The LS6 engine does have a higer compression ratio than the stock LS1 engine but what i want to know is where is that extra compression coming from the pistons in the bottom end or does the LS6 heads have a smaller combustion chamber in the heads that raise the compression. Also what is different in the LS6 bottom end and the 2002 LS1 bottom end i know they have the same blocks but are the crank and rods the same?

thanks

 

Hi
LS-6 cylinder heads have smaller combustion chambers to get higher compression(5cc -7cc smaller)Crank and Rods are the same as LS-1,Cast.Pistons in both engines are cast.
Nice upgrade for these engines are Lunati forged crank and rods and a set of Ross forged pistons.1/2 inch stroke on the crank is nice too!
Ray T
2002 EBZ06 :cheers:

 

FYI: LS1 is 10.1:1 compression ratio

 

LS6 = 10.5:1 CR 60 cc chamber
LS1 = 10.1:1 CR 68 cc chambers

New Pistons

LS6 pistons are cast from high-strength M142 aluminum alloy and reshaped with a slightly different profile than those in the LS1. In side view, the LS6 pistons have a slight barrel shape, almost imperceptible to the naked eye. The new alloy increases engine durability at racetrack operating levels, while the
shape reduces internal mechanical noise.

Increased Compression

The LS6's aluminum cylinder heads are cast with smaller pent-roof combustion
chambers than the LS1. Compression ratio increases from 10.1:1 to 10.5:1,
improving thermal efficiency and increasing horsepower. Intake and exhaust
ports in the LS6 head are refined and more-precisely cast, contributing to the
engine's overall increase in volumetric efficiency.

Also to note: The 2001+ Aluminum 6 liter truck head is identical in every way to the LS6 casting, except with about 4 to 6cc larger combustion chambers to acomodate the 4 inch bore on the Truck motor.

An Ideal and prevalent head for forced induction.

 

Thanks alot for the feed back. I have been waiting for a few experienced gearheads to reply. Yeah i figured that the combustion chamber of the heads is mainly what causes the increase in compression since the increase is so small, but i also figured that GM also used different pistons as well. From what i have read though the pistons used in both motors are hypereutectic pistons and not cast can someone comfirm this. Also i didn't know that the truck heads are the same as the LS6 heads but with larger combustion chambers. That is awesome for forced induction applications. Oh yeah one last thing do the headers/manifolds for the LS1 bolt right up to the LS6 heads or are the exhaust ports on the LS6 heads raised for better flow so they need their own headers/manifold in order for them to bolt up to the remainder of the exhaust correctly. I will be in charge of the build up of my friends new 2002 vette and his goal is to go low 12's, but my plan will be more like low 11's (or possible high 10's !!). I'll make him grow the ***** he needs for this car since he just babys it all over town or if not then it will just be alot of fun for me to beat on it at the track and on the ride home for a night out where i end up being the DD.
thanks alot

 

Im not sure when the switchoever exactly occured, but this is from GM unit repair guide 2002:

Piston and Connecting Rod Assemblies

The pistons are cast aluminum. The pistons use two compression rings and one oil control ring assembly. The piston is a low friction, lightweight design with a flat top and barrel shaped skirt. The piston pins are chromium steel. They have a floating fit in the piston and are retained by a press fit in the connecting rod. The connecting rods are powdered metal. The connecting rods are fractured at the connecting rod journal and then machined for the proper clearance. Interim 2001 and all 2002 applications use a second design piston with graphite coated skirt.

 

Someone on the Z06Vette forum said they changed to cast in October..but no one has really been able to confirm that. Would be nice to know for those wanting to run a lot of N2O.