Originally Posted by mikeyg36
A DOHC V6 is smoother than a pushrod anything. Sit in a V8 Camaro at idle, and then go sit in a Mercedes V6 at idle. There is a complete difference. The Camaro is louder, and it shakes due to the cam. Of course, if you buy a V8 Camaro, you like these things. If you're buying a cadillac, you won't like these things. Caddy is trying to be more European, and it can't do that with a small block.
I don't fully agree. A V6 is inherently rougher than a V8 all other things the same, pushrod or not. In a V6 luxury car, they just put more into things like engine mounts to insulate the rest of the car from the engine. The engine isn't necessarily smoother, the vibration just doesn't get transmitted as much. And the somewhat shakier idle of a higher performance engine has more to do with the cam profile, not the position of it on the engine. And besides, the LT1's VVT will probably mitigate a lot of the "shake" (to the extent it exists) the LS3 has at idle.
I've experienced a lot of reasonably smooth pushrod engines, while at the same time, there have been some notably rough, unrefined DOHC V6 designs. Either can be made very smooth and refined or not so depending on factors having nothing to do with where their cams are placed.
If GM feels it needs both a V8 and DOHC to be competitive in all its various segments, why not build a DOHC V8 like Toyota, Nissan, Ford, Hyundai, Mercedes, and Audi all do. Wouldn't one engine be more cost effective than 2? Don't get me wrong, I love GM's pushrod V8s (as they do have certain advantages over DOHC), but I am still just as happy overall with my DOHC one, too.