What are you guys using for exhaust valves?
My choice is typically Ferrea Super Alloy. I am going to cheat and paste some of their information here, after my response. I am not a mettalurgical engineer, so i wont pretend to be one. What I can offer, is experience in using many different brands under blown or nitrous applications. I have used 4 of the brands you mentioned, along with REV valves. My opinion of Manley has changed over that last few years, and I dont think their quality is what it once was. I have done a few sets of their Extreme Duty valves, and I know the boat guys use them also. I just have seen and heard things that dont give me a warm and fuzzy is all.Just my opinion. I am in a group of engine builders, and we have a private forum, and often discuss problems/issues etc. I think many agree with that thought.There is a builder/ cylinder head shop on this site, that may chime in with his feelings, as I know he uses Manley quite a bit. Most of the manufactures have a special hi temp alloy of some sort. My view is favorable of the Ferrea products, and I havent used them in a supercharger application, but many of the PBM type ( several suppliers have them) " Black Knight" valves, have been doing well. I have a set of DRCE Pro Stock heads here now, and although i am using Brodix valves to " size" things up, they will get Ferrea custom valves when ready. These will not be Ti valves either, based on some customer needs.Short answer, use one of the special hi temp alloys, and move forward. Certainly call the manufactures for more technical needs if that is required. ( BTW, I have absolutely seen thermal fatiguing of valves, and worked with Ferrea on one issue with a high nitrous loaded engine, and the "erosion" ( it was actually a thermal problem) of the valve heads. The original valve material was not up to the task.Very easy to see. I know this didnt " answer" your specific follow up question, but maybe helped with a thought process.
Here is some of the Ferrea information:
Proper material choice for the application is crucial to the valve performance and reliability. The extreme change
of temperature to a valve in the combustion chamber area (in excess of 1600ºF) and in the intake manifold area
(up to -25ºF), can cause “thermal fatigue”. The material’s ability to resist these drastic thermal variations is crucial
to the valve life. This is why Ferrea is constantly testing and evaluating new materials and processes to provide
the highest level of “fatigue resistance” in the industry. Here is the growing list of materials that we use in the
production of our valves:
SUPER FLO VS. FLO
This illustration shows our Super-Flo valves (often referred to
as under-cut or Neck-down), that actually reduces the stem
diameter in the port area. This increases flow over “straight”
stem diameter (Flo valves) considerably without adverse effect
on reliability.
To properly establish the amount of reduction in the stem,
several factors have to be considered, such as: original stem
diameter, valve head thickness and diameter, valve material,
engine application, etc. There is also extensive testing
conducted to reach the most efficient combination.
X3 Steel Alloy (Chromium/Silicon) Intake Valves
Y6 Steel Alloy (Chromium/Silicon) Heavy Duty Intake Valves
EV8 Stainless Steel (Chromium/Nickel) Racing Intake & Exhaust Valves
EV8-Z18 Stainless Steel (Chromium/Nickel) + Tungsten Racing Intake & Exhaust Valves
EV4-N12 Stainless Steel Hi-Temp Turbo Intake & Exhaust Valves
VV54/EV16 Stainless Steel Hi-Temp Racing Exhaust Valves
VV54/Nb/W (Nickel Base + Niobium + Tungsten) Racing Exhaust Valves
VV50 Stainless Steel Hi-Temp Racing Exhaust Valves
IN-751 Inconel Alloy 1.800 ºF Turbo Intake & Exhaust Valves
NICKELVAC N80A Super Alloy (Nickel Base) 1.850 ºF Racing Exhaust Valves
NIMONIC 90 Super Alloy (Nickel Base) 2.000 ºF Turbo Exhaust Valves
NICKELVAC 600 Super Alloy (Nickel/Chromium) 2.200 ºF Racing Exhaust Valves
NICKELVAC 800 Super Alloy (Nickel/Chromium) 2.400 ºF Racing Exhaust Valves (Funny Car/Top Fuel)
NIMONIC 263 Super Alloy (Nickel Base) 2600 ºF Turbo & Nitro Exhaust Valves
WASPALLOY Super Alloy (Nickel Base) 2700 ºF Turbo & Nitro Exhaust Valves
ASTELLOY 75 Super Alloy (Nickel Base) Turbo Exhaust Valves
PYROMET Super Alloy (Nickel Base) Turbo Exhaust Valves
PYROMET 31 V Super Alloy (Nickel Base) Turbo & Nitro Exhaust Valves
PYROMET CTX-909 Super Alloy (High Nickel-Low Expansion) Heavy Duty Turbo Applications
PYROMET A286 Super Alloy (High Nickel) Turbo Application - Sport Compact
NCF 3015 Super Alloy (Nickel+Chromium+Titanium) Turbo Racing Exhaust Valves
STELLITE (Chromium/Tungstem) Seat & Tips Applications
