LS1, 2, 3 for road racing?

So my LS1 has unfavorable leakdowns. I've found a nice set of 243 heads I'm going to use and now I'm on the hunt for a short block.

Several vendors have nice, built short blocks that I'm considering. The question is, LS1, 2, or 3?

My normal knee jerk reaction is to go with the biggest displacement so I can make MOAR POWA.

However, I really want something with the best longevity/reliability possible. I'm not terribly concerned with the oil issues I've heard about the LS3 because I'm running a custom baffled oil pan, but is there anything else I need to think about?

From my understanding, the oil issues aren't in the pan, they're in the heads.

Says the guy who just pulled an L33 out to replace with an LS3...

The heads get some carbon galling on the valve guides, but check the oil control rings. I have found that the OE style ring is woefully inadequate and the best bet is a set of replacement rings and replace the valve guides with good quality units if you are having a leakdown issue.

Aren't the cathedral port heads intended only for the smaller-cube LS engines (346 and below)? Are you giving up power putting them on one of the bigger engines?

I have no personal knowledge of this, but recently read a thread about it on another forum:

http://www.miataturbo.net/race-prep-75/track-lsx-crew-has-anyone-had-one-grenade-68065/

I would keep cathedral ports to 6.0L or less, but it also depends on the type of racing. Personally, I would sell the 243s and apply the money to a good longblock if you're going bigger cubes

I think the BIG thing is to know the budget. I see 5.3L iron truck engines go for $750, but an LS3 brings big bucks.

I don't need the whole motor, just the short block. I'll be buying a new built short block, so it won't have factory rings/pistons in it. From what I understand, the 243 heads are still the best flowing heads and will work find on a LS3. Plus my FAST intake manifold is for cathedral heads.

In reply to docwyte: The 243 heads are about the best of the cathedral port heads from what I understand. But if you're getting an LS3 with more displacement, the newer rectangle port heads will outflow any of the cathedral port heads by a fair amount.

codrus wrote: I have no personal knowledge of this, but recently read a thread about it on another forum: http://www.miataturbo.net/race-prep-75/track-lsx-crew-has-anyone-had-one-grenade-68065/

Catastrophic blam-ification is not uncommon.

I think the issues have been tied down to valve float, especially if you tap the rev limiter, leading to a valve-piston handshake and you wind up with the leftover end of the rod blowing the side of the block out. It's usually pretty spectacular.

So, er, get good valvesprings, and the rev limiter isn't cruise control.

Much better discussions on the Corvette forums. Pay attention to Chris Ingle.

http://forums.corvetteforum.com/autocrossing-and-roadracing/2216993-ls3-oiling-problems-dry-sumps-legal-in-scca.html