Resonator fitting

_dwat_, Dec 14, 7:35pm
Ive been told i need to install a resonator on my austin 1300, just failed wof for being too loud.

Basicly the pipe from manifold is 1 1/4 then goes into 1 3/4 pipe with a muffer slapped in the middle.

My question is what size inlet outlet should i have on the resonator for when i cut out a piece of 1 3/4 pipe should i go for 2", same size or smaller!

mrfxit, Dec 14, 8:17pm
Smaller will maker it cackle on off throttle & tinny ON
Bigger will make it sound like a straw in a drain pipe
1 1/2slightly smaller then current.
Exhaust gas's contract as they cool & move along the pipe.
Reducing the pipe size helps to maintain an equal consistent back pressure

WHAT "exactly" will happen to the sound is anybodys guess until you start testing

chebry, Dec 15, 6:09am
BMC 1300s only had one muffler in the system and were never very quiet, are the decibel nazis picking on old cars now!

bellky, Dec 15, 6:44am
Same size.

mrfxit, Dec 15, 8:02am
Op's exhaust pipe would be something like 50% bigger then factory size.
Factory muffler was normally the best part of a 1m long

mrfxit, Dec 15, 8:10am
What type & design muffler are you currently running.
If it's a tube muffler (coby type) has it got an empty chamber inside 1 end or is it fully piped

mrfxit, Dec 15, 9:08am
To really understand the basics of a hot air exhaust system, 1st you need a basic understanding of thermodynamics

bellky, Dec 15, 10:00am
Oh right - seems like mostly Hot Air to me.

:)