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Ruthless Pursuit of Power: 2010 Edition
Our In-Depth Look the Camaro SS's LS3
by Hib Halverson, Content Director

 

Image: GMPT Communications

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.

The LS3 block from the top side. The pairs of bosses adjacent to #1, 4, 6 and 7 cylinders are for the AFM hardware. Image: Steve Constable/GMPT.

The resulting changes to block cooling enabled the slots to be eliminated for Gen 4. The resulting heat rejection did the same or better job with cooling and controlling bore distortion, but also resulted in a case that is reliable and durable at any of the Gen 4 power levels, up to the LS9's 638-hp.

The LS3 connecting rod is based on the original LS1 forging. GMPT has used powdered metal rods since the Gen 2 Small-Block years. Steel powder is poured into a mold which is then heated and subjected to great pressure. This "sinters" the steel into the rod form. From there the rod goes through a conventional forging process and shotpeening. Image: CHpg Staff.

Another major change was the addition of structure to the block valley to accommodate the hardware for Active Fuel Management (AFM), the Gen 4 Small-Block's cylinder deactivation system. It will not be used in the Camaro LS3, but will be in the L99, the car's, 396-hp automatic trans V8. The knock sensors, previously atop the valley cover on an LS1, moved to the sides of the block to make room for AFM pieces. In addition, the extensive FEA the Gen 4 cylinder case underwent resulted numerous, other, small structural changes to the casting which improved strength and decreased mass.

LS3's nodular iron, rolled-fillet-journal crankshaft is similar to those used in LS1 and LS6 engines except for counter weights altered to rebalance the engine for a slightly heavier piston. The connecting rod is basically the same–6.1" long, PF1159M powdered steel, sintered, hot-forged, and shotpeened–as in the LS1, except it now has a slightly larger small-end which enables it to be bushed for a floating pin, a change made to reduce cold piston knock and as a reliability/durability enhancement at the 422-hp level. These rods are "net shape" so post-production machine work for balancing is not required. As before, they're "cracked rods" which means that, to simplify manufacturing and enhance fit between rod and cap, the big end is fractured in half rather than cut and machined.

Rods with cracked or "fracture-split" big ends are common on modern engines. The fracturing creates a unique interface that "locks" together only one way and does so very precisely. The more accurate interface ensures a uniform big end diameter and shape. Image: CHpg Staff.

Starting with the LS2, Gen 4 V8s use a full-floating wrist pin, so the rods are silicon-bronze bushed and that bushing has an oil feed groove milled into it. Image: CHpg Staff..

Also new are the rod bolts. They're made of stronger material which meets the same grade 12.9 specification as do LS7 and LS9 bolts. The design of the rod bolt was changed, too. "An alignment feature was added to the shank of the fastener," John Rydzewski told the Camaro Homepage. "Unique threads are rolled into a short length of the shank. Compared to the standard threads, they have a larger outer diameter which provides alignment to the rod hole and they have a smaller minor diameter which provides an additional benefit of isolating much of the plastic deformation from yield to this rolled section of the fastener.

The LS3 rod bolt uses two different thread sizes and diameters to control bolt stretch. Image: CHpg Staff.

"A connecting rod bolt will have deformation along the length of the fastener which results in concentrated stress at the first engaged thread. Since unengaged bolt threads are able to freely stretch, while engaged threads are constrained by the threads in the rod, the first engaged threads are more highly stressed.

"The new Small Block bolt is similar to a 'necked-down' fastener, where the bolt stretch/deformation will be focused in a portion of the length of the bolt not near the first thread of engagement. Therefore, the concentrated stresses at the first thread of engagement will be less and the overall joint safety factor improves."

 The grade 12.9 material coupled with the improved  bolt design, allows clamp load at the rod cap interface to go from 47 kilonewtons to 50kN.

More cutting-edge technology is in the LS3 piston and ring package. The piston is a flattop design, cast with a hypereutectic, aluminum/silicon alloy containing traces of copper and nickel. Its ring grooves are machined with a slight upward tilt which was increased by 0.25° over what was used in the LS1. The top ring's tilt disappears as the ring land flexes under the pressure of combustion such that sealing and oil control are optimized. The other two grooves' tilt enhances the ability of the second and the oil rings to scrape oil off the cylinder walls. To further improve oil control, the LS3 piston has four holes drilled in its skirt, just below the oil ring groove, downwards into its interior. These holes, two adjacent to the major thrust surface and two adjacent to the minor thrust surface, improve oil drainage from below the oil ring.

In the early LS1 years, because of the Gen 3/4 engine family's short-skirted pistons, cold piston knock was a customer pleasability issue. Since the '02 LS6, Gen 3/4 pistons have had a polymer coating on their major and minor thrust surfaces–the gray area on this LS3 piston skirt. At the end of the break-in period, a lot of the polymer and a slight amount of piston material is worn away, leaving a very consistent skirt surface, a nominal (and tight) piston-to-bore clearance and hopefully, no cold piston knock. Image: Steve Constable/GMPT Communications.

Here's a "bare" LS3 piston. The hard-anodizing adjacent to the top ring groove is a durability feature. While the oil drainback notches have been in Gen 3/4 pistons for a long time, new are the oil drainback holes, two each, above the major and minor thrust faces, drilled into the piston interior. Image: CHpg Staff.

The underside of the LS3 piston. As the piston moves down in the bore, oil is scraped off the walls by the oil ring then is "flushed" down the oil holes and into the interior of the piston. Image: CHpg Staff.

To enhance durability, surfaces either side of the top ring groove are hard-anodized. The piston skirts are coated with the antifriction polymer introduced on LS6 for MY02. Interestingly, the pistons are installed with -2 micron (-.00008-in or negative eight hundred-thousandths of an inch) piston-to-bore "clearance"–a slight interference fit. During break-in, some of the coating wears away, leaving a nominal piston-to-bore clearance. LS3 pistons use new wrist pins having tapered inside diameters, an idea straight from the Corvette C5R race program and which reduces pin weight with no loss in strength.

The LS3 uses a wrist pin with a tapered inside diameter. The benefit is reduced weight. because the farther the pin penetrates into the piston pin bore, the less strength is needed in the pin wall, the tapering does not affect reliability/durability. Image: CHpg Staff.

The LS3 piston and ring package is typical of what GMPT has used since 2002 in high-performance SBV8 applications, but with more groove "tilt" and higher oil ring tension. Image: CHpg Staff.

Oil control at high rpm has been a challenge with Gen 3/4 engines. Since 1997, to that end, GM has tried several combinations of positive crankcase ventilation systems, ring tension and oil pans. It has also changed the ring groove design as detailed above.

656.16) The top ring is the most critical part of compression sealing and, in an LS3, it's a pretty trick part with one of those tricks being a slight twist to the ring. Drawing: CHpg Staff.

With the rings in simulated position on a piston, you can easily see the hook-like, Napier-faced, second ring. "Napier rings" are much better at scrapping oil off the cylinder walls as the piston moves down and that's the reason GM upgraded to them for 2002. Image: CHpg Staff.

For the LS3, the ring package has, once again, been changed. The top ring is still moly-faced steel and "coin twisted," which means its shape in side view is slightly conical to improve the ring's sealing when under combustion pressure. The second ring remains cast iron with the "Napier" face introduced in MY02 and they both are 1.5-mm. wide with the same tension as before. The oil ring is still three-piece, two rails and an expander, however, to improve oil control in the LS3, its tension was increased.

When engineers talk about "oil control", they mean control, not only in the oil pan, to keep the oiling system from sucking air, and control by piston ring and ring groove design; they mean oil control through the crankcase ventilation system, too. There are two sides to any PCV system, the "fresh side", where air goes into the crankcase and the "foul side," where dirty air comes out. On Gen 4 engines, both sides have oil separators. The foul side separator is the most important because that's where there is oil in the crankcase ventilation flow virtually all the time. Blow-by goes in the crankcase, through the foul-side separator then is consumed in the engine.

LS3 has a new design for that separator. It shares the same location as the LS1's, but internally, it's quite different. Once again, computational fluid dynamics played a part in development, but this time, with the addition of some proprietary GM software code called “Rain Drop Analysis”. CFD with RDA is able model the flow of air in which oil is suspended as it goes through separator. The data gained from that helped engineers develop baffles which would better separate the oil from the air. This unique oil/air separator design is so effective that it was patented. At the time rain drop analysis was paired with CFD for the initial Gen 4 development in 2002, it was a revolutionary computer modeling tool. Even today, few companies utilize it because of the immense computer power necessary to run it.

Ideally, you want to separate all the oil and return it to the crankcase and only have the engine ingest air and blow-by gases. In practice, you burn some oil, but it needs to be as little as possible. It there's too much oil in the PCV flow, oil consumption will rise. With the LS1, when there was a lot of air moving through the PVC system at high speed but the engine was only lightly loaded; the system wasn't efficient at separating the oil from the air, so those engines suffered higher oil consumption than engineers and some 4 Gen Camaro owners would have liked.

Not only does the LS3 have significant improvement in its foul-side, oil/air separator, it also has less blow-by air flow under those conditions. Less blow-by under high-rpm/light-load conditions and a more effective separator means less oil consumption.

At high-rpm and wide-open-throttle, blow-by flow can reach the capacity of the foul side. That capacity cannot be so large that it would never be exceeded because it's undesirable to constantly consume large quantities of crankcase air through the intake side of the engine. You want to consume only enough that you're constantly purging the crankcase vapors adequately. At light load, there is an assist from manifold vacuum which insures constant crankcase purging. That reduces sludge formation and burns hydrocarbon pollution.

The Camaro LS3 oil pan with its engine oil cooler attached. Image: GM Powertrain.

At WOT, there is no vacuum to help pull the air from the crankcase and, also, there is more blow-by; so you exceed the flow capacity of the foul side, which is sized for most normal light load operation.

Often there is enough blow-by at WOT that the clean-side air flow reverses. If that happens, it might force oil into the intake. That's why Gen 4 has oil/air separation on both the clean and the foul sides.

The oil pan used on the Camaro LS3 is quite a bit different than the one used on LS1s in the 4 Gen cars and it's different from the one used by the LS3 when it was introduced on the Corvette for 2008. The Camaro pan is a bit bigger inside holding a additional two quarts of oil compared to the Vette LS3. Otherwise, the pan is similar in concept to other Gen 3/4 oil pans in that, besides holding all the oil, it acts as a sound insulator and add some rigidity to the bottom of the block. In addition, the Camaro LS3 has an engine oil cooler because, according to ACE Ron Meegan, "...of the (vehicle) weight and the (reduced) air flow around the engine in this package, some of the more aggressive driving modes required us to use a cooler to meet our oil temperature requirements." The Camaro oil cooler is the same type of oil-to-coolant heat exchanger used by the supercharged LSA in the Cadillac CTS-V and it is mounted in a similar location, on the left side of the oil pan.