Custom Fab Titanium Exhaust

[GSXRJJordan]

Originally Posted by Def

I've got a few shelves full of mandrel bent titanium tubes at work, so it's very possible. It wrinkles less than aluminum tubing of the same diameter and wall thickness.

McLaren F1's stock headers and exhaust system are titanium, and they're all mandrel bent. I think the Corvette ZR1's exhaust is titanium as well, and I can guarantee you they aren't pie cutting that thing.

Very cool info. Apparently I'm blind, or haven't been looking hard enough.

Aluminum, to me, is the easy choice here for cat-back stuff... doesn't corrode /rust (like mild steel) much, is reasonably cheap (about double the cost of mild steel, less than half the cost of Ti), and almost as light as Ti.

Oh, and the Z06 and ZR1 exhausts are Ti, but they're covered in heat shields. I'll have to get a peek at the bends the next time I'm under my dad's C5 Z06.

[misfitsfreak81]

Originally Posted by GSXRJJordan

Very cool info. Apparently I'm blind, or haven't been looking hard enough.

Aluminum, to me, is the easy choice here for cat-back stuff... doesn't corrode /rust (like mild steel) much, is reasonably cheap (about double the cost of mild steel, less than half the cost of Ti), and almost as light as Ti.

Oh, and the Z06 and ZR1 exhausts are Ti, but they're covered in heat shields. I'll have to get a peek at the bends the next time I'm under my dad's C5 Z06.

you would have to use pretty thick aluminum tube to keep it from melting. the heat transfer property of aluminum are way different than any form of steel. it also has a far lower melting point than steel. the heat from the cat alone would most likely destroy an aluminum exhaust, let alone the temp at the rear of the car in the bumper opening would be only a couple degrees different than right at the cat. just to clear things up, aluminum is not actually lighter than titanium. its just that ti is so much stronger it can be used in far thinner thicknesses with superior strength.

thanks

Mike
North Shore Performance Auto

[Def]

Originally Posted by misfitsfreak81

you would have to use pretty thick aluminum tube to keep it from melting. the heat transfer property of aluminum are way different than any form of steel. it also has a far lower melting point than steel. the heat from the cat alone would most likely destroy an aluminum exhaust, let alone the temp at the rear of the car in the bumper opening would be only a couple degrees different than right at the cat. just to clear things up, aluminum is not actually lighter than titanium. its just that ti is so much stronger it can be used in far thinner thicknesses with superior strength.

thanks

Mike
North Shore Performance Auto

Aluminum will have a lighter density, and you can use more material to get a stiffer structure. Strength depends on many factors, but generally Ti will be stronger.

That said, aluminum works fine for a catback exhaust. Melting point for aluminum is in the 1050-1100 deg F range, and it loses significant mechanical strength around 700-800 deg F. So while the exhaust temps might be around the melting temp, aluminum will have a much higher rate of thermal conductivity than any other exhaust material so it will shed more heat to the ambient air and more of it will stay cooler. Lower material temps mean better mechanical properties.

The short of it, aluminum has been shown to work just fine for an exhaust at least a few feet away from the exhaust ports on tons of cars.

[misfitsfreak81]

Originally Posted by Def

Aluminum will have a lighter density, and you can use more material to get a stiffer structure. Strength depends on many factors, but generally Ti will be stronger.

That said, aluminum works fine for a catback exhaust. Melting point for aluminum is in the 1050-1100 deg F range, and it loses significant mechanical strength around 700-800 deg F. So while the exhaust temps might be around the melting temp, aluminum will have a much higher rate of thermal conductivity than any other exhaust material so it will shed more heat to the ambient air and more of it will stay cooler. Lower material temps mean better mechanical properties.

The short of it, aluminum has been shown to work just fine for an exhaust at least a few feet away from the exhaust ports on tons of cars.

Aluminum has a melting point between 1050 to 1150 degrees Fahrenheit, yet it gets soft and unstable at far lower temps. here is somthing interesting that i found.

ANSI B31.1 (Power Piping Code, 1980 Edition) neither lists allowable stresses for aluminum for temperatures in excess of 400°F nor permits its use at such temperatures. While it's true that exhaust plumbing isn't power piping, it's still a reasonable guideline to follow, and material that's only good to 3000 psi at 400°F will be utterly worthless at 1000°F.

The end near the muffler would corrode do to the combustion gases combined with moisture form Hydrochloric, Sulfuric, Nitric, Carbonic and other acids. That's why the back end of normal carbon steel systems rust out and the real reason stainless steel systems originally started (not the bling factor!)

the bottom line is yes, you can make an exhaust out of aluminum. no, it wont last long. yes, it will be light. yes, you will have to replace it offten.

thanks.

Mike

[Def]

Originally Posted by misfitsfreak81

Aluminum has a melting point between 1050 to 1150 degrees Fahrenheit, yet it gets soft and unstable at far lower temps. here is somthing interesting that i found.

ANSI B31.1 (Power Piping Code, 1980 Edition) neither lists allowable stresses for aluminum for temperatures in excess of 400°F nor permits its use at such temperatures. While it's true that exhaust plumbing isn't power piping, it's still a reasonable guideline to follow, and material that's only good to 3000 psi at 400°F will be utterly worthless at 1000°F.

The end near the muffler would corrode do to the combustion gases combined with moisture form Hydrochloric, Sulfuric, Nitric, Carbonic and other acids. That's why the back end of normal carbon steel systems rust out and the real reason stainless steel systems originally started (not the bling factor!)

the bottom line is yes, you can make an exhaust out of aluminum. no, it wont last long. yes, it will be light. yes, you will have to replace it offten.

thanks.

Mike

The pressure inside a catback is barely above ambient, so that's not a design consideration.

TONS of Hondas have proven aluminum cat back exhausts work just fine. They don't stand up to scraping as well as stainless steel due to being softer, but other than that no reason it wouldn't last a very long time if it is properly designed.

The minimal acid exposure will affect 304 stainless about as much as 6061 aluminum.



As for the thickness of the Ti, I definitely wouldn't go over 0.035" wall. 0.028" wall should work just fine if you support it well(full wrap around hangers and gussets on the flanges).

[misfitsfreak81]

Originally Posted by Def

The pressure inside a catback is barely above ambient, so that's not a design consideration.

TONS of Hondas have proven aluminum cat back exhausts work just fine. They don't stand up to scraping as well as stainless steel due to being softer, but other than that no reason it wouldn't last a very long time if it is properly designed.

The minimal acid exposure will affect 304 stainless about as much as 6061 aluminum.


As for the thickness of the Ti, I definitely wouldn't go over 0.035" wall. 0.028" wall should work just fine if you support it well(full wrap around hangers and gussets on the flanges).

Right on, I appreciate the info. Currently Im not planning on doing any aluminum exhausts though. In the future it is something I may play with just to see how long they would hold up. Im sure some of it would depend on where people live and what kind of conditions they drive in as well as the conditions of the roads.

Originally Posted by spartanmisfit

I'm ready for this to be done. Are you going to sell just the mufflers too? I alreadys have 2 full exhaust systems but I hate both of the mufflers.

I can get just the mufflers if thats all you are interested in. Im ready for this to be started as well. however my suppliers are somewhat dragging their feet. its kinda to be expected though for the order size im looking for. if i had $20000 to order a few hundred feet at a time im sure theyd be doing backflips to fill my needs. let me know if you would like me to get you a price on the muffler. thanks.

Originally Posted by 95KA-Turbo

I would be willing to take measurements from my Trust DD if you want.


Also, I would recommend looking into 2.5" or 2.25" piping. You will gain massive amounts of ground clearance if you run 2 pipes rather then one single pipe. I can understand this might not be feasible on the pricing you're aiming for...but if it is I'd highly recommend it!


In case you were unsure, the Trust DD is a single pipe into a muffler, then two pipes coming out of the muffler (about a 1.5 fee before the diff) that open up into ~3.5" oval slanted tips.



Fujitsubo makes an exhaust that is 2 pipes the whole time, and basically has more ground clearance then the stock exhaust. I will edit in some pictures of it if I can find them.


Here is the only picture I can find of this exhaust....it isn't very good, but you get the point.





The muffler they're using is super thin because of the two pipes.

yeah messurements would be great for the DD. using two pipes would get great ground clearance but would more than double the price just because of material costs.

Originally Posted by C-unit

Thanks for the responds..I am thinking..better yet, i'll send you a stock exhaust for mock up if everything works out within budget.

yeah you could certainly send me a stock exhaust. right now i have access to my s14 and also a s13. it would be great to get a skyline one and maybe and fd3s as well.

thanks again everyone. I hope to have prices up tomorrow. keep checking back and feel free to shoot me any questions or suggestions.

Mike
North Shore Performance Auto

[95KA-Turbo]

You will need to use two pipes at some point if you're going to make it anything like a Trust DD. The reason that exhaust is so saught after (other then the fact that it sounds amazing and looks great) is because of the ground clearance it offers.

Not to say that people wouldn't buy more of a Dart Izumi styled exhaust...but I just know I wouldn't because to put a muffler under a car that has 3" inlets and outlets requires that the muffler be at least 4" thick. Not to mention there isn't enough room to bend the exhaust up high enough near the diff to offer as great of ground clearance as the DD offers.....unless you can get oval piping, which would be freaking awesome!


I know my muffler hits on speed bumps and what not and it hangs ~1" lower then the "frame rails" under the car. Most of my friend's exhausts hang a whole inch lower then mine does.

I fully believe that if you have a S14 to build this exhaust on you wont have any issues with making it tuck up extremely well. It just wont be as effective as having two pipes (at least in the rear section).





Let me know what sort of measurements you need.