Titanium exhaust system.

[288gto]

I have the opportunity of having a full exhaust system being made in titanium and wondered firstly if anyone else on here had one or experience with a titanium system.
I am told that the sound is more like a steel system and again would be interested to know if anyone can confirm this.
The main advantage is that it would be about half the weight of stainless.

Thanks in advance,

Simon

[bitsobrits]

Half the weight and 4 times the cost?

[Series1 Stu]

I don't understand why anybody would want to fit a titanium exhaust on a road car, unless they absolutely had to save the 20kg or so it would save.

Titanium is indeed higher tensile strength and lower density than stainless steel but it is more brittle and prone fracture due to it's relatively poor impact and shear strengths. Not ideal to hang under a car and expose to the sorts of things we find lying in the roads.

If you want an exhaust that sounds like a steel exhaust the why not buy a steel exhaust?

Cheers

[288gto]

That's an interesting point as regards it being more brittle Stuart, thanks.

The other option is Inconel 625 which is apparently more resilient to fatigue, what would your thoughts be on this.

I'm not trying to go all exotic with the exhaust just for the sake of it. It turns out a contractor we use makes custom exhausts for Motorsports applications including Mclaren.
I have the choice of Stainless, Titanium or Inconel 625 or a combination.
I definitely don't want mild steel.

Thanks again

Simon

[Series1 Stu]

Hi Simon

I don't know much about Inconel 625 other than its got excellent corrosion resistance. It is about 6% more dense than stainless steel and has similar mechanical properties although it will gain in strength and stiffness with age.

My only problem with it is, what then do you do with it? Very few people will be able to do anything with it, other than the specialist you mention. Motorsport exhaust systems are not expected to last as long as those for road cars or see the same range of operating conditions.

I have an expensive stainless steel system on mine and it does sound rather tinny. I've decided to investigate ways of altering this resonance when once the car is on the road.

Regards

[288gto]

Thanks again Stuart, another possible advantage of the custom made system is that they can make it so that the silencers are re packable.
Early days yet as I've only just got the engine back. About 5 years ago I bought a stainless Bell system from SNG when they were on offer but the project has moved on a bit in terms of spec since then so it's still in its original box and won't be fitted.

Simon

[cactusman]

I would tentatively agree with the comments 're titanium as it is brittle...although I would not be surprised if your titanium was actually a titanium alloy as it is usually alloyed with iron, aluminium, vanadium and sometimes magnesium to improve its strength and machinability. There are many inconel alloys too. Basically Nickel and Chromium with all sorts of other metals including iron, molybdenum and manganese to name but a few. Very resistant material. Of the three I would choose inconel over stainless steel over titanium.

If you want mild steel then fine but it is bound to rust. To me a no brainer...use a better material than cheap mild steel.

[cactusman]

One other thing....titanium will, given enough encouragement burn (and it would need a lot of encouragement). A very very unlikely scenario in a car but if ever it did catch fire in an accident then almost impossible to extinguish. Using water would be catastrophic.

[Series1 Stu]

Perhaps I should have been more specific. I was discussing titanium alloy grade 5, 304 stainless steel and, as Simon stated, Inconel 625. These are what I based my statements on.

I also said I have a stainless steel system on mine.

The mild steel comments were regarding their aural qualities, which has been the subject of much debate. That said, my Audi quattro still has the mild steel system it left the factory with over 23 years and 120k miles ago.

As for flammability, any material will burn given enough encouragement. I would be more worried about the amount of aluminium in a car than anything else. Although even then it only really presents a hazard due to it's low melting point, not through burning.

I'm sorry, I just don't see the point of using exotic materials when they just aren't necessary.

Regards

[Series1 Stu]

Perhaps I should have been more specific. I was discussing titanium alloy grade 5, 304 stainless steel and, as Simon stated, Inconel 625. These are what I based my statements on.

I also said I have a stainless steel system on mine.

The mild steel comments were regarding their aural qualities, which has been the subject of much debate. That said, my Audi quattro still has the mild steel system it left the factory with over 23 years and 120k miles ago.

As for flammability, any material will burn given enough encouragement. I would be more worried about the amount of aluminium in a car than anything else. Although even then it only really presents a hazard due to it's low melting point, not through burning.

I'm sorry, I just don't see the point of using exotic materials when they just aren't necessary.

Regards

[66an]

Go for titanium. I don't know what my experience is worth as it's not from an E-type but my previous car was a Corvette Z06 with the stock titanium cat back system. It´s incredible lightweight. My experience is that it´s not the same sound as in a typical stainless system. The pipes that are closest to the engine will be coloured blue/purple by the heat.