Quote:
Originally Posted by Chris Uratchko
That's not accurate. The fastener is not the issue. The column of aluminum under the fastener is the weak link.
If you ever have a chance to do a pressure map on a deck(which everyone building engines should do) you might be surprised at how much a cylinder head bends when you torque the fasteners. And where clamp loads on the gasket surfaces actually occur. More load on the fastener does not equal more clamping force in most instances. Most castings I have tested are not able to withstand the torque that people try to apply with larger studs and higher loads. Instead the head deforms and bends and you have isolated clamping right under the fastener column, and nearly zero clamping force anywhere else..... due to the column compressing and not distributing load across the deck....
In other words, these types of scenarios are what are driving things like sealing rings.... improperly designed castings, and improper assembly methods.
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Exactly right! Everyone needs to absorb that. I'd also add that the "bridge strength" of the head between studs is a big deal too. Our billet funny car heads seal terrific across the whole gasket. No water jackets, approx 1" taller than a stock head and a minimum .25" wall around all studs makes it way stiffer than typical.
Eric
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