titanium valves

[toad490]

Has anybody used titanium valves with a 7mm (.275) stem in a street /strip motor? I'm worried about longevity eh. Also can titanium intake valves be cut down and used as exhausts?

[TrashedCharger]

I would not suggest cutting down titanium valves. They affix tooling to those valves to cut them specificly to that size. If you cut them down (if you can find a shop with a diamond cutting setup) you can run the risk of cutting past the hardened area of the lap seat. If you have them, USE THEM on your intake! Go buy a set of matched exhausts (get your seats hardened) and you'll have the best set of valves money can buy!

The amount of carbon in titanium is immense compared to even high nickel stainless steel. You'll never hurt those valves. Not to mention the amount of weight in motion has to be cut in half compared to a good stainless valve. I'd rollerize your heads and cam with that setup and those valves would be killer in a 7500+rpm engine! Just make sure you have the head/ block/ crank to handle it!

[sanborn]

Titanium valves are a "application specific" valve. They are used in high RPM applications. They can be machined very easily, they arn't hard and can be cut down in head diameter. Don't try to cut the stems down.

I would not use them for a street application- under any condition!

Why? Our experience is they don't retain their seat grind as well as steel/stainless. And, under extreme heat conditions, the titanium exhaust valves can soften and fail quickly. Titanium does tend to be cycle specific(meaning they can break quickly without deforming).

I'd use a good stainless valve(like Manley "Severe Duty"). They work well, will live a long life and are easy to handle up to 8400-8500 RPM without float.

[toad490]

I was going to cut down the lenght and use lash caps. Why would they use them in all top race engines NASCAR CART ECT if they're prone to faliure? The SR 71 spy plane is completly made of titanium, it was the only metal that would stand up to the heat and stress. The plane gains almost 2 feet in lenght from the heat at the speeds they flew. I thought this was the tuffest stuff goin eh.

[fastmopars .inc]

well for starters, for it's weight, titanium is stronger than most metals.
tungsten is far stronger.

the exhaust valve runs at a much hotter temperature than the intake (while it's in motion) so they usually are required to be made stronger, whether filling them with sodium or using a stronger material altogether.

and when you ask a question on a message board, some of the answers will be a surprise to you. this is probably why you asked the question, to gain more information, and everyone has a different experience with one product than the other. i doubt anyone is feeding you a story, they are only going from their own experiences. weigh their application against your own and see whos opinion most matches your situation.

an exhaust valve goes through 1000000 times the stresses that the sr-71 has to withstand, without leaking 2 gallons of fuel a second when it's not at operating temperature.

[toad490]

I apoligize if I came across like I thought you weren't being anything but straight with me. When I asked those questions I wasn't trying to be argumentive, I honestly just wanted to know the why.

[MoparMarcIdaho]

of titanium valves compared to stainless?I usually try to run Manley stainless in everything,including my harley.

[sanborn]

Titanium valves are very light, very tough. They are used extensively in high RPM applications. But, they are replaced frequently.

For example, this past weekend there were 43 Nascar cup engines that ran, 43 Busch cars and 36 Trucks. This week there is probably 30+ sets of titanium valves on the used market. They are changed that frequently. Most are absorbed by 2d, 3d and 4th tier race engine builders. They will give good service for the weekly racer, but at the professional(high $$$) level, the engine builders can't afford the risk.

For a drag only engine, they will give years of service. But, on the street, with many miles of driving---I wouldn't want them.

We use them in all our oval track engines. But, they need to "freshened" about every 1500 laps. They wear out before the bearings, rings, etc. do.

[biggerhammer]

sanborn is correct about the use for titanium valves, I wouldn't recommend them for a street engine at all.

[toad490]

OK..I give. I have a extra set of heads, I'll use the valves in that set and and swap them when I go the strip. Thanks all.

[RogerH]

Originally posted by toad490
Why would they use them in all top race engines NASCAR CART ECT if they're prone to faliure? The SR 71 spy plane is completly made of titanium, it was the only metal that would stand up to the heat and stress. The plane gains almost 2 feet in lenght from the heat at the speeds they flew. I thought this was the tuffest stuff goin eh.

They are still prone to fail, even in CART. I used to work for Honda on the CART engine program. For a while we used Ti valves only on the intake and steel on the exhaust side. The rocker side of the valve was friction welded to a steel end. They still had problems occasionally with the Ti valves cracking and braking. But, when you consider that the average rebuild on the CART engine is 350 miles, and then the valves are replaced! Actually the whole valve train was thrown away. Eventually they played with Ti exhaust valves, but mostly for super speedway use only.

Of course, in professionaly racing, money is no object, and winning is everything.

Actually, titanium is not the tuffest stuff going, Beryllium is. Its the strongest metal for its weight, the problem is that its toxic to machine it. Forumla 1 used it for a while, but asked them to bad its use. It has to be machined in a clean room type environment to protect the machinist from the toxic fumes/particles. Not only that, but they were using Beryllium in brake parts and were worried about the dust causing toxic posioning of the crew members, and that with the engine parts they used it on, they would get particles out of the exhaust and emit toxic exhaust to everyone in attendance.

[toad490]

game.....set......match!