Stress relieved blocks

[Photonfanatic]

I saw some show on tv where they "stress relieve" then engine blocks as part of their rebuilding process. They set it on some kind of table that vibrates and matches the exact... i don't know... harmonic resonance that the block has. Or something. I forgot what they said. Anyway, you get the idea. Somehow this stress relieves a bare block. I never knew metal had "stress" in it. How does this help? What's it good for?

 

[RockstarMentality]

'scribed

 

[auto_x5.0]

I've never heard of this, if it's cheap and not a joke I got a bare 351w block I can test it on lol

 

[vermilion]

also de-burring a block serves the same purpose. it relieves potential for stress cracking.

 

[SRT Handz]

You saw this on horsepower TV. I saw the same thing. I would think that it does something because they were talking about doing it on a race motor. Pretty cool process.

 

[vermilion]

some machinist call it jeweling.

 

[Photonfanatic]

So what does it actually do? Someone said prevent stress cracks? What stress is inside the block and how did it get there? Weird.

 

[vermilion]

during the casting process everything is not equal. there is excess casting, welding flash and etc. this leaves jagged edges in crucial areas. under engine torquing and harmonic resonance these flaws induce cracking of those jagged edges.... think of a bridge swaying constantly. after years of torquing and swaying it starts to crack at the base or high stress joints... deburring an engine block minimizes these same affects.

 

[Photonfanatic]

Ok but puting it on that table thing is going to... knock off all those burrs somehow? Seems like that thing would really have to get moving to do that.

 

[vermilion]

its used in seasoning cast iron blocks. heating up and cooling in a few cycles then using that method strengthens the block.

 

[Photonfanatic]

So really its doing something on the molecular level...

I'm trying to understand what's going on but failing lol

 

[CC'S95GT]

There is a process used in aviation called shot peening.
Basically we shoot steel shot at the part to relieve the internal stresses which reduces the possibilities of cracking or failure. It kinda realigns the molucules to make the part stronger.

 

[mikey94gt]

What he said. It's like taking a random pile of 2x4's and assembling thm into a wall. Much stronger (and a bit dramatic) but you get the idea.

 

[Photonfanatic]

Ok so there is something about older blocks that makes them already stress relieved? Some show on TV was saying their 220K miles block was going to be good after it got back from the machine shop because after all those miles, its going to be stress relieved now.

 

[CC'S95GT]

I would think only the race or high permance blocks get stress relieved.