Plenty of guys run moly rings under boosted applications and have no problems. I think several of the guys in here are with their boost F bodies.. perhaps they'll chime in.

 

I use moly rings in boosted apps and never have problems.

 

D@mnit. I never thought these little issues would be so tough to determine. It would be much easier if there was just one clear way to go.

Will regular moly rings have a problem standing up to 15-20# of boost?

Also, since I have to get custom pistons anyway and the block is in good condition, should I only over-bore the cylinders only .010 or .020 to keep a little more strength in the block, and possibly be able to bore it out some more in case of a future re-rebuild?

 

I would only bore it as little as possible to get the bores pointed in the right direction and a good hone in it. You're not boring the motor for the huuuuge displacement increase and the gigantic bump in power

 

I get a little nervous when you start talking about 20psi. I am forgetting if it was mentioned, but I assume as a DD you are going to be running pump gas? A SBC, 20psi, pump gas, and longevity are not in the cards. If I was builiding a boosted LT1 for performance and longevity I would not plan on using more than 12psi. Get good heads, the best pistons you can, run a low CR, an intercooler and water injection.

There are some potential advantages to keeping the overbore to a minimum. You need to get it apart and inspect/measue the existing bores before you can decide this. Unfortunately, you are talking a custom ppiston for a 10 or 20 over setup. Not a huge deal, but it does add $100-200 to the cost and may limit your ring choices. May also take a few weeks, or longer to get depending on the time of year.

There is no "formula" for this unless you want to copy a sucessful setup. Even then, there are lots of BS'ers here on the web so you need to be careful who you listen to. I don't recall if you mentioned your budget or how much you are doing yourself, but another option is get a pro involved. This can be costly or cost effective depending on where you are coming from and how you are looking at it. s a rule of thumb though, once you take an LT1 past ~600rwhp you are talking about a motor with very compromised longevity even with the best of parts and assembly.

Rich

 

20PSI would be VERY rare and on race gas. On the street, it would be maxed out at about 15PSI. This is all going with 8.5:1 compression, the Lunati/JE assembly etc.

I have to get a custom piston anyway because I am going with a 3.48 stroke/5.7 combo with a -31cc dish. However, if that will make the rings more difficult to source, I may just stick with a .030 over setup.

The heads are done.

I'd like to hear more opinions on whether to go with moly or Hellfire rings.