Nothing illustrates the power potential of a stroker Gen III/IV small-block better than a real-world engine strapped to the dyno. Thus far, the prior chapters have outlined how to select the myriad components necessary to assemble a stroker LSseries small-block. However, there are literally thousands of ways in which those components can be mixed and matched. Different horsepower goals, displacement targets, rules restrictions, budgets, and intended uses mean that diversity is just part of the engine-building game. Even so, some stroker combinations stand out from the crowd, due to their raw power output, simplicity, sheer size, low cost, or efficiency. This chapter lists several exceptionally designed LS stroker combinations, ranging from affordable street motors to 500-ci thumpers to all-out 9,600-rpm race engines.
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Full-Race Screamer LSX
Simply put, this 429-ci race engine is one of the meanest LS small-blocks ever built. Without the assistance of nitrous or forced induction, it kicks out a staggering 1,002 hp and 663 ft-lbs of torque. At 2.34 hp per ci, its specific output is right on par with that of a NASCAR Sprint Cup motor.
Built by the School of Automotive Machinists, the 429 powers a 3,500- pound 1999 Camaro down the quartermile in 8.52 seconds at 158 mph. Producing that kind of power in naturally aspirated trim requires a meticulously thought-out and executed combination that’s extreme in every regard. Based on a GMPP LSX block, the engine not only boasts a healthy dose of displacement, but it turns 9,600 rpm and breathes through a set of heavily massaged C5R cylinder heads that flow 430 cfm. To get the most out of those cfm, the 429 utilizes a Comp Cams 285/302- at-.050 solid roller cam that boasts nearly a full inch of valve lift. Obviously, this isn’t the kind of engine that will ever see street duty, as evidenced by its 7,500- to 9,600-rpm powerband. Because the Camaro that it powers is equipped with a Liberty’s clutchless 5-speed manual transmission, and the motor never turns less than 8,000 rpm at the track, the 429’s tight RPM band suits it perfectly.
Interestingly, SAM students and instructors built this monster small-block as part of a class project. The school operates one of the most respected vocational programs in the performance industry. Its unique curriculum covers short-block machining and assembly, cylinder head porting, CNC programming and operation, and race engine design. Between classes, SAM students work on the school’s various race cars, and they are actively involved in the design and testing process of engines, such as this 1,002- hp small-block. Many of SAM’s graduates go on to build race motors for some of the top names in racing, such as Hendrick Motorsports, John Force Racing, Warren Johnson Enterprises, Roush-Fenway Racing, McLaren Engines, and Honda IRL. For more information on SAM’s unique program, visit www.samracing.com.
Wee Beast LS1
In the realm of stroker Gen III/IV small-blocks, a 383-ci motor is a bit on the small side. Proving that a well-executed parts combination can sometimes overcome a displacement handicap, this 383 produces horsepower and torque figures on par with those of many 408- and 427-ci stroker motors, all while burning 91- octane pump gas. It churns out 535 hp and 508 ft-lbs of torque on a Dynojet chassis dyno. Using the accepted figure of 15-percent drivetrain power loss, that equates to roughly 629 hp and 598 ft-lbs of torque. Trying to extrapolate horsepower at the crankshaft from rear-wheel horsepower isn’t an exact science, but, needless to say, this 383 is one stout package (designed and built by Tony Mamo of Airflow Research).
It’s equipped with an Eagle crank and rods, Wiseco 11.35:1 pistons, lightly ported Air Flow Research 205-cc cylinder heads, and a mild Comp Cams 234/238- at-.050 hydraulic roller camshaft. Peak horsepower figures aside, what makes this 383 truly impressive is its broad powerband. It produces nearly 550 ft-lbs of torque at 4,000 rpm, and it carries most of it through the entire RPM range. This kind of low- and mid-range torque makes for an outstanding street/strip motor with explosive throttle response at all RPM.
For enthusiasts on a tight budget, a 383 makes a lot of sense, as the largest bore a 5.7L aluminum or 5.3L iron block can handle is approximately 3.905 inches. When you match that bore size with a 4.000-inch crank that requires minimal clearancing, the end product is an easy-tobuild and affordable 383-ci short-block. As this wee beast illustrates, big performance can come in small packages.
Big Daddy LS2
There was a time when even bigblocks couldn’t crack 500 ci, but now small-blocks can reach that massive displacement total. Add that to the astounding airflow potential of the Gen III/IV cylinder heads, and it’s a match made in horsepower heaven. Few engine combinations illustrate the benefits of massive cubic inches better than the SAM 500-ci LS2 small-block.
It’s based on an ERL Super Deck II block that boasts a towering 10.200-inch deck height, and it can accommodate a 4.500-inch Callies stroker crank. When that’s combined with Darton sleeves that allow for a 4.202-inch bore, the result is a 500-ci monster. To feed all those hungry cubes, the LS2 relies on a stock LS7 intake manifold and a set of ported LS7 cylinder heads that flow 390 cfm. Actuating the valves is a modestly sized Comp Cams 248/254-at-.050 hydraulic roller cam that many people would consider conservative in an engine 50 ci smaller.
As no surprise, SAM’s 500-ci LS2 produces an incredibly stout torque curve that peaks at 630 ft-lbs at 5,100 rpm. Even more impressive is the fact that the 500 dishes out 600-or-more ft-lbs of torque from 4,500 to 6,200 rpm. Of course, torque is useless without horsepower, and the 500 doesn’t disappoint in that department, either. The motor posts a total of 717 hp, thanks to its generous displacement, and peak power arrives at a leisurely 6,500 rpm. If the same heads and camshaft were installed on a 427, it would have to turn at least 500 rpm more to produce the same peak horsepower.
As with all of its project engines, the SAM 500 was put through its paces at the race track. Installed in the school’s 1998 Camaro project car, the motor was good for a 9.96-at-135-mph pass in the quarter-mile. That’s not too shabby at all for a 3,700-pound car running on 93-octane pump gas.
Welterweight Brawler LS3
Measuring right in the middle of the displacement spectrum, this 417-ci smallblock strikes a sweet balance of affordability and size. By pairing a factory 6.2L aluminum block’s 4.065-inch bore— cleanup-honed to 4.071 inches—with a 4.000-inch stroke, the result is a healthy dose of displacement without the need for a costly re-sleeving procedure. For hot rodders looking to build a budget-priced aluminum Gen III/IV motor without breaking the bank, the 417 is an extremely popular displacement combination. This particular 417 (designed and built by Tony Mamo of Airflow Research) ups the ante with a Compstar rotating assembly and a heavy-breathing top end comprised of AFR 230-cc cylinder heads and a FAST 102-mm intake manifold and throttle body. When they’re all matched with a Comp Cams 243/247-at-.050 hydraulic roller cam, the result is 663 hp and 579 ft-lbs of torque on 91-octane pump gas.
Peak output, however, is the least impressive aspect of this potent combination. The 417 produces more than 500 ft-lbs of torque from 3,400 to 6,900 rpm. Furthermore, the 417 kicks out more than 570 ft-lbs from 4,600 to 5,900 rpm, and it peaks 579 ft-lbs at 5,500 rpm. The beauty of a highly optimized combination like this is that it combines outstanding peak horsepower with an incredibly flexible torque curve. That means it will pull all the way to 7,000 rpm when called upon, yet easily roast the hides anywhere in the low- and mid-RPM range. Further enhancing its street credentials, the 417 idles smoothly at 900 rpm, and it also boasts a hydraulic roller cam valvetrain that requires minimal maintenance. With its blend of power and streetability, the 417 treads on turf that only big-blocks could touch just a few years ago.
Brazilian Stock Car LS3 Motor
A budget race engine is somewhat of an oxymoron, but Mast Motorsports’ 416-ci LS3 is the exception to the rule. Because the engine had to be designed and built as a spec motor for Brazil’s Copa Nextel stock car road racing series, Mast had to stick with a strict $15,000 budget. Making the task that much more difficult, the motor has to last for a full 12-race season, which equates to roughly 2,800 hard racing miles. Nonetheless, the 416 produces 617 hp and 568 ft-lbs of torque.
To pull off this impressive feat of dollar-stretching performance and durability, Mast relies heavily upon production GM components. A testament to the race-bred nature of modern LS-series small-blocks, the Mast 416 utilizes a factory 6.2L aluminum block, finish-honed to 4.070 inches, and a stock LS3 intake manifold, throttle body, and cylinder heads. With a mild 240/256-at-.050 hydraulic roller cam actuating the valves, the 416 produces peak power at a modest 6,300 rpm, which greatly improves overall engine durability. Holding the short-block together are a Compstar 4.000-inch forged crank and rods and Mahle 11.3:1 pistons.
In contrast to the high-octane gasoline used in NASCAR Sprint Cup engines, the Brazilian Copa Nextel stock car series mandates an E98 fuel that’s 98 percent ethanol. Interestingly, the Mast 416 produced an additional 26 hp (617 vs. 591) on ethanol compared to 93- octane gasoline. Although ethanol has less BTUs of energy than gasoline, Mast says that its greater heat of vaporization enables it to pack a denser air/fuel mixture into the cylinders for an increase in power. The downside is that it takes 1.5 times as much ethanol to make similar power as gasoline, dramatically reducing fuel mileage. Nonetheless, considering that this 416 is a bona-fide race engine, the fact that it’s based heavily on production GM components is simply amazing.
Written by Barry Kluczyk and Posted with Permission of CarTechBooks
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