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What Makes the LS Engines So Great?

The Gearhead Grind

Evan Perkins Jan 8, 2016 0 Comment(s)
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Are you suffering from an overdose of LS engines? If so, we get it. Those things are everywhere! In the last 10 years, the LS market has absolutely exploded and we now see them nestled between the fenders of everything from show cars to all-out racing machines. As their price point descends even further, and as the aftermarket continues to make their transplant into all varieties of vehicles easier and easier, naysayers will have to come to terms with the fact that they are simply not going away.

So, whether you are still suspect of new technology or ready and raring to drop an LS powerplant into your ride, I thought it would be neat to give you a little background from an engineering standpoint of what has lead to the overwhelming proliferation of LS engines in hot rod culture.

An engine is just an air pump, right? Air goes in, fuel is added, stuff blows up … horsepower happens. Right? We’ve all heard some form of that adage but, in reality, there’s a heckuva lot more going on in there than that. And, the LS engine series combines a host of modern technological advances to optimize internal engine efficiency.

For starters, the pistons are of a hypereutectic alloy that is much stronger and more thermally stable than the cast pistons used in Gen I small-blocks. The aforementioned thermal stability allows the pistons to be installed with less piston-to-wall clearance, which reduces wear and helps bore sealing. Also, the pistons are fitted with a thinner, metric ring pack that not only reduces friction and blow-by, but also, again, helps bore sealing.

Moving down the line, the connecting rods used in LS platforms are of a powder-forged design. They have a cracked cap that—by means of an irregular mating surface—allows the rod cap to align precisely with the big-end, helping equalize bearing wear, and they are far stronger than production rods from earlier engine architectures.

The production LS crankshafts are tough pieces with relocated thrust bearings (now in the middle of the block) and have been proven durable to near quadruple-digit horsepower outputs.

The real shining star of the LS bottom end is the six-bolt main caps. While early LS1s necessitated the additional cap fasteners to hold the somewhat-flexible block in shape, the later LS3 and iron LS platforms were catapulted to god-like status thanks to the Herculean strength of the rigid bottom-end design. The best part, all LS engines offer the six-bolt cap configuration. No more searching for a four-bolt block or machining a two-bolt block for aftermarket mains.

So, we’ve established that the bottom end of an LS engine has got quite a few things going for it over traditional small-blocks—from the factory anyway. But, if that was the only improvement we would have never seen the wave of LS-swappery that we have. After all, the old-school small-block has the most abundant aftermarket of any engine platform ever produced. And why change up your whole SBC engine combo for a little more strength when an aftermarket bottom end is under $1,000? It just doesn’t make sense. Unless, of course, that engine comes with the single best Chevrolet top end design ever conceived. Then the stars begin to align.

The real pièce de résistance of the LS family is the cylinder head and valvetrain components. In a nutshell, this is what allows them to make obscene power with very little modification. The heads come right out of the factory with a 15-degree valve angle. Price out a 15-degree small-block head and you’ll see why that is such a big win for the LS. In addition to improved valve geometry, the LS line has replicated ports—gone are the Gen I’s mirrored port configuration that had different runner sizing for cylinders 3 and 5, and 4 and 6. The new style allows every runner to be symmetrical, and as such, gives every cylinder an equal opportunity for airflow. A stock-ish LS head flows in the neighborhood of 250-280 cfm—with exceptional low-lift flow—that is well into the territory of pricey aftermarket small-block heads. Ported stock LS heads have been proven to move over 300 cfm of air, and guess what, they are already aluminum!

The valvetrain design for the Gen III-IV engines retains the pushrods we hold so dear, but also remedies all of the high-rpm instabilities associated with older-style, stud-mounted rockers. LS rockers are still stud mounted but are much more stable thanks to a rocker cradle, and also offer a 1.7:1 ratio (compared to the 1.46:1 of its older relatives). No more pinning rocker studs, machining for screw-in studs, or adding rocker girdles. The LS valvetrain is 7,000-rpm capable right out of the gate. GM also incorporated beehive springs, which reduce valvetrain mass, and increased the base circle diameter of the camshaft to prevent core flex and allows for more aggressive lobe profiles. Oh, did we mention all LS engines have factory-equipped roller lifters? We can show you hundreds of dyno tests that verify just how beneficial roller cams are, and with the LS, there’s no need to spend $1,000 on a retrofit kit.

I could go on and on … but at this point you probably get the point. Those LS engines are good stuff. But, if you’re hanging on to your first-gen small-block with a death grip, not yet ready to make the jump, that’s just fine. Knowing that there is something better out there doesn’t diminish the things we love one bit.

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