Titanium or Stainless Header?

They both eventually end up red/brown in the long run with the dirt. All ive ever run was TI. They all dent the same.

Ti headers are a helluva lot better then they were in the early days.

Durability-wise, I’d still have to give the nod to stainless. 

Stainless is by far more durable. Also if it does crack a hair & you catch it anybody will weld it & it’s hard to find people who want to weld ti. Running a ti cannister with a stainless header has been my go to set up 

Most of the wear I’ve seen is chafing wear on the diameter where it fits into the slip on and wears paper thin over time, then it’s junk. Titanium dents easier when hot, compared to steel. It also folds up and compresses (similar to an accordion) where it goes into the exhaust port if it takes a hit in that area that’s very difficult to repair. I’d recommend steel, which also dissipates/transfers heat better from the  cylinder head compared to titanium. The sprung weight savings is minimal

I put a T-6 system on my bike instead of the Ti-6 for durability.  Don’t know the weight difference, but it was significantly less expensive.

I'm a fanboi for titanium 

Reducing/eliminating that rust look is the main reason I was thinking of a ti header. So the Ti gets brown where the dirt from the front tire builds up too?

Wash it like normal and take two seconds to spray it down with WD40 and wipe the header. You will never have the look you are afraid of and the next time youngster the bike the header will heat the oil off and it looks brand new every time 

I am seeing the stock ktm header get that brownish look between start of a race and by the time I get home and can wash it. Yeah I noticed the wd40 smokes a lot worse than it does in a two stroke pipe. 

I always run stainless headers for durability. 

Stainless

Stainless works just fine. Its only for weight, which the difference is not enough to matter for us normal riders. Stainless has always proven more durable against rock dents.

There's so much misinformation online about exhaust materials, it's almost comical.

At room temperature, both grades of stainless (usually 321 or 347) and titanium (usually grade 4) used in exhaust systems have about the same yield and fatigue strengths. If you have cheap stainless exhaust using alloy 304, then it's about half the yield strength of titanium. At exhaust header temperatures, stainless is slightly stronger, but not be a large margin and nothing I would base a decision on.

Stainless and titanium both have the same thermal conductivity. No advantage to either there.

The main difference is that titanium will be nearly half the weight of stainless, but something like twice the cost. Simply put, weight is the primary difference between the two choices. It's possible to make a titanium header stronger and tougher, yet still lighter, than stainless, it just depends on the thickness of tube used.

I used to be also until I had no options other than stainless. Now I wouldn't go back.

Coefficient of expansion at 500 deg F for Titanium (CP, 5-2.5, 6-4, typ. Grades) is 5.2 micro-inch/in/Deg F; coefficient for 300 series stainless steel is almost double at 9.45. 

I’ve repaired 100’s of both ti and steel headers and have witnessed routine small dent damage (pings) from small rocks on the first bend of Ti headers that don’t appear on steel headers, showing the Ti grades used are much softer than steel at operating temps.

Also the amount of heat required to reform damaged Ti headers is dramatically lower than steel. The wall thickness is also 30-40% thinner than steel, and even more at the bend radius sections from oem forming. The Ti also has a higher notch sensitivity which propagates cracks faster when nicked or scratched from impact damage vs steel.

Thermal expansion coefficient is not the same as thermal conductivity, they're completely different properties. 

The titanium headers you're seeing with small dents does not at all confirm that they're softer than stainless at operating temperatures, your second paragraph is evidence of why; the titanium is thinner than the stainless. In that case, the strength difference has little to do with the material differences and everything to do with the thickness of the tube. 

My mistake, thanks for the correction had application confused with another ti project going on.  The avg thermal conductivity of ti alloys are 11 w/m-K, stainless at 16 w/m-K. 

Considering mine is currently caked with baked on dirt, yes. I need to take a scotch brite pad to it.

Titanium for moto

Stainless for off-road

I don't really understand why you're looking up values in an attempt to prove me wrong? Regardless, while you're in the looking things up mood, try looking up what titanium alloy is commonly used in exhaust, then look up it's thermal conductivity and report back. 

Hint: If you want to save the time, it's either grade 1 or grade 4 with a thermal conductivity of 16 and 17.2 W/m-K respectively. Which is the same or just slightly more than 321/347 stainless. But I do appreciate you using reasonable metric units this time!

And this brings us full circle as to why there's so much misinformation about this stuff out there... 

I run full titanium exhaust on my four strokes; currently an Akrapovic system on the Husky 350, primarily to reduce weight. I believe the full Ti system dropped about 3 pounds from the bike, which is massive.

If you're still in El Cajon, you're welcome to swing by and see it, we're only 15 minutes away in Miramar. And sorry if I seem like a bit of a dick in my responses, it just irks me when someone goes out of their way to prove me wrong, but uses incorrect information in their attempt. Twice. 

Do you know what the Akrapovic stainless system weighs in comparison to the full Ti?

I do not, sorry

I’ve had the same full stainless DRD set up on my 05 war horse. It’s been raced at mammoth twice. That place is rock hell. It’s still ticking. Over 125 hrs on that system. 

I just wish FMF would hurry up and release the 4.1 for the 450RX, this stocker is a bit of a boat anchor.

Can't wait to try your M10 handlebar mounts tomorrow. Thank you for getting those out so fast.

Unfortunately they don’t list any info for ktms. 

Titanium is a poor material for exhausts, as it becomes brittle due to Oxygen absorption over time, so while it is lighter than Stainless Steel and stronger, it will fail more than a stainless steel one. 

If you are in Pro level racing, then the weight saving is worth the risk, but after so many heat cycles, the Ti exhaust will fail. And it will fail anywhere, whereas a SS exhaust will most likely fail across a weld from microcracking in the heat affected zone of the weld that occurred during manufacture. 

Having run Ti exhausts on numerous Supermoto bikes since 2007, they all break somewhere, and no matter how good they are , one they start breaking , they will break some where else no matter how good the repair. 

The current twin pipe system on my FS450, made by Tecmo, probably has 10 hours on it, and has been repaired 3 times, all of those are brackets, it has yet to fail on the pipe itself. But it will. 

Just like Carbon Fibre, while its weight will give savings that will bring performance gains, at the point it gets hours on it, it will fail, and any repairs will just lead to failures elsewhere. 

Obviously, a lot of this is dependant of the grade of Titanium used , I know we used to use both stainless and Ti exhausts on the WRC cars i worked on, the Ti ones had a thermal layer added, which we used on Tarmac, and i think we used SS ones on the rough gravel events.  They usually died through impact damage and if they didnt, they would be carried as truck spares , if they were good enough. 

In F1 , where Inconel is the chosen material , they 3D print the header stubs and i have heard that full systems have been printed too. But they are lifed, and are tossed when their hours are up, with the best kept as spares.

It occurs to me as a write this, that i dont ever recall a Ti 2 stroke pipe.  Its obvious to say you cant hydroform Ti, but it can be done, its just very ,very expensive, and quite possibly not practical, with exhaust pipe geometry. 

Ti over stainless isn't going to make me any faster or the bike handle better so it is stainless for me with the benefit of better durability.