andy-gts

I received my level 2 devek headers and 3 inch exhaust with crossover and catsjune 23 2007, ordered may or june, can't remember. But super quality work. I am waiting on some cams (B1) from devek but they are hard to arouse on email and I know Marc has alot of Irons in the fire . sound like a great guy and man I wish I had his energy.
Just my 0.02
andy

Mike Simard

The collector length is the secondary pipe length and it's length, between the primaries and crossover, is subject to harmonics that favor certain rpm ranges. That secondary pipe length would almost certainly like to be a bit longer than the collector on the header. Using Pipemax to calculate secondary pipe length for a big stroker gives and ideal of 16 inches which would put a crossover about a foot back from the header flange.

About the crossover being the termination of the secondary pipe, ideally it would terminate into a large chamber before rejoining into 2 pipes going to the mufflers, I'm not sure if a small crossover behaves differently than a large chamber or open air but IMHO it can be considered the termination point.

Vilhuer

So its better to have headers-cats-X than headers-X-cats. IIRR Devek had headers-cats-X version on display during some meet they held.

drnick

mike, thanks for the explanation. what is the effect of reducing engine swept volume in those equations ie going from a 6+ litre stroker back to a 5.0 - 5.4 litre engine? i suppose the consideration is perhaps slightly moot for me as i was intending to install the X crossover as far forward as is easily practicable - predominantly for the sound. i have formed the impression that the x further forward produces more of the 'ripping silk' sound rather than the ww2 bomber sound.. any one else think this?

Tass 928

I started on my exhaust system today. Recap...I have MSDS headers on my 79' neverbeenonthetrack track car. I started with a generic x-pipe kit from jegs. I have chopped and welded it into this, a piece that will fit in the cat-space and then narrow the two pipes together so they fit through the floor tunnel.

Next up, the front sections connecting to the headers.

Note..these are 3" pipes.

Tass 928

[QUOTE=Sterling;4676303]The angles are too extreme for efficient airflow. The generic X kits from jegs are designed with the domestic cars undercarriage in mind and are a compromise for fitment and performance.

Sterling RE your pipe, is the cross sectional area of that narrow center section equal to the two 3" round pipes? or is that not required?
That does look like a better flowing pipe than my plan.This idea will get better as I move forward. A lot of the inlet angle will be chopped off when I make the header connector pcs. Bad illustration below:

Tass 928

I don't think mine would be equal to the two 3" pipes either. Just wondering if that would be the ideal situation. Maybe anything less would be a restriction?

Tass 928

Added the pipes at the header end. Now we have a pause in the action while I locate some 3" , 3 bolt flanges to weld on.

Tass 928

Pipes cut, header flanges located and tacked. I'll bring it home for a test fit before welding them up.

SMTCapeCod

Very purty, wish we'd had a chance to tackle that update on mine!
My thoughts were less crafty though, a manaflow muffler with an internal 'X' and using v-band clamps so I could use the bends in the OEM midpipe to align either with the stock cats or with the modified 'x' configuration. Would've been frankenpipe by comparison, I suppose.

Tass 928

I'm not done with you yet If you make it to our event on the 3rd you can explain in person what you are looking for.

Airflite40

Hey Dave, IIRC I sold you my old MSDS headers right???

Tass 928

Nope. Had them ceramic coated and installed them.

Tass 928

Well, I tacked the flanges on upside down so I had to cut and retack when I got home and did the test fit. Here is where we are now....

RicerSchnitzzle

Excellent! Hope you don't mind me stealing pics of your progress to give my exhuast guy.

I wish I was that talented.