Being the kind of guy that I am, I've always hated the marginally better results with a Y-pipe into a single exhaust with longtubes. After fabbing up a 3" true dual setup on my Z28 I decided to do a reasonable setup on my IROC-Z that took into consideration ground clearance and cost.

I have a tuned port LT1 (yeah, thats right ) in my '86 I just finished up. Well, I made a y-pipe for it and was not at all satisfied with it from a performance standpoint so I'm pulling the borla and completely re-doing the exhaust. Being a guy who likes to fab with metal, I figured I could come up with a pretty decent solution with a little work.

For those of you wondering, here's why. On a thirdgen, the tunnel seems to be tucked in pretty close to the 700-R4 or 4L60-E. Because of this you have no choice but to run the pipe under the crossmember making it low to the ground no matter what you do. I figured this was unacceptable, and there is ample space on the passenger side where the cat was, so I decided to run the pipes over there, necessitating a need to modify the header to change direction so I could accomplish just that. It also helps me avoid the pain in the *** I had when trying to squeeze in minicats on my '94.

I'm pulling out the hedman longtubes in the car now and will be replacing them with hedman D-port's to fit the LT1 heads. Both headers are going under the knife...the passenger header will be a minor change, with me just turning the collector 45 degrees toward the passenger side of the car towards where the original cat was.

The driver side header is getting cut and diced up to be rotated as to where it will run across the engine something like stock. I realize this will require more mods to work but thats fine...after this has been welded up and test fitted both are getting coated, and I will be running 3" pipe for the first 18 inches and I will be reducing it down to 2.5" into an X and running out the back of the car, over the axle. It's going to incorporate 2 flanges after the X so it can be removed in sections as well as having the tailpipe sections removable as well.

All pipe is going to be mild steel. Stainless was a BITCH to weld compared to mild steel like I did on my last setup. I'm also ditching a bender and running all bends with formed 45 or 90 degree pipe so I dont create pinch points at the bends, so it's the correct ID all throughout. Should take a weekend to do. I'm also looking into welding up a skidplate to protect the collector and a heatshield as well to protect the oil from heat, so I dont put much coin into the factory LT1 oil 'cooler' which is really just a temperature stabilizer.

I'm leaving Iraq on leave in a couple days, hopefully my headers are at the house so I can get started when I get there!

I must really love duals to do this, lol! While I'm at it, I'll be fabbing up a cold air intake, since none really exists for a TPI intake in an Fbody with an LT1 MAF sensor.

I know it will be a pain in my derrierre, but considering I've built duals in F-bodies before and made the car the monstrosity it is (actually I've done weird junk to all of them lol), I think I can handle it Any thoughts? Pics to follow when I get started... and I have yet to decide on mufflers anyway, but I want a semiquiet muffler that will be in the stock location, meaning they will need to be somewhat small.

After this, it's on to sealing up the A/C. Yet another pain in my keister with F-body accessories.

 

I like your idea but You could also consider using rectangular exhaust tubing like they use in nascar. Then you should be able to keep the exhaust on both sides like most duals. I currently have true duals on my car and plan in the future to run the nascar type tubing and running them out the sides through the ground effects behind the doors with bowtie tips. I like my current setup and it wouldn't have been a problem if I had replaced the front struts when I put it on. I'd post some pics but it won't let me cause I already posted it in the dual exhaust thread already. If you want to see it I'll send it to you through pm. Keep me posted and tell me what you think of the rectangular tubing.

 

sounds like a great project. I'm looking forward to pics. Maybe a chambered muffler to keep the sounds down.

 

Are you referring to ovulated tubing? I usually use that in places where it's damn near impossible to get adequate clearance or to get more clearance with frames, etc so it doesnt rattle. Problem is, I feel kinda queasy about transitioning to oval then going back to round. Thats one of those calls I will make when I am under the car and have a better idea of what I have to work with, since I am not there right now...

 

It looks more like a rectangle to me but I'm pretty sure were on the same page. Keep us posted. Hope you make it home ok.

 

i lost no ground clearance by modifying the crossmember, im using headman lt's and s bend to the midpipe back, very simple. no ground clearance lost

https://www.thirdgen.org/forums/exha...s-notched.html

check out my pics in there