3" pipe above rear on a 240z?

[2savage]

I'm building a rally car using a '73 240z. Headers are stahl, ending in two 2 1/2" tubes, then through a flowmaster Y to a 3" tube. I need to build the rest of the system back and need maximum ground clearance. Is it possible to go above the rear suspension?

[Pop N Wood]

Not really. Not without cutting into the cabin sheet metal.

 

What you can do is a Ron Tyler style diff mount. That will allow you to thin out the front crossmember some

[Tony D]

Run dual 2.5" tube all the way back, then package accordingly. If you use the early 240Z differential crossmember you can hang the tubes like the stock Z432 Exhaust (twin 50mm or 60mm pipes) and all the exhaust will be invisible from the side... WELL up in the tunnel, and above the lower portions of the Framerails. The 240 diffy crossmember has the cutouts for dual exhausts. There is a reason those early cars ran the tubes straight out the back in twin pipes! FYI, twin 50mm pipes flow as much as a 2.78" single. Twin 2.5" pipes will flow similar to a 3.54" Single, and packages easier! Sucks up nicely and tightly if you use hangers at the rear just like the stock 432 Exhaust.

[Pop N Wood]

The 240 crossmemmber has about a half inch recess on the passenger's side. Not enough to make a difference in hanging an exhaust. The 240 crossmember is also considerably less beefy than the later units.

 

What I plan on doing is swapping out my 240 unit and modifying a later R200 crossmember to include cutouts on both sides. Since I added the Ron Tyler style diff mount I can safely cut into the crossmember.

 

You can kind of see the extra cut out in this picture of an R200 and early R180 crossmember

 

[Tony D]

I don't know about anyone else, but my twin 50mm pipes don't rub, and are not visible as a lowpoint using a 240 mount and proper hangers like the Z432. The divot may be 'small' but it's enough to properly hang a 60mm tube under there with no interference issues, and will keep your exhaust from being a low point.

 

I don't know, maybe I'm a talented exhaust system installer, but it's not been a problem using the OEM fittments on several cars I've installed this same style exhaust.

 

For a single 3" exhaust, no doubt the later 280Z mount is better, the cutout is much larger and allows you to stuff the huge pipe up further to get it clear of everything..

 

But for twins in the 60 mm range ( almost 2.5"...2.36" I believe...) using the stock 432 Exhaust hanging setup and early differential crossmember should present absolutely zero clearance issues, appearances and intuition to the contrary notwithstanding.

 

You can force something under there that wasn't designed to fit, or you can put it under there like the original engineering intended, and benefit from MUCH greater flow potential for a healthy engine compared to the single monster tube. Seems like a no-brainer if you don't want to rework a bunch of stuff. Just because it didn't come that way here doesn't mean we can't use the holes in the chassis, right?