Besides the increased capacity, what differences is there between the two engines ? How many of the parts are interchangeable ?

Thanks all.

Here is the 3.0
The DOHC G6AT and G4HA (also called the 3.0 D) both displace 3.0 L (2972 cc). They share the 2.5's 76 mm (3.0 in) stroke but use a larger 91.1 mm (3.59 in) bore. Output for the older G6AT is 182 hp (136 kW) at 6000 rpm and 178 ft·lbf (241 N m) at 4500 rpm, while the G4HA produces 180 hp (134 kW) at 6000 rpm and 188 ft·lbf (255 N m) at 4000 rpm.

The older SOHC 3.0 S produces just 158 hp (118 kW) at 5000 rpm and 177 ft·lbf (240 N m) at 3000 rpm.

Applications:
* 2001 Hyundai XG300

The 3.5
The G6AU and G4HC (both also called the 3.5 D ) are the large 3.5 L (3497 cc) versions of the Sigma engine. Bore and stroke are both larger at 93 mm (3.7 in) and 85.8 mm (3.38 in) respectively. Output is 200 hp (149 kW) at 5500 rpm and 214 ft·lbf (290 N m) at 4800 rpm for the older G6AU V6 and 217 hp (162 kW) at 5500 rpm and 232 ft·lbf (314 N m) at 3500 rpm for the new G4HC Sigma.

The 3.5 D has a cast iron engine block and aluminum DOHC cylinder heads. It uses MFI fuel injection, has 4 valves per cylinder, and features forged steel connecting rods. It is designed to run on "regular" unleaded gasoline rather than the premium fuel used in many other high-output V6 engines.

The US-market version produces 194 hp (145 kW) at 5500 rpm with 219 ft·lbf (297 N m) of torque at 3500 rpm. It was introduced with the Kia Sedona minivan in 2001 and was, at the time, the largest engine offered in a minivan and the second-most powerful. Since then, many other makes have passed it on both counts. It has been more of a Kia than Hyundai engine, with the Santa Fe and XG350 coming later.

This Engine is no longer used by Kia/Hyundai automotive group.

Hope this helps!!

This post has been edited by Getovait2005: Jun 22 2008, 12:53 PM

Thanks for that, but I've already read the wikipedia article. Didn't end up getting the 3.5L in the end, still only have the 3.0L.