I melted the #1 piston in my 408 (4.030" bore). I doubt a .005" over bore/hone will clean it up. Originally I thought, no big deal, punch it to 4.060", throw new pistons in it and call it good, but multiple reliable people have said that is too much to take off. I could definitely see that being the case with an aluminum block (LS1/6/2) but I didn't think the iron blocks had sleves (could be my ignorance) so it seems to me that going to a 4.060" bore would be similar to an LS3 which has a 4.065" bore and thick enough sleves to do that. Keep in mind the motor will be making ~1000 at the wheels on kill.

 

Went through the same thing recently. Sonic testing showed ours was good to .085" overbore and if you look over on YellowBullet, some builders have said that about 1 in 5 will actually go .125" over but that would be in a non p/a application. Just sonic test it and see where you're at but blocks are pretty cheap. Can you not go .040" over and stay with a shelf piston or is there something else you are trying to accomplish?

 

Sonic testing is the way to go. I don't know how the block will hold up to 1000rwhp at a .060" overbore however.

At this point, if you're shooting for 1000rwhp, I'd at least consider an LSX block and 6-bolt heads.

 

Not looking to max it out, I just want the smallest ~-30cc piston I can put in there without having to spend big bucks for something custom. Wiseco doesn't seem to make a 4.040", just 4.030, 4.035, and 4.070. Would like to stick with Wiseco but open to other options if it makes piston selection easier. It would also be easy enough to pick up another LQ block.

 

So what are they looking for specifically when they sonic test it?

Whats funny is I already have 6 bolt All Pros, but I'm just not willing to spend the $ on an LSX right now. Was really hoping to clean this block up and throw new pistons in it and be done.

 

The sonic test is just to see if the block will hold together if you bore it to a certain point. Since it's a mass produced block, the QC varies block to block on the wall thickness. Just get it tested to see if you can take it out.

Also, Wiseco does custom pistons. Might be better suited for what you want. Price is a bit more - maybe $150 more for the set. Diamond does as well and it'd be about $200 more for the set vs Wiseco shelf. Unless you go for some options like coatings, piston squirters, etc, then it'd be more.

 

Well I took a closer look at the block and it is sleeved, originally I didn't think the iron blocks were. So that answers why it can't be bored to 4.070" safely. Engine builder says he thinks the block will clean up at .035" over. If so that is good news. Wiseco makes an off the shelf piston in 4.035" that will put me back at ~9.9:1.

 

I didn't think so either, certainly not factory if that block is indeed sleeved.

 

Fairly certain it was a virgin block when I got it, it was priced accordingly. You can see the sleeves in this pic. Seems like taking another .020" off of each side would make them really thin.