norvalwilhelm

The lab next to mine just got a state of the art exhuast bending machine. $275,000. They are doing research in 3 inch mandral bending. They got about 150 3 inch exhaust pipes in steel, stainless and aluminum. After a few trial bends they are turning out flawless bends. They will bend anything I want in whatever I want. My existing 3 inch stainless exhaust is heavy.
I was wondering if anyone ever tried aluminum. I can have it bent and welded but will it last? I never drive in rail but the exhaust will be eaten from the inside out I assume.

Anyone try it or heard of someone trying it?
Sure would like to save weight without costing a fortune.

Corvettes White

Interesting thought. Where do you start the system? At the headers? Alu. Headers? At the cast iron manifold? Are you running a Cat? They get very hot. I think the big question is how hot the system will get and what alloy the Alu. is. Consider the different rates of expansion between Alu and steel. Maybe a call to ALCOA. They have tried for years to build the aluminum car and may know. Failing that what about Titanium like in the new Vettes? Please post your findings, I love the idea.

George

norvalwilhelm

I would start the system after the headers. Aluminum will take the heat. Pure aluminum melts at 1220. It is alot cooler then this by the time it clears the headers. I would use titanium if I could buy it at a descent price. The aluminum pipes or stainless are free.
They are throwing the mandral bends in the garbage so I am starting a collection.
It is impressive seeing the piles of pipes. Almost 500 in total of 3 inch.
They will be getting into tighter and tighter bends plus hydra phonic? bending using hydraulic pressure inside the pipe instead of a mandral.

MikeC

Sounds very interesting. Not sure if it will work well, but if they will do it for free and you can weld the system together, why not give it a try.

427V8

OMG!
Aluminum woud SO ROCK!
Just get the pipes jet hot coated...no more corosion :D:D

I would LOVE to have a set of aluminum headers :smash:

It should be just fine, the heads are aluminum, and if your headers glow they are at 750-100c so I can't imaging they normally get above 500c...

PRNDL

What part of our "aluminized" pipes is aluminum ? MJ


"Aluminum" being one of those words you can't say more than 3 times without it sounding really strange....

gkull

I'm not a Metallurgist. But you never see aluminum pipes on race cars that are trying to save weight.

I think that the problems with aluminum would be the amount of expansion and it's tensile strength is low to begin with and it would really go down as the heat goes up. So it would be very prone to cracking and the mounts would have to be nearly free floating to allow for diameter and length changes.

shawn_cake

I'm worried about bending titanium - I think the Young's modulus is way too low for tight radius bends. I am trying to build some turbo headers out of Inconel or Titanium. Norval - Could you look this up in your ASME tables?

Thanks!

:cheers: :cheers:

norvalwilhelm

I'm worried about bending titanium - I think the Young's modulus is way too low for tight radius bends. I am trying to build some turbo headers out of Inconel or Titanium. Norval - Could you look this up in your ASME tables?
Thanks!

Modulus for steel is 300 x 100000 or 30 million
titanium and it's alloys is 190
inconel is 310

427V8

I think it's just a coating over the steel pipe...

Pete79L82

Thin wall aluminum tubing will not heat cycle very well. I built some aluminum exhaust for my race car quite a while ago. Only got about 2 night of racing on them before they started to crack. By the fourth night they where junk.

Most exhaust tubing that refers to aluminum is "Aluminized", which is an aluminum coating over steel tubing to keep it from rusting.

Dalannex

What kind of bender is it. I mean what brand and model number. I used to manage a factory that bent steel tubing. We made everything from frames for large equipment cabs to hydraulic lines to brake lines. We did it all from 1/8" on up to 4.5" in diameter. We used all CNC controlled Eaton Leonard machines with all the bells and whistles from controllable pressures to vector corrections. Boy could a guy ever bend up some mean exhaust with one of those babies. Of course, at a couple of hundred grand a pop it would be hard to justify. :)

flood

Quit skimping out. Aluminum is nice but titanium is soooo much nicer :jester

Noel Carboni

Dang, you have my envy!

I'd go for stainless.

-Noel

Garys '68

Good idea, but aluminum will crack. That's especially true of any areas that are bent. I've done a lot of work with aluminum in boats and any AL part that is subjected to flexing ALWAYS fails. I have used AL for exhausts pipes on boats, but it had to be isolated from any stresses. Try S/S.
Gary

norvalwilhelm

Guess I can forget about the aluminum exhaust. I already have a stainless one. I will just continue to collect bends and lengths of pipe for future. They will be trying for tighter and tighter bends.
I don't know the make and model but it is about 30 feet long and is totally computer controlled. The pipe is fed in and it automatically rotates it, pushes it along, bends it but most important is the internal mandrel. If it is out by 1/4 of an inch the bend does not come out perfect. Eventually they will use hydraulic pressure to form the pipe.