Exhaust

Well it seems that the drone is a common problem which the standard rear

boxes deal with quite efficiently. I’m going to have to tackle this problem in

a slightly different way.

For now, I want to deal with an issue I have with the amount of un-even exhaust

soot between the tail pipes. The spun boxes from www.birchillsautomotive.com were

twin 2 ½” in and single 2 ½” out. I would have thought that inside the box would have been

a “Y” joiner to equally split the in coming exhaust gasses between the twin exits. The fact that

the tail pipes have different amounts of soot deposit would suggest something a bit weird with

the construction.

Time today for some surgery.

I don’t pretend to understand the science behind silencer construction, but this design

does leave me wondering why it has been made like this. Obviously there is no way

exhaust gasses could flow equally out of the 2 tailpipes.

I wonder if I’d bought the single centre in and twin out instead of single offset in / twin out

the construction would have been any different ? Overall the actual construction looks

quite robust (not withstanding the mild steel mig welds to tack the baffle plates to the outer

skins !....a bit naughty that ! )

Some cutting later:-

Some joiners to create at shallow “Y” piece.

I don’t think this will perfectly equal the exhaust flow into each tail pipe, but it should be a lot

better than before.

Some added packing, closure of the box, a bit of buffing and nearly good as new.

I wonder how the exhaust will sound now that there is no empty chamber in these ???

I really don’t think the drone is going to disappear though………

……some time later, boxes now fitted, been for a short drive, and first impression is good.

Drone is somewhat less than before although I’m not declaring this sorted just yet.

Thanks to Joe Ellis of BTB exhausts who first put me onto the idea of quarter wave pipes.

More inspiration from the Pontiac G*8 guys in US http://www.g8board.com/forums/showthread.php?p=757955#post757955

During fitting I checked that there is enough space above the boxes for a quarter

wave pipe and there is !......so this will be next…….or build the rest of pipework to

cats….can’t decide which just yet…….

Think it will be the quarter wave pipe as drone will always be there !

Using some cad confirms design and adjustable pipe length with a slider piece

for 3” fine adjustment.

Just need to find some time to stick this all together……….