Why no aluminum???

[Dimman]

^ So basically if the exhaust is very thick-walled, rigid and water cooled, aluminum will be perfect?

[OrbitalEllipses]

Originally Posted by Dimman

^ So basically if the exhaust is very thick-walled, rigid and water cooled, aluminum will be perfect?

I was about to ask what manifolds cast into heads have to do with thin ass piping.

[Dimman]

Originally Posted by OrbitalEllipses

I was about to ask what manifolds cast into heads have to do with thin ass piping.

It is interesting that manufacturers are moving in that direction, but I suspect it has a bit to do with reducing the amount of assembly time and parts. Could also be used to control EGTs better so they don't overcook the cats, too.

[noAE86]

this is starting to remind me of the arguments when plastic intake manifolds where coming into production,

[arghx7]

Originally Posted by Dimman

^ So basically if the exhaust is very thick-walled, rigid and water cooled, aluminum will be perfect?

The Civic and Chrysler V6 engines are not using water cooled manifolds.

The water cooling is for turbo engines so that they don't have to enrich the mixture nearly as much to keep cat temps down. Any way you look at it, it's still an aluminum exhaust manifold whether it's bolted or casted to the head.

[Neziah]

Well since they are already making a casting, anything you can combine in to it saves tooling and production cost as well.

[Dimman]

Originally Posted by arghx7

The Civic and Chrysler V6 engines are not using water cooled manifolds.

The water cooling is for turbo engines so that they don't have to enrich the mixture nearly as much to keep cat temps down. Any way you look at it, it's still an aluminum exhaust manifold whether it's bolted or casted to the head.

I know you know your stuff and that manifold/extended head is interesting. But I was just presenting things a little differently, since I have this image of some noobs welding up a bunch of aluminum intercooler piping as an exhaust and wondering why it fails 6 months later.

[HunterGreene]

Comparing manifolds to cat-back/axle-back exhaust systems is like comparing apples to oranges. They are constructed different, as Dimman said.

And whoever said it was correct--304 stainless (which is the standard in the industry) is the best price/weight/durability currently for exhaust systems.

[Dave-ROR]

Originally Posted by HunterGreene

Comparing manifolds to cat-back/axle-back exhaust systems is like comparing apples to oranges. They are constructed different, as Dimman said.

And whoever said it was correct--304 stainless (which is the standard in the industry) is the best price/weight/durability currently for exhaust systems.

[thermobox]

But c'mon guys. We can combine 4 turbo cylinder heads and two non-turbo cylinder heads to make an extremely light weight exhaust? Whiskey Tango Foxtrot? What the hell is going on inside this thread?
If Aluminum was the way to go, wouldn't all of the aftermarket Mfrs already be doing it? They don't make it because it makes no sense.

Yes, you can use Aluminum all over a car in high heat applications, just not the actual piping of an exhaust.

[Jason@Nameless]

This would all make sense if the bottom line wasn't "that is too loud for my local track."

Aluminum axleback is about a 2lb savings over a 304 single exit. Factory midpipe is 18ga (thin) stainless. We might take a crack at an aluminum midpipe. But thus far we haven't found good enough pricing on Ti 2.5" tubing to make it worthwhile.

And from what I have read in the metallurgy literature, bonding is a better solution than welding in most cases. Not sure how the high strength and fatigue resilient epoxies will withstand oxidizers and temperature like found in exhaust gas. Same can be said of aluminum in general. Kinda tough to anodize a 7' long pipe. But if it was a known seasonal consumable, that'd be a different story.

J

[serialk11r]

Originally Posted by Jason@Nameless

And from what I have read in the metallurgy literature, bonding is a better solution than welding in most cases. Not sure how the high strength and fatigue resilient epoxies will withstand oxidizers and temperature like found in exhaust gas. Same can be said of aluminum in general. Kinda tough to anodize a 7' long pipe. But if it was a known seasonal consumable, that'd be a different story.
J

How about not fixed at all? Silicone seals (good up to 500C or something) and some kind of slip fit thing? And then for mounting maybe add a structural support extrusion of some sort, held onto the pipe with silicone as well.

[Motordyne]

Originally Posted by Dave-ROR

Here you go: http://www.lmgtfy.com/?q=why+isn%27t...d+for+exhausts

LOL! That's awesome!

[JDLAutoDesign]

Titanium or bust!