CamaroZ28.Com Message Board - Ruthless Pursuit of Power: 2010 Edition In-Depth Look the Camaro SS's LS3

http://www.camarohomepage.com/ls3/index.htm

Chevrolet may be last to enter the "neo-pony-car" market segment with the 2010 Camaro, but, when you look at its 6.2-liter, 422-horsepower LS3, optional with six-speed manual in the SS models, as far as power and fuel economy go; the 5th Generation of one of America's iconic musclecars matches anything Challenger or Mustang bring to the table.

The new Camaro's Generation Four Small-Block V8 has great genes. It's the brother of the Vette's base V8 and a "little cousin" of the ZR's 638-hp, supercharged, LS9 and the Z06's 505-hp, LS7. Its ancestors are the LS1, in the '98-'02 Camaros, and the LS6, used in a few 2002s.

The General Motors Powertrain (GMPT) "Gen3" and "Gen4" V8s are some of the World's great engines. Performance-wise, they beat Ford's OHC V8s like a rented mule. They've been on Ward's 10 Best Engines List not just once, but three times since 1998.

Still not a believer? Ask Chrysler. In the late-'90s, during it's development of the modern "Hemi" V8, it benchmarked GM's Small-Block architecture, then reproduced some aspects of it in the 5.7-liter Hemi it introduced in 2002. Chrysler borrowing from that design for V8s in its trucks and performance cars says much about GM's engine technology. Some might be disbelieving of the Gen 3 V8 being inspiring to a competitor but, if you ever see the two short blocks apart, side-by-side on a bench; the influence will be noticeable. Imitation is the finest form of flattery.

Short Block Details

From the outside, the LS3 case looks maybe a little like the last Camaro's LS1 block. If you have sharp eyes, you can see the larger bore, but other major changes are inside. Image: GMPT Communications.

World-class engines start with stout blocks or "cylinder cases" as GM Powertrain engineers say. The LS3 case shares basics all aluminum Gen 3s and 4s have had since they debuted in 1997: deep-skirted, 319-T7 aluminum block with siamesed, cast-in-place, gray iron liners which are centrifugally-cast to increase density and allow thinner walls; long, 11-mm head bolts threading deep into its main bearing webs and six-bolt, sintered steel main bearing caps. All this makes a lightweight, rigid, block structure offering good durability and reduced friction.

The 2010 Camaro SS's 376-cubic inch, LS3 uses the same case as the Corvette ZR1's LS9, except for the "SC" engine's larger head bolt threads, piston oilers, forged steel main caps and its deck plate honing process. Other than that, everything done for the LS9 block carries into the new Camaro's LS3.

There are many improvements in the LS3 case, compared to the LS1/LS6 block in Camaros when production of the 4th Gen cars ended a little over 6 years ago. First off, its liners have 4.065-in bores, 0.167-in larger than LS1, and its main bearing webs are significantly stronger than those of the Gen 3 block through improvements in cylinder case design and manufacturing.

A bottom view of the LS3's case shows the mountings for the six-bolt, crossbolted, main caps. Image: Steve Constable/GMPT.

One of the windows, as viewed from the head deck. As the piston moves up and down in the cylinder, the volume below the cylinder fluctuates rapidly. The air blown in and out of the bay by that causes significant oil windage. Windows in the webs allow "bay-to-bay" breathing with much less windage in the oil pan. Image: Steve Constable/GMPT.

This "math art" shows the differences between the pre-'09 block windows and the change in windows for all Gen 4 blocks starting in 2009. The new windows are larger in area and asymmetric in profile. Image: GMPT Communications.

About half that additional strength comes from a redesign of the "windows" between each cylinder's "bay" in the crankcase. These windows enhance "bay-to-bay breathing" in the interest of oil control and reduced parasitic loss from crankcase windage. GMPT did a great deal of finite element analysis (FEA) and other types of computer modeling in search of a reliability/durability margin at the LS9s, projected 656-hp similar to what other Gen 4 engines had at their lower power outputs. This research indicated that the windows in all three center main webs could be strengthened by reshaping them in a manner that altered the stress concentration in each web. This reshaping, also, resulted in a slight increase in their areas. "Those windows are larger and have a non-symmetrical shape," Small-Block Assistant Chief Engineer, Ron Meegan, told the Camaro Homepage. "When we made them larger, we were able to move the edge of the opening to a thicker portion of the bulkhead and that is where the strength improvement comes from. We were able to get to this sweet spot using finite element analysis. We incrementally increased the size of the window until we reached the maximum safety factor. If we go larger than this, the safety factor begins to decrease because the size of the hole overrides improvement from the increasing thickness of the bulkhead."

The net result of the window alterations on Gen 4 blocks, which were done in two stages, the first for the model year (MY) 2006 and the second for 2009, was an 18% increase in strength of the webs.

For Camaro engine geeks, this is the Mother Ship, where most of the engine engineering is done--GM Powertrain's World Headquarters in Pontiac, Michigan. Image: CHpg Staff.

John Rydzewski is a Camaro engine ace, both figuratively and, as was the LS3's Assistant Chief Engineer (ACE) for most of the engine's development, literally. Rydzewski worked on Camaro V8s as far back as 1993 and he was ACE from 2005 to mid-'08. Image: CHpg Staff.

A while back, we visited GMPT's World Headquarters in Pontiac, Michigan to interview John Rydzewski, who was Assistant Chief Engineer for Small-Block Passenger Car Engines until July of '08, but has since been transferred to head a future engine program. Rydzewski lead the team of engineers who developed Camaro V8s and the one subject we breached was the increased block strength. "When the block is honed, the bottom of the honing tool needs clearance so it doesn't contact the block below the bore." Rydzewski explained. "Before the honing operation, the block is machined in that area to provide (hone over-travel) clearance. The resulting surface geometry has a big impact on the block structure. The hone over-travel clearance used to be machined with a 3-mm radius. With LS7, to get more strength in that area, we changed to a more gentle, 8-mm radius. That was a big durability enabler at the LS7's power level. When we got into the LS3 finite element analysis (FEA), we found our safety factor needed some improvement, so we applied what we learned about LS7's hone over-travel cut-out. We were able to increase the radius to 10-mm which was worth about an 20% improvement (compared with blocks having the 3-mm radius) in the strength of the block structure in that area."

In the interest of simplicity, starting in MY09, all Gen 4 blocks are now machined with the window changes and 10-mm. hone-over-travel radius. At the Camaro LS3's power levels, the cumulative result of these changes increase main web strength by about 36% compared to that of the LS1 used in the '98-'02, 4th Gen Camaros.

These changes to the main bearing webs in an LS3 case (right) might not look like much, but they make a huge difference in the strength of the lower end of the block. Image: Steve Constable/GMPT.

In Camaro LS1 and LS6 blocks, the bores were siamesed except for the top 20 millimeters or so which had a small slot through which coolant flowed. That slot was there because, at the top of the bore, where the most heat is generated, extra cooling was required. It's important for bore wall and piston temperatures to be as consistent and as cool as possible. If the bore has hot spots, distortion will result and that's not good for compression, oil control or friction, so, with Gen 3, to reduce distortion of upper ends of the liners between cylinders; coolant flowed between the bores. The downside of that was manufacturing complexity and some weakness in the block in the vicinity of those slots.

During the Gen 4 development, the water jacket design was improved to get good heat rejection without water between the bores. Computational Fluid Dynamics (CFD), one of GM Powertrain's computer analysis tools, allowed the Small-Block Team to model coolant flow in the water jackets and project the quality of bore cooling if the design was altered. CFD can examine water flow profiles, movement of particles in the water and where eddies or divergent flows occur. Engineers can see coolant flow on a computer display and that enables them to more easily predict the effect of water jacket improvements. Once a particular change demonstrates effectiveness in the virtual world, it can be quickly applied to actual hardware.