Find the right price point on some lightweight valves, and I would be up for a set in the screamer I am building. I have been considering titanium myself. I know the benefits, even tho this forum seems close minded to what the race world knows.
Titanium valves will make more power than stainless valves period. It is for the same reason shim under buckets make more power. If I had the money to do it, I would already have them in my motor.
Getting the valves will not be a problem either. It is no different than specing a piston for your application. You just have to be willing to pay the price. I recall it being like 3 or more times the price of stainless. I can't remember.
I will warn however that they are a little bit more fragile than stainless. Nitrous guys are often advised to run them on the intake side only. I have no idea if that would be the case with other forced induction methods. You may want to consult with the manufacturer and tell them what kind of set up and racing you will do.
If I recall, they need to be replaced more often, and maybe the reason alot of forced induction guys do not use them. I can not recall all of the facts regarding them. It was a long time ago when I considered using them in my small block motor.
Yeah there are two potential areas of improvement a more heat resistant valve material and conducting more heat away from the valve. Copper beryllium vavle guides and seats are much better heat conductors than iron, that is why they are used for titanium valves(which dissipate heat very poorly but are light and strong). The only problem is copper beryllium is much softer than iron and so may not last as long. I am not sure but some of the newer sintered metal valve seats may transfer heat better than the cast iron seats that I think are standard on miata heads.
As for valves I looked at different exhaust valve materials-supertech will make you inconel valves for about $30 per valve but they have a minimum run of 50 per size.
Ferrea was a bit more expensive.
Manley I think has their extreme duty valves in inconel. Their severe duty valves have more heat resistance than the typical 21-4N stainless that supertech uses.
Flyin miata sells inconel valves that are relatively cheap now-I don't know who makes them.
Note: I have burned exhaust valves twice with FM built motors These showed up just after I last rebuilt my motor. I suspect exhaust valves are the weak link in my motor now.
In my opinion the standard replacement valves Spartech etc. are inadequate for track driven cars over 300hp. The picture on FM’s site of a bad exhaust valve is of the fancy black nitrided stainless valve with burned pits in the seat. I actually think stock valves might be better than these.
I have a set of 323 GTR sodium filled valves but they are not oversized and I haven’t put them in anything yet. I bet they would be as good as Inconel.
only for 1.8L GTR motor, dont know if they swap in the 1.6
They Won't fit a 1.6l
I will say I've melted down forged pistons in a GTR powered GTX a couple times now and the exhaust valves stayed fine. Don’t ask me why the original owner ditched the GTR pistons. The GTR pistons are the only ones that were actually designed to utilize the oil squirters as they had an internal galley that channeled the oil squirter oil through the piston to pull heat from the upper ring land area instead of just the bottom of the piston. The GTR pistons were actually two materials as well. The ring land portion was cast Iron and somewhat impervious to wear or extreme abuse.