skopers3

iTrader: (3)

I upgraded to an LS6 over my LS1 this summer and will admit I can tell a small gain while driving, but I've always wondered this and am bored at work so figured I'd take a minute and finally ask, lol. Everyone says the LS6 is the best factory manifold you can get and is loads better than an LS1, but what's the physical difference? Sitting side by side they look identical except for an EGR hole, so how are they made differently that the LS6 is so much better?

madmike9396

iTrader: (29)

maybe bigger ports not sure

JRENIGAR

iTrader: (37)

I think the plenum and runner volume is a little bigger.

lemons12

iTrader: (71)

They are only marginally better. The ls6 starts dying out around 5800ish rpms or so. After that is where the fast intakes shine. Not sure where the ls1 intake starts dying off... it is a chocking point everywhere really. The ls6 on a stock internal or small cam only car can take you a long way.

thunderstruck507

iTrader: (18)

Flip them over and look again....see how the ls6 is flat? That's more volume. Also different runner design I believe.

A fast is even more volume, both taller and hugs closer to the valley cover, hence why it requires shorter head bolts for the valley cover when it's installed.