nimonic and 214 stainless steel valves

[mirpur]

What's the advantage of nimonic valves in an let exhaust side in comparison to 214 stainless steel valves ,power trying to achieve around 500bhp
Also how good are sterile seated valves in comparison to nimonic and 214 stainless

[Davey j]

Nimonic - Wikipedia, the free encyclopedia

Wiki can be unreliable but it's a source at least..............................

[mirpur]

Is it a must in a high powered let how much better are they than stainless,what temps can the exhaust gases on an let get to as stainless I think can handle around 750 degrees max

[bigron1988]

Jut having some of these fitted to my let now, as I got told that Stainless won't last with the heat

[mirpur]

What about stellite will they take the heat

[Gordo]

Someone correct me if I'm wrong, but as I understand it, Stellite was used as a facing for valves to reduce face wear when lubricating lead compounds were removed from fuel. It's also used as a seat material due to it's hardness and durability.
In the head, the seat has little by way of combustion heat to endure and is well cooled by the surrounding head material whereas the valve head (both the front and the rear of the valve head) have to withstand very high temperatures and effectively run red hot with the only cooling effectively being through the seat and the guide.
The very high head temperature of the exhaust valve, and the associated expansion, may cause the two seat faces to move relative to each other, possibly rendering a careful lap in redundant - I don't recall a definitive answer, either way.

[Rs1]

Nimonic can handle the abuse in terms of heat
How hot are you running though? If you dont need them its just something on the spec list and a wad of cash out your pocket

ALS use is a likly scenario to build excess heat....although imo you'd be on the wrong valves using nimonic with antilag that is of any use.

Vmax events perhaps? Where else do you get chance to holding a 500hp LET WOT for more than..... 15 seconds or so?

[mirpur]

I dont know how hot im running and your right about a wad of cash if i can get away with stainless valves id use them but dont want to keep taking the head off to do things
how would you build enough heat to damage a stainless valve, how long would you need to be on full throttle to cause heat damage to a valve

[Rs1]

How long is a piece of string?

Pretty sure steveboyslim can give you a good idea of differance between the steel and n80 in terms of the.....integrity at x temp. I know he can get his hands on both should you require them
Cant say ive heard of many failures of steels but it totally application dependent. If your not doing any testing then its best to air on the side of caution and 'over spec' your build imo.

[mirpur]

the valves i took out were rec 458 wasted stem 33mm and standard on the other side