used in a single system.
* For a dual system divide the single system number by 2 to determine the loss free airflow capacity needed for each muffler.

EXAMPLE:
* 300 HP x 2.2 = 660 SCFM single or 330 SCFM dual.