Corvette LS Engines - Tech

Over the last dozen years, this LS engine series has gotten rather lengthy and even a little confusing. As we suspected on that morning in New Jersey, this engine was not designed just for the Corvette. Rather, it was going to find its way into a huge variety of engine compartments.

The Generation III, or LS, small-blocks replaced the LT family in 1997. They shared the same basic displacement and bore spacing (4.4 inches) as the earlier engines, but almost everything else changed.

If anything, the LS engine looked a whole lot like the Cadillac Northstar. A few GM engineers privately explained to me that the Northstar had really been a test for the new LS1. There was no way GM could justify a stand-alone engine for the Cadillac, but if it was a stalking horse for the LS1, then it was just fine. The Northstar sold in such small quantities that a screw-up wouldn't be the end of the world.

The new LS1 had a 3.9-inch bore and a 3.62-inch stroke. The idea was that this particular combination would provide significant low-end torque. Remember, it was being compared to the old LT1 engine. Performance had to be at least as good as the LT1.

This new engine also introduced coil-on-plug ignition to the small-block V-8. Finally, the Corvette could get rid of the Opti-Spark system. The cylinder firing order was changed to 1-8-7-2-6-5-4-3, so that the LS series now corresponded to the firing order of other modern V-8 engines.

The traditional five-bolt pentagonal cylinder head bolt pattern was replaced with a square four-bolt design. As the performance of this engine increased this would be a problem, but as long as you kept the power down to a reasonable level, everything was fine. Corvette Racing now runs a five-bolt cylinder head. Need to know anything else here?

The LS1 block is very different from pre-'97 small-block engine designs. Most of the internal parts, like the crank mains, front and rear covers, and oil pan, are designed to "find their own home," which simplified the machining process and eliminated the need for dowels in many locations. Good examples of this are the crankshaft main caps. These main caps swedge between the lower skirt walls of the cylinder block. GM engineers call this snap-fit cross-bolting. Cross-bolting refers to how each one is held in place with four vertical and two horizontal bolts.

The drumbeat for more Corvette power began almost as soon as the C5 Corvette was on the showroom floor. I can remember Dave Hill, the Corvette chief engineer, being besieged with questions about when "real" Corvette power would make an appearance. Being the good GM soldier that he was, Dave never hinted that the LS6 was just around the corner. But in 2001, we got LS6 power. This first step, which lasted only one year, delivered 346 horsepower and 385 lb-ft of torque with the six-speed transmission, and 360 lb-ft of torque with automatic transmissions.

When the '02 Z06 was introduced it got even better. Horsepower went to 405 and torque was increased to 400 lb-ft. Now people were happy-at least for about 10 minutes. Then the appeals for more power began anew.

Generation IV
In 2005, the Generation IV superseded the Generation III engine family. This marked the introduction of the LS2 engine into the Corvette. It was time to step up the displacement. This new generation of engines included provisions for displacement up to 7.0 liters (the magic 427 cubic inch number that Corvette owners all love and cherish) and power output to 638 hp. It was time to get serious.

A three-valve-per-cylinder head was originally slated for the LS7. That would have been a first for a GM pushrod engine. In the end, though, the idea was shelved because of design complexities. Besides, the basic two-valve configuration proved to be enough to meet the LS7's goals.

It's interesting that the LS3 came after the LS7. While the LS7 was designed for the Z06, the LS3 was built as a base motor to replace the LS2. A lot of new things were done with this motor. The most obvious was the increase in displacement, but the LS3's new cylinder heads may have been even more important. These new heads were based on the large port design used on the LS7 motors and featured larger and straighter ports, not to mention larger valves. All of this was coupled to a new intake manifold. Basically, the LS3 was a brand new engine, with only its basic architecture similar to the LS1 of 1997.

The latest chapter in the LS saga is the mighty LS9. This may be the ultimate LS engine. I seriously doubt if anyone considered a supercharged LS engine back in the early '90s. If they did, they were very quiet about it.

The LS9's 638 hp is surely impressive, but the 604 lb-ft of torque is even more astonishing. This engine took a long time to develop and may be the high point in the development of a gasoline powered Corvette. It's been a long journey from that press conference in New Jersey.

Today there is a Generation V someplace in the GM system. The gossip says that it's an overhead-cam engine with four valves per cylinder. It will feature variable valve timing and cylinder deactivation. This will obviously be a truck engine, but there could easily be a Corvette version. After all, the Corvette has done rather nicely with all of these high performance truck engines over the years.

The C5-R Cylinder Block
You probably haven't seen this engine. Actually, you may never see this engine in person. It was developed for the factory-backed Corvette Racing program. The C5-R cylinder block has been manufactured in very small quantities since 2000. Part of the reason for the low production numbers is that you have to pay more than $8,000 for just the bare block.

These engine blocks are manufactured with a unique 356M aluminum alloy for greater strength. They also undergo a variety of specialized machining and inspection processes, including a process known as "hipping." Hipping is a multistep heat-treating process that pressurizes, heats, and then cools the block to ensure strength and eliminate porosity.

A Siamese-bore design with 4.117-inch finished bores enables 7.0L (427ci) displacements. The C5-R uses billet steel main caps with premium 4340 fasteners. Racing-quality head studs are also included. All LS series heads will work with the C5-R block.

One reason (or at least a rumored reason) for the high cost of this block is that around 20 percent of them are rejected because of quality issues. It's not that the blocks are that bad. It's just that the standards are that high.

LS2 • '05-'07 Corvette
6.0L/364 ci
400 hp @ 6,000 rpm
400 lb-ft @ 4,400 rpm

LS3 • '08-'10 Corvette
6.2L/376 ci
424 hp @ 5,900 rpm (standard exhaust)
436 hp @ 5,900 rpm (two-mode exhaust)
418 lb-ft @ 4,600 rpm (standard exhaust)
428 lb-ft @ 4,600 rpm (two-mode exhaust)

LS6 • '01-'04 Corvette Z06
5.7L/346 ci
385 hp @ 6,600 rpm ('01)
405 hp @ 6,000 rpm ('02-'04)
360 lb-ft @ 4,400 rpm ('01 automatic)
375 lb-ft @ 4,400 rpm ('01 manual)
400 lb-ft @ 4,800 ('02-'04)

LS7 • '06-'10 Z06
7.0L/427 ci
505 hp @ 6,200 rpm
475 lb-ft @ 4,800 rpm

LS9 • '09-'10 ZR1
6.2L/376 ci supercharged
638 hp @ 6,500 rpm
604 lb-ft @ 3,800 rpm

ASA called the whole deal Project 2000. These engines developed 430 hp at 6,200 rpm, with torque reaching 430 lb-ft at 4,800 rpm. The redline was at 6,500, which was the same as the fuel shut-off point. When you compare these numbers to the stock LS1 it's a wonder this engine hasn't been more popular. It shouldn't be that hard to create one of these engines using parts from your Chevrolet parts department or from Lingenfelter.

The ASA initially ordered 300 engines for the 2000 season. I haven't been able to confirm that number, but it sounds reasonable. These engines were assembled at the Romulus, Michigan, plant and then shipped to Lingenfelter, where they were modified, dyno tested, and then sealed. ASA kept control of the PCM boxes and passed out sealed boxes before each race. These were special units developed by GM and had different values from the production units.

These engines used a more aggressive camshaft, higher quality valve springs, and a dry-sump oiling system. In 2000, these engines were sold to the ASA teams for $12,000. I ran across one of these engines last year and the owner was asking $11,000. Not bad considering that it had been raced for a decade.

LS by Kimble
Over the years, General Motors has commissioned cutaway artist David Kimble to render several of its engines for various press kits. Here are a few from the LS era.