I sure as hell hope that the 180-degree crossover exhaust sounds good because it’s a lot work. Like everything else, there’s a learning curve. The first step was to mock the tubes that cross under the oil pan. The longest crossover tube sets the length of the other seven tubes so you want it to be as short as possible.
It looks like I’ll be able to get them all to be 38” long, but I still need to finish the #2 and #8 tubes on the right side. The pictures below show the left header. The two middle tubes (#3 and #5) cross under the oil pan and the front and rear tubes (#1 and #7, respectively) take a circuitous route before feeding the left merge collector. The merge collector is located where the stock transaxle adapter plate bracket is located. I will replace the stock bracket with a dog-bone bracket leaving that desirable space at the bottom open. A custom four-tube flange will be located under the middle of the oil pan allowing the left and right headers to be separated.
The plywood is the underside of the car, the blue tape on the plywood delineates the lower 2” x 2” chassis rail and the green tape delineates the upper rail. Each piece of yellow tape indicates two cuts and a weld.
The icengineworks blocks are extremely useful and I’ve learned a couple of tips:
Use a Sharpie to write the centerline radius (CLR) in the same location on every block before you start. This will save you a lot of time trying to read the molded print — or maybe I’m just old. This will also help prevent a different CLR being inadvertently inserted into a bend.
Always have a J bend and/or a U bend of every CLR on hand. It’s a lot easier to hold various CLR sections up to see what fits best vs. snapping one piece on at a time.
A plastic engine block next to the car on a lift provides the best of both worlds for checking fitment.
If you drop a piece and it splits apart use Crazy Glue to stick the two halves together. If you snap them back together without the glue, they may pop apart and cause a whole tube length to fall on the floor.
When you count the blocks to determine how long the tube is at a given point, put a piece of tape on the block and write the number down.
Use a stable piece of plywood under the engine. If a tube drops it won’t go far. If you let it hit the floor, you’ll need to start over again.
Long tubes get heavy and they can rotate or fall off. If you have plywood under the engine you can place blocks under the tubes to support them. I used step blocks from my milling machine’s clamp set because it’s easy to quickly adjust their height.
Step blocks