I've been thinking about building a new engine for my procharged c5z and I've come across a short block that seems like a wonderful deal but I'd like some insight from more experienced builders. Compression ratio is perfect for my goals and it's forged.

https://www.summitracing.com/parts/hpe-sp68/make/chevrolet

 

Have one custom made to your EXACT needs....

TSP 376 C.I.D. L92/LS3 Short-Block (texas-speed.com)


What heads/cam/intake do you plan to run on this LS3 short block?
A short block is NOT where you want to cut corners or try to save a little bit on money! It's going to be expensive no matter who you choose.

 

The plan is factory ls3 top end and a BTR stage 3 blower cam.

 

the bigger bore big displacement stuff is expensive, and meanwhile people throw away the 4.8 and 5.3 stuff that makes beautiful power.

I spend most of my hard earned $$ on the turbos and blowers, but there need not be a 6000+ $ solution depending on your goals

for example

4.8 bored. 020 over, gen 4 rods with good bolts, stock std crank. This combo will hold 900+ all day with decent cathedral port heads, and I build the short block for just over 1200 buying one piston, bearings, rings and balance

assembled short block ready to rock. It can be done if you scrounge. The "truck bombers" who mud bog the LS engines go through them like candy. Lots of cheap spare parts if you aren't allergic to iron

I started snagging the 5.3 gen 4 alum blocks which are a very strong platform to build on. I got the block gratis, bought a crate engine for 400, sold the heads next day for 400

folks throw this stuff away if you look for it

LS3 and LS2 are great blocks to start with, but not at those "corvette tax" prices. I've spent the big $$ only to go slower and learn from those that run the stock stuff and "lightly upgraded" LS engines pretty hard.

1000 HP is nothing for these truck bombs that go for cheap and run very hard indeed.

 

You can have your LS6 done
Your block and crank, new Forges pistons, good cam, massage your heads add good parts to them, stud motor and you'll be hitting 700whp plus with no issues and cheap

 

the 03 and up ls6 block is pretty strong. If you can stay stock bore the earlier blocks can easily do 7-800 as long as you tune for zero detonation.

e85 sure helps if you are pushing up over 700

I wouldn't hesitate to refresh the LS engines. Throw some decent pistons and rods in there and call it a day The LS parts are pretty cheap

Summit has the ls pro series where you can get rods and pistons for 1200 or so which really is pretty good and they are rated up to 1200 which should do it.

 

If you remember it wasn't that long ago that was the way.
I had multiple engine builders tell me to stay with the 243 heads just massage them a little, and stuff good parts inside and as you said, zero problems.

 

Can I punch my ls6 out to a 408 and retain a good rignland for boost? I'm thinking of trying to stay in the 10-10.5:1 CR, same as stock

 

From what I been told and seen, keeping 346, run 10:1 is better for normal boost street stuff. Boost don't need big cubes, you have boost. Efficiancy is your friend, as well reliability. Not exactly sure about 408 and the LS6, typically you would find an LS2 for that and go 402, or find a LS3.
LS6, stock crank, good rods and pistons, good blower cam like ECS, AA jam, BT, good parts inside the stock but lightly massage 243 heads is all you need for good safe reliable, affordable power
YOU can be at 700-750 whp which for these cars being so light is actual great usable power. I have left 950whp cars with my 600whp 04Z like they were anchored because they can't put it down on the street.
My good friend runs simple LS6 stock bottom end, just Cam and worked heads with a ECS 2000 runs 685whp for 30,000 miles still with zero problems.
I run total stock LS6, just headers, meth, ECS2000 barely 6psi, just shy of 600whp, in a car that's 3,040 pounds, its fast. also 30,000 miles since installed zero issues.

 

dave is right, Ls6 block is not a good candidate for big displacement. You scan run a 4.0 crank for a bit more, but the 346 stroke is better for the pistons and you can make as much power as you need out of stock or even lower displacements

the ls6 has thinner liners in the blocks prior to 03 and can't be over bored much at all, and it's not really a good block because of the windows for bay to bay breathing to sleeve to get to bores up over 4.0 for larger displacements

if you want a big cube motor, the ls2, ls3 and iron block stuff is a much better choice

I'm going the opposite direction and running 5.3 blocks with the thick liners and just running more cfms through the blowers and turbos. The much stronger gen4 blocks are the ones you want

the big cubes just really aren't needed and make it harder to contain the higher cyl pressures. Go with the block strength and shorter strokes and make power higher in the rpm band to keep the big cyl pressure away from the torq peak to make the internals live a long and happy life by tuning for zero detonation. The shorter strokes keep the pistons in the bores and more stable. Less rod angle and friction. Big cubes are way more essential when you are NA.

Kenny Duttweiler built a destroked LSX engine with the smaller bore size and made big 3k plus power out of around 280 cubes. The the turbos do the work and build the engine strong enough to survive what they can dish out

thicker liners and keeping the heads down is the issue.