To answer the OP's question, both motors have different valvetrains and the LS3's is more aggressive than the L99's. The LS3 gets better fuel economy not due to the motor, but due to the increased efficiency in the transmission and the broader overdrive gears.
Quote:
Originally Posted by flyer08
If ls3 was so much better why are there so few on the fast list compared to l99?
|
You realize that there are 2 automatics for every 1 manual SS produced, right? There are more L99's in the "fast list" because there are far, far, far more L99's on the road than LS3's. America has this nasty habit of breeding folks that don't know how to drive manual transmissions, so that's why automatics are the new "standard." We have very unskilled drivers.
An LS3 makes 26 more horsepower and dynos with 5% greater efficiency. If you can drive a manual well, it will smoke an equal automatic every time. It is, simply put, impossible to be as consistent with an M6 as with an A6 since the automatic just requires one foot and no hands to drive, so it takes a bit of work to run a good ET with a manual in a perfectly straight line. By that same logic, you probably won't find a single L99 anywhere on a "fast list" on a track with a turn. Modded, both motors will have similar potential, but it'll cost a whole lot more to mod an L99. Typically, a cam swap on an L99 is an extra $1,000 over an LS3, and there are less camshaft options. Running from a roll makes it a bit easier to showcase the LS3+M6 advantage since it's a lot tougher to launch with a clutch. From a stop, the manual driver will probably have to play catch-up most of the time due to the increased difficulty launching.