Maybe im just being overly cautious but has anyone had any problems hanging a heavy turbo header and turbo off of an aluminum head with the standard SBC exhaust flange bolt pattern? Didnt know if the heads would strip out or ?

 

we did tensile testing on 1/4" aluminum plates with 1/4-20 threads in college. It took over 4500lbs to strip the threads. So if you get some longer header bolts (I use 1" bolts through a 3/8" flange = 5/8" of thread engagement) the bolt head will most likely break off before the threads strip out. I have heard of a rule of thumb to go by: thread the bolt in to a depth equal to the diameter of the bolt. In my case its threaded more, 5/8" of thread on a 3/8" diameter bolt.

 

So its not really much of a problem at all then haha.

 

you get full strength in steel with 3 full threads engaged, in aluminum with 5.

WRT to the actual question, tensile strength isn’t the only question, engines vibrate and that vibration causes the weight hanging off the fastener to act like a hammer, slowly hammering out and loosening the threads. OTOH, it’s probably not a significant problem till the fastener comes loose allowing for a moment arm to get a bit of a swing at the job…