[Brucelee]

Posted by NITRO on July 03, 1998 at 09:24:41:

In reading your question, you have answered it with your research.


Regarding friction and wear, once again, you answered the question. If pistons travel at higher speed/ crank revolution, the amount of wear is greater. The anti friction composites we're now using help some, but T.O.O. also has another saying: Everything mechanical will eventually wear out and break.


The most common rod failures we've experienced over the years have always taken place on the "overlap" cycle, where the piston is traveling up at high velocities, with no compression up-top, and when the rod tries to slow the piston as it nears TDC, the rod goes, the piston pin can go, and the pin will sometimes pull the bosses out of the piston, or all of the above.


You're (simply) dealing with Mass x Velocity (squared). Now, examine the figures. Both mass and velocity are the players, but wich one is squared? = Velocity.
Regardless of rod ratio or any other player, the greater the RPM the higher the velocities, which = "ruined peoples motors".
What you like (regarding high rpm power), and what your engine likes are two different things.

If you ask any engine in the world if it enjoys running at high rpm = max. Q or stress, everyone of them will tell you they don't like it, unless one has a death wish or something.

T.O.O.'ll probably be around to better answer your question, but I gaurantee that he'll touch on the same items, and he talks to engines as well, that's how he makes them do what he wants, although he does write their genetic codes in the pre-build engineering.



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RPM's are nice...they are our friend

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Posted by 82'Rolla on July 03, 1998 at 06:21:24:

I love the sound of a high revver as well. Unfortunately to make your engine do this, it must be very well guarded against the added stress.


"*Maximum piston acceleration is approximately 8,000g which
puts a load of over 3 tons on each connecting rod."

This is where a lot of the damage comes from, and it increases non-linearly, not sure if it's exponential, plus the fact that the piston actually travels further. The stresses that your engine endures by raising the rpm's by 1000rpms is much worse than increasing boost by 10psi.


I suppose if you start out with the intentions of building a high revver, and compensate accordingly, it can be reliably done, but it sure will get expensive...Carillo rods ain't cheap.

I think it was Louis (deVirgilio sp?)from honda-perf who was also looking at this at some time, and noted the differences in the internal construction of the engines in relation to it's revability.Posted some nice articles, I think I still have them.

Ted