What size pipes to use?

I have a ‘64 Electra with a factory 425 (bored 0.60) with factory dual quads. what would you used for exhaust pipes? I already have a stainless dual in dual out muffler that I will be using.

 

What size is the inlet and outlet on the muffler you already have?

 

Hi,

Anything from 2-1/4" to 3" all depends upon space and appearance your after.

I'm running 2-1/2" on a 65 401 with Dual Quads, through Gran Sport manifolds. In my 65 Skylark.

Regards,

 

yeah, 2-1/2'' will give it the "not factory, but still decent-look"
3" or more is overkill

 

It doesn’t need 3” for sure. 2 1/4” or 2 1/2” will be plenty-I doubt you’ll be spinning it to the rpm that would be hurt by 2 1/4”.
Patrick

 

If I go larger than 2 1/2 I’m told I will lose out on bottom end torque, is that true?

 

Not enough you’d feel it, but you’d have exhaust that sounds like a drain pipe on a car that shouldn’t. It’ll sound like these clowns that put Floorblasters on a Titan with a stock engine.
Patrick

 

So single back to the muffler, then split at the muffler? I'd go with 2.5" from collector to the muffler, then 2.25 out the back.
I'm usually looking at stock applications on mine-If I were looking at duals for the Electra I might buy a system for the 65 Riviera and see if I could fit it.
I tried buying an A body TA exhaust and fitting to a Centurion and had mixed results.

 

The first generation Riv has an X-frame and would be an entirely different system. The Nailhead exhaust manifold has a 2" outlet and is the first restriction in the system. That should be increased with headers or porting before going to a larger exhaust pipe (IMHO). A 2.125" pipe would have 2" inside diameter and be no more restrictive then the manifold if it were mandrel bent. Each cylinder pulse cools and contracts as it moves through the exhaust. This effectively pulls or scavenges the pulse behind it as does. Increasing the pipe size slows the pulses in the tube. Too large a tube and the pulse velocity at the end of the tailpipe is not enough to effectively scavenge the pulses behind it. I'm sure Mr 62 Wildcat, as a result of his specialty muffler shop, would be able to educate us better.

I know it is best to give the exhaust more area where it is hot (headers), trade, line up and equalize the the pulses as best you can through an X or H pipe, then reduce to a smaller pipe that scavenges well for the size of the engine and HP capacity. You people must be tired of hearing about our Mustang by now, but it makes over 740 HP at the rear wheels using a 1 7/8" header to a 3" collector, to high flow Cats, to a 3" X pipe, to a 2.5" step down for a 2.5" cat-back and 2.5" tailpipes after another X pipe. Big pipes are not necessarily better.

Cheryl

 

64 Electra has an X frame.

 

Oops - I was looking at the 66 Manual thinking the 64 Electra's were the same.

 

2.5” might give better sound. 2” just looks so small nowadays.