anybody upgrade your exhaust valves?
10-28-2004, 05:27 AM
#26
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exhaust temps/velocity
I've always been under the impression that exhaust gas temps/velocities drop in relation to the length of the exhaust manifold runners... perhaps not proportionately, but there is definitely a "longer = colder = slower" relationship that I have come across in various articles and discussions. Was this principle much of a concern during the design of your exhaust manifold?
I'm not trying to "hate." In fact, it looks very pretty, and I'm looking forward to seeing the results of your tuning. It's just that there are a lot of conflicting opinions when it comes to this sort of stuff, and I'm trying to sort out the science from the speculation.
I'm not trying to "hate." In fact, it looks very pretty, and I'm looking forward to seeing the results of your tuning. It's just that there are a lot of conflicting opinions when it comes to this sort of stuff, and I'm trying to sort out the science from the speculation.
10-28-2004, 04:29 PM
#29
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A word on sodium metal (FUN Stuff!)
If you cut your valve stems in half, be ware-y of strange stuff--
Sodium metal reacts - violently - with water.
Touch it - and it will boil the moisture on your fingertips. While your fingertips are attached to your fingers. Into your fingers. All of the way. (Are we clear?)
Now - knowing that --
Sodium metal is a putty like substance. While it is stored in oil - I recommend mineral oil as it is clear, (or olive oil if from an Italian valve) - it is perfectly safe. Drop a crumb into a wet laundry tub, & it will skit about until consumed. Great fun!
Drop a blob in a plastic container of water -RUN! (It helps when covered in the oil! Gives you a few more steps!)
Need I say more?
Sodium metal reacts - violently - with water.
Touch it - and it will boil the moisture on your fingertips. While your fingertips are attached to your fingers. Into your fingers. All of the way. (Are we clear?)
Now - knowing that --
Sodium metal is a putty like substance. While it is stored in oil - I recommend mineral oil as it is clear, (or olive oil if from an Italian valve) - it is perfectly safe. Drop a crumb into a wet laundry tub, & it will skit about until consumed. Great fun!
Drop a blob in a plastic container of water -RUN! (It helps when covered in the oil! Gives you a few more steps!)
Need I say more?
10-31-2004, 10:52 AM
#30
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Re: anybody upgrade your exhaust valves?
Ferrea has/makes a "special alloy" supper 900 exhaust valve that can be had in a 28 or 29mm size. They are pretty pricy however. I doubt you could or should try a 30mm valve. Going +1 will, I'm informed, require new valve seats. Mechanics opinons have varied on the wisdom of doing regular, much less oversized valve seats in the AAN head. Be aware that you are playing with a "ratio" between exhaust and intake valve sizing. Also with regard to "stem" shape, keep in mind the valves are handling different flow directions. Last, keep in mind while you are changing valve sizes &/or material, you want to give some consideration to valve WEIGHT. From what I recall, a stock 28mm exhaust valve weighs @ 46 grams, ... I think. The Ferrara 29mm Special Alloy version comes in at 51 grams ~ but boy can it (according to Ferrea) handle temperature. http://www.ferrea.com/
HTH
HTH
HTH
HTH