Ok, first off, only do parts that are going to be strained, and parts that are cast steel or aluminum. Forged parts won't benefit, and can actually be weakened since they're made differently. As for doing your header, it won't do anything but waste your time.

Save cryo treating for things like the crank, rods, camshaft, lifters. You can do the block if you really want, but you run the risk of having the sleeves fall out of it since aluminum and steel cool at different rates. I also wouldn't suggest doing the whole head, since the valve guides can also fall out.

Also, under no conditions subject your bearings to cryo treatment. Bolts aren't going to get much stronger than grade 8 hardware either, I wouldn't bother.

 

well that was educational! thanks a ton! im glad i have all that to think about now. so why is it horrible to do the bearings? and you would do the rods, right? do you think it really worth it, cuz im thinking that involves taking the pistons out too, and redoing the rings, which isnt a whole lot of fun. crank will get it, cams will get it, lifters will get it, and an extra spare set of rods. thanks for the help

 

The bearings are multi-metallic, consisting of tin, copper, lead, and some other alloys, so unless you want to unbond them, don't super-freeze 'em.

Rods, as long as they're not billet or forged, are perfect candidates for cryo treating. Transmission gears are also perfect candidates.

 

ok, heres another for ya, is it worth it to take the rods out? cuz that means pistons come out, right? and redoing rings isnt the easiest thing. i have an extra set of rods, im thinking ill do those for sure. but do you think its worth it to take the ones out of the block?

 

If you have the engine tore down that far, don't cheap out by skimping a ring job.

 

thing is, theyre all brand new anyway. the engine was just basically rebuilt. however, the oil pump didnt work correctly and died, but as soon as pressure was lost, the car was turned off and parked, so nothing more than bearings/crank. everything else is fine. and while on the topic of what to do, how about brake rotors? think those could benefit? again, thanks

 

i think cryo treatment is more popular among tranny internals than engines...at least on our level, since we arent building a $15,000 race engine.

my friend has an 04 STI and he wants to get hit tranny internals treated.

as far as the rotors...its normally not worth it but throw those bitches in there if its free.

~kris