TRNorBRN6001
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posted December 06, 2007 06:58 AM
Ti Valves????
Just curious how the ti valves were holding up in some of these newer bikes? I think a couple of the 1000cc bikes have them and then the new Busa I believe is suppose to have them as well.
I have heard that there were previous issues with them on other applications. I heard from some that they would beat up the seats and I also heard from others that they were getting beat up themselves, as well as being too brittle/hard.
I also heard that some head porter people would cryo-harden either the valve or the seat to alleaviate whatever the problems were. Any comments on this?
Also curious how they hold up with nitrous applications?
Thank you all much,
Gary
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tcchin
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posted December 06, 2007 08:41 AM
Ti valves are coated to increase their surface hardness. If they were not coated, the stainless steel seats would hammer them in no time. Likewise, if the coating wears off, the valve wear will accelerate quickly. This means that the Ti valves cannot be lapped or ground and that great care must be taken when cleaning them (no abrasives). This also means that doing a valve job will require the replacement of all of your valves ($$$). Of course, if you can run beryllium copper valve seats and guides (as Del West recommends)($$$$$), which have a similar hardness to the Ti valve material, then you should be okay.
I don't believe in cryogenic hardening. When I was in grad school, there was an article on it in an issue of Roadracing World, which I showed to my metallurgy professor. He's British, so he said that the article was bollocks. Even if it did work, having a brittle valve would not be a very good idea in an impact-intensive application like valvetrain.
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TRNorBRN6001
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posted December 06, 2007 09:47 AM
"Bollocks" ----- is that similar to a set of bull testicles?
Metallurgy professor - cool, wish I could get a job like that! Might just give me a reason for
a smoking Jacket.
Just curious what do they coat them with?
Also curious if Ti valves are more sesitive to heat/cold, and/or oxidative reactions?
I am not planning on running any on my bike, but possible purchase of a Busa head down the road may require a little knowledge.
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Megabyte
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posted December 06, 2007 02:40 PM
Great Thread. The latest and greatest isn't always, if you know what I mean.
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tcchin
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posted December 07, 2007 08:52 AM
I don't know what the coating is - the valve suppliers were not very forthcoming with this information. It also varies from manufacturer to manufacturer. My guess would be TiCN or TiALN on the dark-looking valves and TiN on the bright-looking valves.
Ti is very good in terms of oxidation and heat resistance. That's why it's used in high temp aerospace applications, like jet engines and rocket engines.
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Texas12R
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posted December 17, 2007 06:31 AM
Beryllium copper hardness rockwell "b" scale 90-115
CP Ti "b"scale 70-100
interesting that BE copper had no coefficent of thermal expansion listed
As with all my comments I reserve the right to be wrong, but I thing some time ago
some engines came from the factory with stellite coatings on the valves and seats,
but as Tim pointed out the softer of the two should take the brunt of the wear.
Stellite does exisit.....but I dont know if it is available to the general public
http://www.icstechnologies.com/brands/stellite.html
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Nukedog
Expert Class
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posted December 30, 2007 09:13 AM
 Edited By: Nukedog on 30 Dec 2007 09:15
http://www.freepatentsonline.com/5169460.html
http://www0.nsc.co.jp/shinnihon_english/kenkyusho/contenthtml/n88/n8815.pdf
http://www.freepatentsonline.com/5662745.html
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zrxdean
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posted December 30, 2007 09:37 AM
I just ordered a set of stainless exhaust valves to replace the Ti ex valves on my ZX10 - as I am told the Ti cannot withstand the temps typical of turbo apps - 1500+ F.
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chavcat
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posted December 30, 2007 09:48 AM
OEM Honda valves in from 79 on in the pentproof heads came stellite tipped.
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tcchin
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posted December 30, 2007 10:22 AM
Ti actually has a higher melting point than steel, but I have no experience with its strength/temp performance. I assume the CRES valves are heavier and will require stiffer springs.
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zrxdean
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posted December 30, 2007 12:11 PM
The reasoning I was told (Rob Muzzy) is that Titanium "oxidizes and turns into dust" at temps above 1400 F. Sounds bad.
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VincentHill
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posted December 30, 2007 12:40 PM
It is Brass that makes the best seats. I was shown some Old Single Race engines there they cast the Aluminum around the Brass so that the seats and head insides where Brass Saying that, to me, Stainless would seem to be better because it will wear a lot better against any Abrasive
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APE Jay
Novice Class
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posted December 31, 2007 12:06 AM
Titanium is a soft material. That is why they coat it to keep the valve seat from hammering the valve face.
The reason they use them is that they are lighter than steel ( 56%)so they can run less spring pressure which frees up horsepower.
The new busa went from a double spring and steel valves, to single spring and Ti valves. As soon as you find it necessary to increase spring pressure, such as turbo / nitrous, applications the ti valves will probably have to be changed out.
All of the oversize seats we make are nickel bronze. This allows Ti valves to be run with elevated spring pressures.
As for the coatings, I know they are using Cassidium for Ti wrist pins. Don't know how it would hold up under the heat a valve is subjected to.
Jay
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GUNNER
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posted January 01, 2008 09:19 PM
For the life of me I don't know why Kawasaki used Ti on the exhaust and didn't use it on the intake of the ZX10.. WTF??
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tcchin
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posted January 01, 2008 10:24 PM
Cost.
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GUNNER
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posted January 02, 2008 07:47 AM
Yea but even at that. WHY? put them on the damn exhaust side ? Makes no sense at all when the intakes are always larger and heavier anyway.. They would gain more from the weight reduction if only one side could be done
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zrxdean
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posted January 02, 2008 12:09 PM
Just to annoy you. Ha ha, it worked.
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TRNorBRN6001
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posted January 02, 2008 03:33 PM
Thats too funny, but I hear ya!
Thank you very very much fellas.
Any more imput on longevity issues and/or Nos/Turbo applications would be great.
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GUNNER
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posted January 03, 2008 12:12 AM
quote:
Just to annoy you. Ha ha, it worked.
Hell did I date their mom or something 
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