Besides displacement what else (if any) is the difference between the LS2 and LS3. Why did Chevy abandon the LS2 - for 30 more HP?

I know LS2 uses LS6 (C5 Z06) 243 heads. Does LS3 use a better flowing head or the same head? Does the .2 liter (7 cubic inches) size difference cause the 30 extra HP? I guess why is an LS3 more desirable than an LS2?

 

First off I am not an expert, but I think I remember reading they moved away from the "cathedral" heads for better flow.

 

some link i found that may be helpful for you

http://www.vetteweb.com/features/vem...s3_engine.html

 

I have pasted the article for easy viewing and heads were the biggest difference and the LS3 really wakes up with mild mods, headers, CAI and exhaust with a tune

2008 Chevrolet Corvette - First Drive

This drawing shows the foam... read full captionThis drawing shows the foam insulation "sandwich" on the intake manifold, as well as the larger intake valves.As we mentioned in our main story, the new LS3 is rated at 430 horsepower and 424 lb-ft of torque with the standard exhaust system. This increases to 436 horses and 428 lb-ft with the optional exhaust.

To achieve those numbers, the engine features a larger-bore block (4.06 inches vs. the LS2's 4.00 inches); high-flow, LS7/L92-style heads; larger-diameter pistons; hotter camshaft timing; a revised valvetrain with offset intake rocker arms; a high-flow intake manifold; and the larger fuel injectors from the LS7.

In addition to its larger bores, which help create a 376ci displacement,the block casting also features revisions and machining in the bulkheads that enhance strength and improve bay-to-bay breathing. New pistons are designed to suit the LS3's high-rpm performance capability.

The new heads use straighter, larger-capacity intake ports to optimize flow to the combustion chamber. The exhaust ports are also designed for enhanced flow. Complementing the enlarged ports are upsized valves. The intake valves increase in diameter from 2.00 inches to 2.16 inches. They feature lightweight hollow stems, which contribute to the engine's 6,600-rpm capability. The exhaust valves are also bigger, measuring 1.60 inches versus the LS2's 1.55-inch units.


GM displayed this cutaway... read full captionGM displayed this cutaway LS3, which shows the inside of the engine's intake and exhaust manifolds, cylinder bores, and other points of interest.To accommodate these large valves and enable more-direct intake-port flow, the intake-side rocker arms are offset 6mm between the valve tip and pushrod. Actuating the valves is a new camshaft, with intake-side lobes providing more than a five percent increase in lift (now 0.551 inch). Exhaust-valve lift remains unchanged from the LS2.

Ensuring the cylinder heads receive all the air they can handle falls to a new, acoustically tuned intake manifold. The composite design is manufactured with a "lost core" process that minimizes runner-to-runner variation and reduces airflow losses. An acoustic-foam material is used to reduce radiated engine noise; it is sandwiched between the outer top of the manifold and an additional "skull cap" acoustic shell. Also, engine covers feature a noise-reducing insert to provide a more refined engine sound.

Chevy personnel provided Team VETTE with the following performance data:



* 0-60 4.1 (manual) / 4.3 (automatic)
* Quarter-Mile 12.4 at 117 (manual)
* Top Speed 190 mph
* Skidpad 92g (base) / 98g (Z51)
* Nrburgring Lap Time 7:56 (Z51)


The LS3 makes the six-speed, paddle-shifted C6 the fastest automatic-equipped Corvette ever. The LS3 manual, meanwhile, is faster than a C5 Z06. Now that's what we call progress.