This is the engine im thinking about going with....I have a 08 STS twin turbo kit already installed and blew the LS3 a few months ago... its an A6 with 2:56 rear and I will be installing a 2800 stall and headers the same time as the engine swap. I want the car to easily run in the 10's.... looking for opinions on if that's the route other guys would take.... any replies would be great.

Summit: $8100 shipped

For builders who want to stretch the performance of a turbocharged or supercharged combination, we've got just the foundation you need. These Chevrolet Performance LSX 376-B15/450 HP crate engines feature a durable, all-forged rotating assembly to handle up to 15 lbs. of boost! Chevrolet Performance's engineers started with the tough LSX steel Bowtie standard-deck block and added a forged steel crankshaft, forged connecting rods, and forged pistons. Then they topped off the short-block assembly with high-flow, rectangular-port LSX LS3 6-bolt aluminum heads for supercharged and turbocharged combinations. The engines are delivered without an intake manifold and other accessories, allowing you to tailor the induction system and other features to suit the forced-induction setup of your choice. Due to the number of application variations, the engines are supplied with a dust shield instead of an oil pan, Any LS-style oil pan and pickup that will fit your chassis can be used. Also, the LSX376 valve covers do not include provisions for mounting the ignition coil brackets. Aftermarket or custom relocation brackets must be used.

Chevrolet Performance LSX 376-B15/450 HP crate engines specifications include:

* Power: 450 HP @ 5,900 rpm, 444 ft.-lbs. of torque @ 4,600 rpm (horsepower and torque ratings were derived by GM Engineering using a normally aspirated LSX376 with LS3 EFI--your power numbers may vary, based on induction system and componentry)
* Displacement: 376 c.i.d., 6.2L
* Bore x stroke: 4.060 in. x 3.620 in.
* Compression ratio: 9.0:1
* Recommended fuel: 87 Octane
* Block: LSX cast iron with 6-bolt cross-bolted main caps
* Crankshaft: forged 4340 steel, LSX 8-bolt flange
* Connecting rods: forged powdered metal steel
* Pistons: forged aluminum
* Camshaft: steel hydraulic roller tappet
* Cam lift: .560 in. intake/.555 in. exhaust
* Cam duration @ .050 in.: 210 deg. intake/230 deg. exhaust
* Lobe separation: 121
* Cylinder heads: aluminum LS3 rectangular-style ports
* Combustion chamber: 68cc

 

Wouldn't even consider it. You can get a much nicer, better motor for less money than the GMPP motors. A nice forged ls3 setup with much nicer parts can be had for WAY less money.

No need for iron block for what you want, it will just be a big downside.
That motor runs a cheap rod.
Runs a lower grade alloy piston.
Probably want to swap the cam out for something better for a turbo.
8 bolt flywheel flange means you need a new flex plate/etc for your auto.

I would send your ls3 block out, get it rebuilt with nice parts and go from there.

 

Take the block out of the equation and for that money you can build a hell of a lot more motor...

Reuse your stock block if its not damaged, have the mains pinned and use main studs.
Callies Compstar Crank
Callies Compstar Rods
(or use K1/Wiseco instead of callies)
Wiseco or Diamond pistons (your choice)
LSA Heads with BTR spring kit and upgrade to LS3 hollow stem intake valves and ferrea Inconel exhaust valves. (70cc as cast, nicest chambers ive ever seen on a production head, better alloy and gusseted rocker bosses)
Head studs...

Engine will handle 1000whp all day with a good tune. Tune is key in any build.

 

Inconel valves? Those sound super heavy. Probably have to limit it to 5k rpm.

 

Ive had no issue spinning the Ferrrea Super Alloy (Inconel or like material) to 7000...
We had a valve fail in the past due to the heat generated by road racing a 1000whp F/I car, no issues since swapping to these. We also run their competition plus hollow stems. I wont do a F/I build without them anymore, its cheap piece of mind and they have proven to hold up great.

Ferrea P/N F1893P

 

That was sarcasm. If it was in the z06 forum they would flip, because you have to run stock or near stock weight or suffer death from bounce.

 

Wasn't sure if you were screwin with me or not...

Regardless, failed valves due to heat are not pretty... For a couple hundred bucks, they are worth the upgrade weather you need them or not.

 

Would definitely run Inconel on a turbo build.

I agree with everything you said, stock ls3 block, compstar/wiseco, LSA heads with nice parts, and you have a solid 800-1000hp motor that will be far superior to the LSX376 motor.

 

No way. As mentioned above, have a motor built for much cheaper that can handle big power.

 

Hmmm. Inconnel

Just need someone to build a turbo kit with the stuff now.