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[OB_THE MOTORHEAD]

no the regular cams work harden.if you surface harden billets they would be better.i hate work hardening over surface hardening.prostocks cannot let there motors run 20 min to work harden thats one reason.

[This message has been edited by THE MOTORHEAD (edited 12 June 2000).]

 

[OB_GSXRTURBO1]

Great thread guys. DanaT, the strength to weight ratio concerning rods seems like just a part of the equation, what about the effect of cyclic loads? It seems that's why aluminum is such a good choice in top fuelers (read forgiving). I'm certainly no expert on any of this, so I'd appreciate any comments.

 

[OB_THE MOTORHEAD]

ok dayna caugh up some of those high quality metals we discussed way back when discussing cranks i know this is clearly your domain!!!!!!En-30 is what i enquired to bigabusa on obtaining bar stock.so what you got metalman?

 

[OB_DanaT]

What you are thinking of as "forgiving" is not the cyclic loading. It is the modulus of elasitcy. That is, the amount the part can deform elestically (think of elestci as a rubber band and returns to the original shape). Once this load is exceeded the part has deformed permantly (changed dimensions this is typically taken in the US as great than 0.2%)but is still a sound part.

Top fuel relies on the softness and the resultant damping effects of such a material to quell the harsh impact loading of the con rods when using nitro methane (this is about my limit of knowledge of how a nitro engine works).

To sum this up somehow, you basically want to select a material that gives the most favorable properties while minimizing the unfavorable properties. This is very specific to operating environments,ect.

-Dana

 

[OB_DanaT]

TMH,

There are some specialty alloys that are used in F-22 that would perform very well. I have been trying to get some but as of right now I haven't had much luck (of coarse I can get it in a few days if I buy 5000lbs@$15 a lb).

I am still trying to convince the guy to give me some "samples". I need to remind him.

I have more info at home. I will email ya with more info.

-Dana

 

[OB_Jay]

In order to really work harden the surface, you would have to run the cams dry. Remember, there is an oil shield between the lobe and bucket. There might be a slight work hardening in a broken in cam, but it would not be as hard or as deep as hardfaced cams. If you took a well broken in set of cams and put them in a pro stock motor with 135 lbs seat pressure, and close to 300 over the nose, you would kill them in a couple of passes.

Jay

 

[OB_DanaT]

TMH,

You are correct that the cams will work harden. The problem is you shouldn't expect more that about 5%-10% increase in hardness by work hardening.

What Jay has said is correct about surface harening. The biggest problem is that with surface hardening, you are welding dissimilar metals together. Typically face hardening is done in two steps. The first step deposits the buildup material. This material should be selcted to allow dillution with the base metal that will minimize problems with dissimilar metal welding. The final layer is a hard facing material. Depending upon the class of material, steels contain tungsten ,chromium, nickel, moly or other alloying additions.

What this attempts to solve is that you have a base metal camshaft that is not briitle but has faces that are extermely hard (read brittle). The cams themselves could not be made of thsi hard facing material as it is too brittle and would self destruct if nicked or any thing else (try dropping a mill bit on a cement floor for a demostration...but please wear safety glasses).

What they are trying to solve is that the less than optimum material (read cheap) was used when making the original cam shaft.

There are many better ways than surface welding to achieve the optimum comination of properties in the camshaft material but they are not cheap.

Anyone interested in con ords made from materials that are better (better strength to weight ratio) than ti?? It can be done, but is not cheap.

Just something to ponder.

-Dana