I am fabbing up a 2.5" downpipe. It's going pretty well, but I think I may be too close to the intermediate shaft. I only have about 1 cm clearance.

What do you think? Is this OK, or should I start over and route it closer to the the Tranny? Any rule of thumb on how much clearance should be allowed for engine movement?

-Keith

 

a zoomed out photo would be useful.. it's confusing that close up. 1cm is fine provided you are on the side of the shaft nearest the fender (as that is the way the engine torques it will increase to 2-3cm under load). I doubt you'll see 1cm deflection in the mounts under decel. If it is on the other side of the shaft you may want closer to 2-3 cm.

 

It is made from steel, it isnt going to melt or corrode. Consider how close the stock manifold is to it.

 

Do it closer to the tranny. I made mine about 1-2 cm to the steering shaft, and every so often they would bounce off of each other causing the entire car to shake. Take my advice, run it closer to the tranny, and then make a bracket so it bolts to the same bolts the OEM mid pipe bolted to.

 

Mine's that close and I have no problems. The part in the pic is a 2.5-3" transition.



but the 3" pipe is tight EVERYwhere. 1cm is typically a max clearance on my setup. 2.5 should be a walk in the park.

 

I decided to leave it. I broke the tack welds and tried some different arrangements of the bends but my first attempt seemed to be the best. I just put it back the way it was.

 

yeah. the motor wont move that much -- especially with stiffer mounts -- and hte steering shaft is not going to heat up or cause problems.

 

y8s- Any problems with the 3" going through the rear axle or did you just dump it? Have a picture of that cause if 2.5" is tight going through there i can't imagine 3".

 

The 2.5" is doable. The 3" is very tight everywhere and takes a lot of patience.
-Michael-

 

You usually go under with a 3"

 

I did 3" under like WOT- flanged after the diff so I can swap out mufflers, in a "straight out" section. I decided to try this out after some rear ended the car and scraped up the bumper. So far it's worked reasonably well for space- left room for the spare under there too.

WOT - are those poly hanger bushings?

 

pff piece of cake. even with the extra cross-brace under the diff! almost a whole 1/4" of clearance all around!

Current version with the big magnaflow stealth muffler:


note that I did have to take a little off a little square diff housing boss.

Old version with the loud-*** dynomax:
http://www.y8s.com/gallery/turbo/DSC00676

So yeah I ground the boss on the housing down to make tons more room. It's MUCH better now with the magnaflow and extra ?-shaped pipe that's done how the stocker is.
The boss is pretty clear here on the right:
http://www.y8s.com/gallery/turbo/DSC00678

 

I don't believe I've ever seen anyone go over the diff. with their exhaust on a Miata

 

Holy crap y8s, i just spent a half hour looking through all of your images at http://www.y8s.com/gallery/turbo very impressive!

 

thanks. there's more at www.y8s.com/gallery/miata if you want to see em.

 

2nd. Good stuff.

 

Y8's Nice Job!

Yes i was running poly hangers. My entire straight section of the exhaust was a Magnaflow resonater that just barely fit. With the poly hangers the exhaust never bumped anything.

 

I need poly hangers (goodwin is on backorder). I had hose clamps around my rubber hangers to keep my big muffler and extra-deep trunk floor (dont ask) from meeting. There was like 3/8" clearance or less.