Why is the LS Engine so good..

Discussion in 'Engine: Selection and Modification' started by bytor, Oct 9, 2015.

  1. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

    http://www.hotrod.com/articles/ls-turns-20-retires/
    https://books.google.com/books?id=8...hDoAQhhMAk#v=onepage&q=afr dyno tests&f=false
    The LS Turns 20 … and Retires
    Written by Jeff Smith on September 25, 2017
    GM Archives - Photography;
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    It’s enough to give the rest of the V-8 world an inferiority complex. Big, V-8 engines are very much an American thing while the rest of the world seems to prefer buzzy little four cylinders or perhaps quiescent electric motors. But here in the land of the free and home of More Torque, our preferences lie with big, powerful two-valve pushrod engines.

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    Perhaps it’s appropriate that the movie The Lost World, Jurassic Park opened in 1997, the same year as the LS1. Appropriate because this latest iteration of the small-block Chevy really made the Gen I small-block seem antediluvian. In a quick two decades, even that original LS1 now seems frail compared to today’s steroidal Gen V technology.


    We thought it might be fun to look back at how far this all-aluminum small-block has progressed, make some comparisons, and track its progression from the humble LS1 to the assertive Gen V LT1 and big-brother LT4.







    Legacy is an appropriate descriptor that’s often applied to the Gen III family of engines that grew out of the Gen I small-block of 1955. The LS1 retained several important design aspects, including the small-block’s 4.400-inch bore spacing as well as the same bellhousing bolt pattern. This nod to the past was no accident. These simple steps allowed car builders to easily adapt the new LS to older cars, creating a whole new segment of the performance industry.

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    While the Gen III is architecturally more similar than different compared to its Eisenhower-era predecessor with pushrods, two valves per cylinder, and a wedge combustion chamber, that’s pretty much where the similarities end. Besides the deep-skirted block that adds strength, the most significant changes were all in the cylinder heads. Port flow increased dramatically, accompanied by a radical shift from a 23-degree valve angle to a much flatter and flow-enhancing 15-degree angle accompanied by attendant changes in the ports that complemented the valve angle. Plus, a far flatter and more efficient combustion chamber allowed a welcomed increase in compression. The changes not only added power but were accompanied by improved fuel economy and lower exhaust emissions. This was the engineering equivalent of a trifecta.

    Taking a somewhat broader view, improving power and efficiency can only be achieved with control. If we look at the Gen III, it is a study in controlling events. The engine control Unit (ECU) knows not only where the crank is at all times but the camshaft as well and can manipulate performance and mileage with injector pulse width, electronic throttle control (ETC), and timing.

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    The ECU knows when the engine detonates and can adjust for that on the fly, compensating for elevated engine inlet air temperature, all while making tuning adjustments in millisecond increments. Even the smallest of the Gen III engines, the 4.8L and 5.3L truck engines, enjoyed major power improvements over the Gen I and II designs.

    The first big performance enhancement came with the LS6 bumping power by 55 hp to 405. It was clear a horsepower race was enjoined with the appearance of the 427ci, 7.0L LS7 touting 505 hp and 470 lb-ft of torque. Everybody wanted an LS7. It reminded the older guys of the rock ’n’ roll ’60s, right down to the RPO numbers. But what was this? A factory V-8 with a dry-sump oiling system? Only race cars have dry sumps. The sprint was now a full-on stampede. What could they do to top an LS7?

    The LS2 actually predated the LS7 and quickly experienced a few minor improvements that were sufficient to call it a Gen IV engine. This engine enjoyed a displacement bump to 6.0 liters with a 4.00-inch bore and base power of 400 hp, but that remained only for a short time until the LS3 debuted. Here was where the promise of big power began its climb.

    Engine guys could see the telltale signs with the single Internet digital image of those rectangle-shaped intake ports. Those ports where huge, everyone said. And the power numbers jumped again along with displacement now up to 6.2 liters (375 inches). Could it get any better? Absolutely!

    The horsepower escalator was hooked directly to GM’s dyno cell and those guys in the white coats were pushing all the right power buttons. You can only get so much from using atmospheric pressure, so the next best thing was to use a pump to push the air into the intake ports. The LS9 was essentially the answer to the age-old quest. The C6 Corvette raised the stakes with 638 hp and 604 lb-ft of torque using a Roots-style Eaton 2300cc supercharger on top of an already outstanding 6.2L engine. This made monster power and carried a warranty!

    This was followed by a milder LSA supercharged version for the ZL1 Camaro and Cadillac CTS-V, this time with a smaller 1.9L Eaton blower making 556 hp and 551 lb-ft of torque. Both the LS9 and LSA are now available as crate engines in Chevrolet Performance’s expansive 400-page horsepower catalog with the LSA the much more affordable of the two. Keep in mind as well that these are SAE horsepower and torque ratings that are much more conservative than the typical hot rod correction factor. The difference is the factory rating system is about 5 percent lower than the hot rod factor, meaning that a 556 hp rating for the LSA is roughly equal to 580 hp using the hot rod correction factor. This is true for normally aspirated engines as well.

    While power is always a good thing, control has improved at the same time. Fuel mileage has often thought to be the antithesis of performance, but creative engineering means coming up with ways to accomplish both. First it was variable valve timing (VVT), which exerts control over cam timing by allowing the ECU to advance or retard the cam as much as 62 degrees in Gen IV engines. Add to that what GM calls Active Fuel Management (AFM), which really is the art of pulling four cylinders off line under light power applications in search of better fuel mileage.

    The search for more internal combustion power throughout the 20th century was most often accomplished on either side of the combustion chamber. But to the true devotees of combustion science, much of the real magic happens in the combustion space above the piston. The Gen IV engines had proved to be excellent role models with regard to power, which of course predicated a goal toward increased efficiency. The next step toward increased fuel management was to move its point of entry from upstream of the intake valve to inside the combustion chamber. The acronym creators call this gasoline direct injection or GDI.

    This is not new science. Diesel engines have been perfecting this art for nearly as long as the internal combustion engine. Sprint Car engine builders have been doing this for decades. The key to GDI was to improve the combustion event with the goal of extracting more power from less fuel. The trick to injecting fuel into the combustion chamber is to do so at extreme pressures to ensure vaporization. This is exactly what the Gen V LT1 is all about. A high-pressure pump located just above the lifter valley generates pressures as high as 2,300 psi. The mechanical pump is driven off the camshaft and the fuel is shot directly into the center of the combustion space on top of the piston just after the intake valve closes.

    Not only does this precisely control the fuel to each cylinder but the direct injection also allows a higher compression ratio for the same octane, which has the mutually beneficial effect of improving fuel mileage while simultaneously increasing power. While the LT1 has garnered much of the attention as the engine for the Corvette and Camaro, GDI is also shared with the newest truck engines as well. The 5.3L L83 and the 6.2L L86 truck powerplants are not only all-aluminum torque beasts but also enjoy the benefits of GDI.

    A little-known fact about the L86 truck engine is that while its horsepower rating is down compared to the LT1, by merely installing the LT1 oil pan and intake manifold on this engine, you essentially have an LT1 as all other aspects, including the compression ratio, cylinder heads, and the camshaft as they are all the same. GM merely tuned the intake manifold to build more torque for the truck applications. So in the near future, it would pay dividends to keep an eye out for the L86 as another of the best deals in horsepower to come out of the small-block legacy.

    So while the Gen III LS1 is now 20 years old and has been usurped by its newer Gen V cousins, the foundation of pushrod, two-valve-per-cylinder performance is still as robust as ever. Let the other guys build their ultra-complex, dual overhead cam engines. The line still forms just behind the Gen V. It would be smart to check in with the LS movement every once in a while. It’s bound to change again soon and no doubt for the better.

    Power Numbers

    Engine Displ. HP TQ
    LS1, Gen III 5.7L, 346ci 350 365
    LS6, Gen III 5.7L, 346ci 405 400
    LS7, Gen III 7.0L, 427ci 505 470
    LS2, Gen IV 6.0L, 364ci 400
    LS3, Gen IV 6.2L, 376ci 430 425
    LS9, Gen IV* 6.2L, 376ci 638 604
    LSA, Gen IV* 6.2L, 376ci 556 551
    LT1, Gen V 6.2L, 376ci 460 465
    LT4, Gen V* 6.2L, 376ci 650 650
    *Supercharged

    Bore and Stroke Combinations

    Displacement Bore Stroke
    4.8L 293ci 3.78 3.26
    5.3L 325ci 3.78 3.62
    5.7L 346ci 3.89 3.62
    6.0L 364ci 4 3.62
    6.2L 376ci 4.065 3.62
    7.0L 427ci 4.125 4
    Compression Ratios

    Engine Compression
    Ratio
    LS1 10.25:1
    LS6 10.5:1
    LS2 10.9:1
    LS3 10.7:1
    LS7 11.0:1
    LT1 11.5:1
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    Dean Livermore of Hot Rods by Dean is shown fine-tuning our LS-powered Road Tour 1959 Chevy … and it’s still running strong having survived several Hot Rod Power Tours as well as a summer on the Road Tour. Amazingly reliable motor.
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    The fun with an LS and hot rodders is that you never know what you are going to get … “like a box of chocolates,” as the old movie line goes. How about a full set of Speedway Motors 9Super7 carbs on an Edelbrock intake manifold for this LS.
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    Here the LS used in our 1959 Chevy was set up by Shaver Engines topped off with an Inglese-stacked injection system.
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    Another mildly customized LS, this time again set up with an Inglese eight-stack EFI. Note coil packs were retained on top of the valve covers but hidden beneath faux valve covers.
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    This LT1 is the latest generation of what began as the LS1 in 1997. Now outfitted with gasoline direct injection (GDI) and more compression, the original LS1 made 350 hp while the current LT1 makes 460. Think you’d feel the difference?
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    This LS3 is topped off with a FAST LSXR intake; note coil packs are removed from the top of the valve covers and placed forward in the engine compartment on the frame.
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    We’ve had 20 years to perfect the LS engine swap and the move has become incredibly pervasive. This is an EROD LS swap into a G-body El Camino perfected by the guys at Holley.
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    Here is an LS3 as you may have received from Chevrolet Performance.
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    A quick way to spot a factory Gen IV LS engine is by the front-mounted cam sensor. Of course, it’s also very easy to swap one of these covers onto an earlier engine, as shown here on an iron 6.0L block so be vigilant.
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    This LS is all business, retaining stock coil pack location, Hooker exhaust manifolds, and FAST LSX intake.
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    How much better is GDI over multipoint fuel injection? A fair comparison would be to look at the horsepower and torque of the 6.2L LS3 versus the 6.2L LT1. It’s really not a fair fight since the LT1 (shown) has a full point more compression that helps it make 30 more horsepower and a shocking 40 lb-ft more torque.
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    We put the Chevrolet Performance crate engines to a dollar-per-horsepower test and the contest came down to a tie between the LS376 480 hp and LS376 515 hp versions of the LS3. The 480 hp version really makes 495 hp as an LS3 with a factory HOT cam with 0.525-inch lift. This is a carbureted engine.
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    Among the most significant changes in the LS series was the Gen IV configuration change to larger volume rectangle port cylinder heads elevated from the Gen III’s cathedral ports. This rectangle port configuration has been carried over to the Gen V with some minor changes.
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    The most significant change from Gen IV to V was the addition of gasoline direct injection (GDI). Fuel is now injected from a very high pressure mechanical pump located just underneath the intake manifold directly into the cylinders.
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    This shot of the combustion chamber reveals the location of the fuel injector located directly across from the spark plug. Extreme pressure means the fuel will be conditioned more accurately into smaller particles to burn more efficiently. The goal has always been to make more power with less fuel.
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    Among the improvements demanded by increased power, especially with superchargers, is additional cooling for the pistons. Engineers used small oil squirters located at the bottom of the cylinder to aim pressurized oil at the underside of the pistons to pull heat out of the crown. This was initiated with the LS7 and continued on the supercharged LT4.
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    If you’re looking for the big-daddy horsepower king-of-the-hill, look no further than the LS9. This engine can abuse the rear tires with 604 lb-ft of torque at 3,800 rpm and still spin the dials up to 638 hp at 6,500.
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    Crate engines have become the easiest way to bolt horsepower into almost any car with Gen V engines right at the top of the list. Making it even easier is the Connect and Cruise concept where with just a couple of part numbers you can order, for example, a 6.2L LT4 supercharged engine backed by either a four- or eight-speed automatic.
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    A Gen V move that has not received much attention is the power improvement gained by using E85 (85 percent ethanol) in a direct-injected engine. The L83 5.3L direct-injected Gen V truck engines are designed to run as Flex Fuel engines—especially with E85. With their GDI higher compression, Lingenfelter Performance testing gained 19 rwhp and 23 lb-ft of torque on a 2014 truck using E85.
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    The LS1 was the original Gen III engine. Displacing a mere 345 ci, it employed unique cathedral port heads, a 10.2:1 compression ratio, and a 0.470-inch lift hydraulic roller cam to make a reasonable 345 hp and 30 lb-ft of torque.
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    The LS6 was the first performance upgrade in 2001 with more compression (10.6:1) and a cam with 0.550-inch lift, and an improved intake that together bumped the power to 385 hp and 385 lb-ft of torque.
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    Major changes were afoot for the LS2 that fronted the evolution to Gen IV. The big news was a bump to a 4.00-inch bore increasing the displacement to 6.0L (364ci) and compression to 10.9:1 to make 400 hp and 400 lb-ft of torque.
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    GM raised the dissonance factor in 2005 when Corvette upped the ante by resurrecting the LS7 RPO for this all-aluminum 7.0L (427ci) spinner. As a crate engine, it still can hit the high notes with its normally aspirated 505 hp at 475 for torque.
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    In 2008, just a little over a decade after the LS1 debuted, Chevrolet decided size matters with a 6.2L (376ci) LS2 base engine for the Corvette with a 4.060-inch bore and big rec-port heads pushing 2.165-inch hollow-stem intake valves. Compression crept up to 10.7:1 along with power now at 430 hp and torque at 424 lb-ft.
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    The 2010 Camaro’s L99 6.2L engine differed only slightly from its LS3 cousin, adding Active Fuel Management (AFM) as well as variable valve timing (VVT) to deliver 400 hp and 410 for torque.
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    In the LS engine family hierarchy there can only be one king of the hill. Based on the LS3, the supercharged LS9 put a leg up on the rest of the clan with an Eaton 2.3L Eaton blower making 638 hp and 604 for torque all still from 6.2 liters. You can buy one straight out of the crate.
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    As a slightly detuned LS9, the ZL1 Camaro’s LSA supercharged 6.2L is no slouch. The LSA spins a smaller 1.9L TVS Eaton blower and claims 556 hp at 6,100 with 551 lb-ft of torque all the way down at 3,800 rpm. This engine too, is available as a wet sump crate package—ready to bolt right in.
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    In addition to straight production-based LS crate engines, Chevrolet Performance also offers enhanced versions of the LS3 like the LS376/515 that comes with a carbureted intake manifold and the ASA Hot cam. This punches the power up to 533 hp at 6,600 while pushing 477 lb-ft of torque at 5,200.
     
    Last edited: Oct 6, 2017

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