X-Mozilla-Keys:
Archie wrote:
Gentlemen;
Instead of beating this thermal expansion to death, trying to
complicate and re-invent the wheel, this effort, and banter could
be directed to more important items.
I reiterate: Nascar, Nhra, Act, etc, etc, use head and stud bolting
of aluminum to cast iron with no problems. (some static
compression ratios are 16-17 to 1).
Of late, torque to yield fasteners provide improved clamping forces
on these dissimilar metals with no problems.
Archie
Yes but Archie racing engines have a life expectancy of three hours
and the heads are not six inches thick where the bolts go through.
Well maybe hemi heads are. Hemi's have a life expectancy of
five seconds. Heck they don't even use coolant.
If you lose all your coolant in a NASCAR race engine you are merely
out of the race. Cost of rebuilding the engine is of little concern.
Clamping forces are not the problem. The stock bolts are
good to 55 psi boost.
We are trying to get these rotor housings to survive an
inadvertent overheat to 300 to 400 degrees F as new rotor
housings are about $400 each. We would also like to do
it at low cost as there are 16 tension bolts and at
about $7 to $8 each at ARP the cost for bolts alone would
be about $112 to $128. If we can do it with 32 belleville
spring washers the cost should be under $15 or $20.
In fact I don't think we need that many as the housings only
shrink on the hot side.
If in fact the ARP torque to yield bolts work fine
we need to verify that without destroying good rotor
housings. There is another issue with a necked down bolts
and that is failure under resonent conditions. Solutions
in the past have been to coat them with RTV when installing
them to damp the vibrations. My suggestion is try one or
two in the engine on the cold side and check the torque
from time to time.
Paul Lamar
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