Routing exhaust through frame cross members?

[redss86]

I'm guessing here, but I don't see a lot of vertical loading being placed on the area of your oval pass thru's. They look nice, I might have been tempted to drill some lightening holes, but that could be risky, and for little gain. What i do see that I would suggest is two additional braces that basically continue forward, on the front side of the exhaust cut out crossmember. They would IMO be in a continuous straight line with the two existing splayed out rear braces. I suspect this area absorbs/handles a lot of the thrust loads of the rear axle, and help support the cantilever of the oval exhaust pass thru, and the current load path is partly, an inefficient z design. Just thinking out loud.



Stop the presses, I'm driving around this afternoon, and "truck arms" pops into my head, Oops, sorry, they also do transfer torgue forward into a vertical component at this crossmember, depending on how stout your combination is, you may want to gusset say on the top those oval tubes. And if you added the previously suggested extra small braces I mentioned, no more needed then a 14g material, IMO .

Ok, so I finally got back to working on this again (wife actually told me to go out and work on it). I just finished putting the short braces in that you suggested. I have not put the gussets in that you mentioned. My goal is a primarily spirited street driven, with the occasional auto cross, and road course. Planning on a twin turbo ls6 backed by a Viper t56, and a Ford 9" with a 295-315 rear tire. Max power goal is around 600-700 rwhp (maybe more?)

Here are some pics. Let me know if the gusseting is still needed.





What about putting these in here? They will also be flatten some to make them more oval. I will be using the same 1/4" wall dom tubing.



Thanks for any and all suggestions.