Alfredo Ruiz

I know the no replacement for displacement. But not always true.... should I build an ls2 block 402 or ls3 416. And why?

A.R. Shale Targa

iTrader: (2)

The 402 is pretty much a square (4.005" X 4.00") combo and is a tried and true torque monster. Those who choose to start with the 416 (4.070" bore) usually do so in order to unshroud the larger 2.165" intake valves of a LS3 style rectangle port.

74u

iTrader: (9)

Make sure you find the piston you want to use (in stock and on the shelf) before you lock in the block.

I was faced with this exact scenario. I wanted to rebuild my LS2 402 and found I was going to need a new block. The cost was so close I chose the LS3 block for what seemed to be no brainer reasons (more cubes/less shroud).

I didn't do my homework well enough (check piston availability for myself) and my decision trapped me into a less ideal piston/combustion chamber size. I'm now limited to the heads on my car and will be very difficult to change combos.

Just my $0.02

Alfredo Ruiz

I will be using ls3 heads. It's going in a g8. Another thing I'm starting from scratch. I have no block no heads.. nothing lol..

Alfredo Ruiz

What compression ratio u running. And what did they not have available piston wise for your build... what heads u running?

Tuskyz28

Thing is with the bigger bore 416ci you'll always have more head options......
I'm my opinion you not go be able to tell a difference between a 402 to a 416. The reason I say that is because it's go literally cone down to head selection/cam size/ intake etc....
I have seen some 408 cars be faster than 427 cars. Why because the 408 has a better head/cam combo. So it's not really all about cubes. They help but they not everything.

Alfredo Ruiz

Oh yes also forgot to mention I will be using gm ls3 cnc heads

Tuskyz28

Then you'll want to go with the 416ci. The bigger bore helps the big valve heads do what they suppose to do.

Alfredo Ruiz

Thanks for your input

A.R. Shale Targa

iTrader: (2)

if you are set on the GM casting, consider the Advanced Induction exhaust only ported heads as the stock runner at 260 cc is already large and then a cnc job makes them 275-280 cc.
my friend has the Texas Speed (PRC) 255 cc ls3 heads on a 416 and loves that it has crazy torque at any rpm with a smallish 231/236 cam also from the guys at Texas Speed

KW Baraka

iTrader: (7)

Well......the 427ci that I'm about to drop into my 2014 SS is gonna come in at 12:1 SCR.

My cam is gonna come in at 242*/254* int/exh duration.

BTW.....the long block from a 5,000 mile LS3 would supply you with most all the part you'd need for your build (block/complete heads/intake/exhaust/oil pan/timing cover & chain/etc); you'd just need a cam and rotating assembly if you go stroker.

LMK If interested.

KW