mfernandez72490

I have one question regarding the GEN 3 Ls block and the GEN 4 ls block.

I wanted to know what are the main differences as far architecture of the block?

What differences AND changes were made to make the block better?

And are the heads for both blocks interchangeable between each other?

Always2Slow

iTrader: (8)

All the cylinder heads are interchangeable. The ls2 block shares alot of things in common with the ls6 but was tweaked to make it even better. Some things are bay to bay breathing in the crank case and improved oiling passages. I would say 90 percent of parts are interchangeable between a gen 3 and a gen 4, but don't quote the percentage. Another difference you should note is gen 4s has a 58x reflector wheel on the crankshaft where gen 3 uses a 24x and are not compatible with each other.

djsanchez2

iTrader: (14)

^^^ +1
Also:

the location of the knock sensors moved from the valley to the outside of the block.
the head bolt lengths changed
drive-by-wire throttle body
The MAP sensor moved
More ribs for strength

The_Rizzle

iTrader: (4)

cam sensor moved as well? From rear of cam/block to timing chain gear/front cover.

Timing tensioner bolts spaced differently?

Steve - Race Eng

iTrader: (1)

The water jacket is raised ~.750" on the Gen IV blocks vs. the Gen III. Also the Gen IV blocks are true siamesed bore blocks. The Gen III blocks have a coolant transfer passage between the bores from just below the deck surface to about two inches down. The lack of coolant crossover passage between the bores makes the Gen IV blocks capable of being dry sleeved for increased displacement where the Gen III blocks need wet liners for large bore with reliability.

Steve

Tommyv8

iTrader: (8)

All of the heads are interchangeable? I was under the impression that you need at least a 4.00" bore for some of the Gen IV heads, like the L92 and LS7.

Always2Slow

iTrader: (8)

They will bolt up but the valves will hit on l92 heads or ls7 heads. So if you sleeved the block they will work.

Camaros-n-Chevelles

iTrader: (3)

Is the LSX considered a Gen 3 or Gen 4 block?

Know It All

Its considered a race block.

But last I checked, it didn't have a provision for a rear can sensor, so it is probably resembles the Gen IV blocks more than the Gen III.

Camaros-n-Chevelles

iTrader: (3)

Perfect. That is what needed to know. I already purchased the wiring harness for the LY6. Now if I decide to upgrade to the LSX, I just wanted to make sure that the wiring will remain the same.
Thank You.

joecar

Gen IV LS3 block also has provision for AFM/DoD and VVT.

voaitnient

I already purchased the wiring harness for the LY6.

blk00ss

iTrader: (66)

Yes the LSX block requires a ls2 conversion unless being used Ina ls2 vehicle.

Sethlorton

So if I have a set of 317 heads off of a gen 3 6.0 they will bolt right onto a gen 4 6.0?

LS1Formulation

iTrader: (13)

Yes they will.