I was talking to the guy that is fixing my transmission and we were discussing something.

I have factory style exhaust and I think I am correct on this.

Isn't it correct that you have it bolted to the headers and then on each side you have two of those straps for hangers as you go back down the car? Total of four hangers...two on each side.

I believe each side on mine has a hanger around the backseat area somewhere and then another attached to the frame rail near the back of the car.

He seemed to think there was supposed to be another hanger on each side further up but I honestly don't believe so.....I do need to eventually get an H pipe but I don't believe there are supposed to be any additional hangers up there....

 

Well, 'factory' didn't have manifolds But aside from that, I don't believe there were hangers in the front originally, no.

 

I didn't think so either just because when I bought my car it didn't have any other hangers and looking at the mounting kits you can buy they don't include any additional hangers either...not that how my car was set up when I bought it means much though since the kid that used to own my car was known to cut corners and jerry rigg things. I am still convinced I will find a coat hanger or duck tape holding something together eventually. I literally did find a paper clip holding one thing together and have spent hours correcting things of this nature since I purchased the car....missing screws you name it.

The car my exhaust came off of had the same type of set up with only two sets of hangers on each side also so I figured that was correct.

 

This is an interesting debate. Most complete dual exhaust system manufacturers only include the two mounts per side in the places you described, however, most header manufacturers that offer a warranty will not honor it if you don't also support the exhaust up near the collectors. They say the header is not designed to support the weight of the exhaust system and the collector welds will crack. Obviously, this is not an issue with cast iron manifolds.

 

Really. Hmm. Never heard that before.

 

Here's an example, check out the Special Instructions at the bottom of the page:

http://static.summitracing.com/globa.../hed-88360.pdf

Others are not this specific, but say the warranty is void if improperly installed. If you return them due to cracks in the collector or where the primaries join the collector and you don't have a support behind the collector, they will not honor the warranty.

 

I have Alum heads my exhaust only has the 2 supports near the rear... I can't think of any car that has exhaust up by the front????

 

Note that the Summit link specifically calls out a rubber hanger for the forward one. This is important, as these additional hangers are intended to support only the dead weight of the exhaust piping, along with some of the vertical g-forces on the exhaust piping that happen as you encounter bumps and heaves in the road. They are NOT intended to resist loads that occur due to thermal expansion of the exhaust system or rocking of the engine as the engine torque reactions squeeze/stretch the rubber in the engine mounts. So you need to be close enough to carry the weight but far enough to not pick up much from the other loads (which can be much worse in a really badly supported system).

Truth be told, you could use alternate hanger methods as long as they are somewhat flexible against loads caused by thermal expansion and engine displacement. Those loads can crack the welds even sooner than weight and inertia loads will if these hangers are too rigid or located too close to the header for their stiffness. Thermal expansion grows down and rearward from the header connections to the heads. Torque reaction is one side up/other side down and can be in either sense (driver side up/down, pass side down/up).

I really wish that Hedman had been more specific about their "rubber hangers". The cheapie kind at the Pep Boys/Autozone/etc. are not all that flexible in at least one direction, and I'd be inclined to mount them at least a foot downstream of the weld of the exhaust pipe to the reducer. Or modify them somehow to be more flexible while still carrying the weight loads.

Piping stress analysis and such has been my day job for, ummm, a while . . . exhaust systems are only smaller diameter/thinner metal than most of the stuff I get paid to analyze.


Norm

 

The fact that your heads are aluminum has very little bearing how on everything downstream should be supported.

Stock exhausts may have joints that permit a little rotation without leaking, which to some extent alleviates the expansion and engine rotation loads seen by the piping and its supports.

The braided flex hose that you see on most (maybe all?) transverse-engine FWD cars is another solution. Support immediately behind it/them.


Norm

 

Ther eshould just be two hangers on each side. One attached to the rear of the muffler and the other near the end of the tailpipe.