Exhausting questions

[KevF]

Guys,
The exhaust on the Coronet seems to be a true dual steel system with a cherry bomb on each pipe (albeit badly welded). Looking to get this replaced early next year with a stainless system. Looking online there are lots of arguments for and against going 3 inch vs 2.5in, x pipe or h pipe without even going into choice of silencer.

With my 440, it’s got a purple cam with Holley double pumper carb but that’s all I know. I am thinking that, from the Hedman headers, going 2.5inch into a X pipe placed middle of the car with two Flowmaster 50’s finishing in straight cut tips.

Does this sound reasonable to those that have done theirs?

Also any recommendations for someone to do the work, preferably Norfolk/Suffolk way?

Cheers.

[Dave999]

i don't know the state of tune of your motor and i don't know V8s, (however i did a bit of research when i got my exhaust done)
but it sounds like a small - medium step up over standard better cam better carb
in which case a decent set of headers sized to be just a fraction bigger than the ports in your head and an exhaust sized on the collector flange size would do the job. provided the headers were made by a sensible manufacturer the collector size will be sensibly matched to the size of the tubes from each cylinder
if you plan a fire breathing high CR massive solid or roller cam motor in the future. then it wouldn't.

comes down to what your plan is

great big exhaust on a motor that doesn't need it tends to spoil the low end torque, drones, costs more, is hard to route, makes a right old racket, money spent to get off the mark slower than you did before, but a smidge more power at full throttle.


so in my mind if the headsman's end at 2.5 keep the rest 2.5 and merge it quite far back. keep in mind the trans and prop might have to come out at some point after the exhaust is built(flanged H pipe) and you don't want to melt your speedo drive and handbrake cables.

[lough3969]

I have HEdman headers into 2.5 x pipe and flow masters ending before the rear axle... on a 68 Dart with strong 360. It’s a great sound! BUT there are those that don’t like the drone from flowmasters on the motorway.... most of the haters also complain about lack of heating, power steering and electric windows though.... if your in that camp then check out Magnaflows, they are also straight through but have sound absorbing material in. Every car will be different but it sounds like a perfectly good set up.

[Dave81]

From all my research online.

2.5" is good upto circa 500-550hp. Over that you need the extra flow of 3".
X pipe and H pipe make around 1-3hp over true duals on a 400hp motor.

I'd guess your setup you will be in the 300hp range.

In reality you wont feel that difference, so for ease of access i would stay as true duals.

Up to you at the end of the day though.........3" will just be louder.

My 2.5" system with Flowmaster 40s dumping at the rear axle is loud.
I'd not want it any louder TBH on long drives (Pod and Back).

318 pushing out diddly Bananarama! by the way so power is not my issue at the mo.......

[Mossy68]

Same as Dave on my Coronet. Sounds lovely for a small block ( imo )