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Gen III and IV GM Small Block V-8 Engines - 4-Wheel & Off-Road Magazine

Gen III and IV GM Small Block V-8 Engines - Lego Engines Fred Williams Brand Manager, Petersen’s 4Wheel & Off Road gen Iii Iv V8 Engines engine Block Photo 12005777

There Was A Muscle Awakening under the hoods of General Motors' vehicles beginning with the '97 Corvettes, '98 Camaros, and '99-'03 pickup trucks. It was the start of the Generation III and IV V-8 engines (also known as the LS series), and the resulting powerplants have breathed horsepower numbers into the tried-and-true Chevy small-block that are so easily attainable it's silly. This new generation of fuel-injected V-8s is simple to build, easy to modify and swap into older 4x4s, and can be pushed to over 400 hp with simple computer upgrades. In fact, 500hp Gen IV engines are commonplace and 700-plus-horsepower crate engines based on this architecture aren't unheard of.

We spent a day at Turnkey Engine Supply assembling a Gen IV 6.0L LS2 and can honestly say we've seen Legos more complicated. In fact we're not sure why you wouldn't choose a Gen III or IV engine. Whether you are dragging one home from a junkyard or considering an all-new crate engine, when you learn how simple and powerful these engines can be and how plentiful they are, it's a no-brainer. Late-model Chevy small-block V-8s are as good as they've ever been, if not better.

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PhotosView Slideshow 1. We were at Turnkey Engine Supply to see the assembly of an LS2, which is an all-aluminum-block 6.0L (approximately 366 ci). These are available as either brand-new crate engines from Turnkey, or can be sourced from a junkyard Cadillac CTS-V, Chevrolet Corvette, SSR, TrailBlazer SS, and Pontiac GTO. The LS2 is similar in architecture to the complete line of Gen III and IV engines, including the common and inexpensive iron-block truck 4.8L, 5.3L, 5.7L, and 6.0L models. 2. The LS2 block is a four-bolt main style which means there are four bolts holding the main bearing caps of the crank. However, these engines are sometimes referred to as six-bolt mains due to the additional two side bolts which come in from the outside of the block for added block stiffness and low-end strength. Though the block is aluminum, the main caps are steel, which helps in the longevity of the engine. 3. The Gen III and IV engines do not use a distributor, but instead use a coil pack at each spark plug. This means the computer determines ignition timing as well as injection timing for each fuel injector. To monitor the stroke of the engine, a camshaft sensor picks up a signal off the camshaft in front of the LS2, while on the LS1 it is on the rear of the camshaft. There is also a crank position sensor that picks up a signal from a crank-mounted tone ring (be cautious of the LS2 from the '05 GTO as they have a different crank sensor from later LS2s). 4. The rods in these late-model engines are made of powdered metal and use a cracked metal design for alignment with the bearing caps. Made in a manner similar to both casting and forging, the metal powder is put in a mold, compressed, and then heat-treated. This process results in a strong lightweight part that uses less waste and ends up with a very uniform grain structure. Plus when the cracked cap design is used, the grain of the metal acts as an alignment grid to help fix and strengthen the rods. Turnkey uses these stock parts for most of its crate engines, but it does upgrade to forged pistons and ARP rod bolts to overcome some of the weaknesses of the original cast pistons. 5. The Gen III and IV oil pan is cast-aluminum with a reusable gasket, has dual windage trays to help against sloshing, and keeps oil near the pick up. A few different oil pans are available, but it is generally believed that the Camaro pan is better for off-roading. The truck pan is best for holding oil, but can also be too deep depending on suspension and hoodline layout. Most factory transmissions use a thick-cast lower torque-converter cover that ties into this oil pan for added strength, but we haven't found any aftermarket torque-converter covers that can be added to the older transmissions like the TH400 and TH350. If you know of any, please let us know as this could be a great upgrade component. 6. One notoriously bad feature of the LS engines is the lack of oiling when pointed nose-up on extreme angles. The guys from Twisted Customs have found an aftermarket steel oil pan that is similar in style to the Camaro pan, so that it doesn't hang down especially low, but it also has internal baffles and trap doors to keep feeding oil during steep climbs. PhotosView Slideshow 7. The factory roller lifters use plastic guide trays to keep lifters from spinning in place, yet make assembly quick. The head gasket is also made of multi layers of thin metal for a simple yet effective seal. The LS2 we built used the factory 243 casting aluminum heads outfitted with Manley intake valves, factory GM exhaust valves, and 190-psi valve springs. These heads are known to flow great and are held in place with 10 head bolts with five extra small bolts. 8. These engines use a molded plastic intake, but there are different styles depending on engine model. From left to right are: LS1, LS6 (LS6 has the inlet air-temp sensor on the side of the intake), truck intake (also known as an LQ9), LS2, and LS7. All the intakes are swappable except LS7. The LS7 uses a different mounting angle and has more square inlets compared to the more rectangular earlier engine, thus the LS7 and LS2 are referred to as Generation IV engines. One way to tell the intakes apart is the LS2 and LS7 have a 90mm throttle body with four mounting bolts while LS1, LS6, and truck intakes all use the 75mm throttle body with three mounting bolts. The LS2 and the LS7 intakes have the best airflow characteristics of the Gen III and IV engines, while the best torque ratings come from the truck (LQ9) intakes. 9. One benefit of the Turnkey crate engines is that the company changes all intakes to -6 fuel inlet lines. This is great for those swapping the engine into an older 4x4 since an aftermarket fuel system can be built. When assembling your fuel system it's recommended to run a fuel pump with 60-psi output to feed these fuel-injected engines. 10. The blocks have a bellhousing pattern nearly identical to the older classic Chevy V-8s. There is an extra bolt hole at the top of the block that many older transmission bellhousings do not have, and a hole on some older bellhousings like TH350 and TH400 at the 2 o'clock position that these blocks do not have. Some people add a tab to the bellhousing at the top to tie into the block, though most have found no issues with deleting these bolts. Many of the truck engines use an iron block whereas the LS1, LS2, LS6, and LS7 all come with aluminum blocks. However there is a new 6.2L truck engine known as an L92 that comes with an aluminum block. 11. In order to swap in the older transmissions, you may need this conversion flywheel kit that comes with all the mounting bolts, flywheel, and a spacer to attach the torque converter to the newer engine crank. There are also kits available to adapt a manual transmission to the back of these engines. 12. When junkyard scrounging, one difficult part to these engines is that block displacement identification can't be easily determined with the engine bolted to a transmission since the displacement casting is on the back of the engine. Here is "6.0L" cast into an aluminum block on the rear section of the block, so this means we are dealing with an LS2. If the casting were a 6.0, 4.8, or 5.3 in an iron block then it would be one of the truck engines, with the 6.0 being the most desirable for torque and performance. There is an aluminum block with 5.3L displacement from a Chevrolet TrailBlazer and Turnkey offers a 350hp version. An aluminum block with a 5.7 casting is either an LS1 or LS6, and a 7.0 casting in an aluminum block is the newer Gen IV LS7. 13. The Turnkey wiring harness is an easy way to swap an LS engine into your early-model truck or buggy. The harness comes ready to plug and play and simply requires 12V power, ignition, a tachometer, a fuel pump, and fans. The Delphi computer has been programmed with a Turnkey proprietary calibration and uses factory connectors for everything down to the electric fan controls. It is packaged in a marine-grade harness. 14. The harness plugs into the throttle positions sensor, idle air-temp sensor, MAP sensor, and idle air control on the intake as well as the knock sensor. The Turnkey engines use one knock sensor to tell the computer if the engine is detonating early and thus pulls timing. The truck, LS1, and LS6 blocks have knock sensors under the intake, while the LS2 and LS7 have them on the side of the block. 15. Four of the eight coil packs mount directly to the valve covers and are individual to each plug and cylinder. These negate the need for the classic distributor that mechanically distributes the spark to each plug. 16. When swapping the engine in place of an older Chevy V-8, you can simply use these motor mounts that bolt to the new engine mounting points but line up with the older-style motor mounts so the transmission doesn't need to be moved and the transfer-case location and driveshaft lengths can all stay the same. 17. Dealing with custom exhaust can be complicated with an engine swap, but there are many different manifolds and headers available for Gen III and IV blocks. Turnkey has both rear and center dump-block hugger units. 18. If you are really ready for some insanity under the hood, then give the guys at Turnkey a call. They have these engine available with packages including twin turbos and superchargers, not to mention custom cams and trick head work. If your checkbook can handle it, then power numbers between 330 and 775 hp are within reach. All engines are tested before they leave and can be rear-wheel-chassis dyno-tested once you have the engine installed if you want to bring your ride to the Oceanside, California, facility.

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