The pattern has always been the same. Car crafters take what the new car companies build and tweak these stockers to make even more power. The last big switch was when Chevy debuted the original small-block in 1955 and instantly antiquated every flathead engine ever built.
Fast forward to today and the third generation small-block. Technically, it's not even a small-block Chevy anymore, especially since the Gen III engine has found its way into far more applications than just Camaros and Corvettes. The LS6 that powers the CTS-V and the Escalade is also Gen III. Car crafters have taken to calling this engine the LS1 mainly because that was its first RPO (Regular Production Order) number used in the Corvette in 1997, various versions have sprouted from that original engine.
It didn't take GM Performance Parts (GMPP) long to realize that there was a market for a brand-new LS1 crate engine. While it has taken some time, this engine is unquestionably the leading GM performance small-block of the future. Virtually all the major performance magazines have dazzled the industry with exotic horsepower enhancements, conveniently avoiding the crucial information on how to set this engine up in a car and what you need to know in order to make this engine run. Plus, there are some very specific rules when it comes to making power modifications on these factory computer-controlled Gen III engines.
LS1 BasicsOur Project Light Speed will kick off a series of dyno tests we will perform on this GM Performance Parts LS1 engine, so the best place to start is with a quick overview of what you get when you step up for a GMPP LS1 crate engine. GM calls the LS1 a 5.7L engine, but in reality it's only 346 ci, but the good news is that it's packaged in an all-aluminum body that is more than 100 pounds lighter at 430 pounds than even an aluminum-headed Gen I small-block. With 10.25:1 compression and relatively small valves, the stock power ratings are generously deceiving. GMPP rates this engine at a net 325 hp with 330 lb-ft of torque. But our baseline testing revealed much more power at 402 hp and 398 lb-ft of torque employing the stock Corvette iron exhaust manifolds and a full 211/42-inch exhaust system with Flowmaster mufflers! But we're jumping ahead.
Our Project Light Speed LS1 came directly from GMPP dealer Scoggin-Dickey Performance Center in Lubbock, Texas. The engine comes with a complete factory wiring harness and computer, but you will have to also add a factory F-car mass airflow (MAF) sensor as well as a pair of oxygen sensors, and an adjustable aftermarket fuel pressure regulator to get the fuel properly pressurized.
Among these sensors, the most critical is the MAF. We used a GM '98-'00 F-car, 75mm sensor with a three-prong flat connector from Scoggin-Dickey that is designed to work with the program in the GM computer. We also employed the services of Steve Cole, owner of The Turbo Shop (TTS) in Compton, California. Cole has been working with Gen III engines almost from the day they debuted and has considerable experience with these engines. He says the MAF does much more than just measure air.
According to Cole, the factory system is tuned for a specific inlet tract leading up to and through the MAF. Any change to the stock system (such as a '00 Camaro, for example) will affect the amount of airflow into and through the MAF. This may not sound like a big deal, but the MAF also directly affects both the spark and fuel curves in the computer. This means that even a slight change to inlet air could place the computer in a different place on its fuel and spark maps, changing the tune-up.
As a further example, we quickly discovered that these engines are hard-wired to run at anywhere from 11.8:1 to 12.5:1 air/fuel ratio at wide-open throttle (WOT). This is much richer than the more accepted 12.8:1 to 13:1 range for a performance engine for peak power. GM does this to protect both the exhaust valves and the catalytic converter from heat damage. We attempted to reduce the fuel pressure at the regulator to lean out the engine, which at first worked quite well. However, after a few minutes of part-throttle operation and some further adjustments, the computer (using the feedback from the oxygen sensors) realized that the fuel delivery was now leaner and very quickly increased the injector pulse width to compensate. This also affected the WOT calibration and the engine went back to a 12.4:1 air/fuel ratio. What this means is that the only way to consistently change the engine to run leaner at WOT is to modify its programming with dedicated software tools such as EFI Live or the LS1 software editing system that TTS is currently perfecting.
Despite the rich air/fuel ratio, this LS1 is still a very impressive engine. Peak torque appears at a relatively low 4,300 rpm, giving this engine a broad power band up to its peak horsepower at 5,700 rpm. With the stock hydraulic roller cam's wide lobe separation angle, idle is dead smooth and throttle response is instantaneous. All of this contributes to an incredibly responsive engine that would be a blast to drive on the street.
These are just some of the things that we learned with the engine on the dyno for the first time. As we get deeper into this engine and do more modifications, there will be tons more information that we can deliver on how to modify and tweak these new Gen III engines. Next month we'll get into the exhaust side, and we can tell you now that the results are more than a little amazing. Suffice to say that the factory Corvette exhaust manifolds are plenty impressive. Stay tuned as we dive into the deep end of the Gen III small-block performance pool. C'mon in, the water's fine!
By The NumbersOur testing revealed the GMPP LS1 crate engine makes far more than GM's 345 hp catalog claim. As the numbers below indicate, this is a 400hp engine right out of the box!
TEST 1 RPM TQ HP BSFC 2,500 350 167 0.584 2,700 349 179 0.560 2,{{{900}}} 348 192 0.524 3,{{{100}}} 354 209 0.491 3,{{{300}}} 363 228 0.490 3,500 367 244 0.479 3,700 374 263 0.492 3,900 382 284 0.484 4,100 390 304 0.488 4,300 398 325 0.491 4,500 390 334 0.510 4,700 395 353 0.518 4,900 393 367 0.541 5,100 392 381 0.558 5,300 382 386 0.574 5,500 375 393 0.593 5,700 370 402 0.590 5,900 349 392 0.608 6,100 343 399 0.605 Avg. 372 305 0.535 Peak 398 402 0.479 Parts List Component Manufacturer PN LS1 crate engine GMPP 25534322 Oxygen sensor, {{{Corvette}}} GM 25312184 (2) Mass airflow sensor GM 25179711 Mufflers, 211/42-inch Flowmaster 952545 Fuel pressure regulator Aeromotive 13109The Tech StuffThis is a short overview of the LS1 crate engine supplied by GMPP as delivered.
Engine: 5.7 L (346 ci) PN, price: 25534322, $6,026 Scoggin-Dickey Power: 345 hp and 340 lb-ft of torque GM net power rating Bore x stroke: 3.98x3.{{{62}}} Block: All aluminum, six-bolt mains Crank: Nodular iron, rolled fillets Con rods: Powdered metal, 5.098-inch long Pistons: Cast aluminum, flat-top, 10:1 compression Cylinder heads: Aluminum, symmetrical port, 200cc intake port, 2.00/1.55-inch valves, 67cc chamber Camshaft: Hydraulic roller, 198/209 degrees duration @ 0.050, 0.500-inch valve lift, 116 degree lobe separation angle Rockers: Shaft roller rocker system, 1.7:1 ratio Intake: Composite, LS1/LS6 w/returnless fuel system Throttle-body: 75 mm Injectors: New compact design, 25 lb/hr at 58 psi MAF: {{{Camaro}}}/{{{Firebird}}} three-wire, 75 mm Ignition: Coil near plug, 6 amps primary current at 14 volts Exhaust: {{{Corvette}}} production, cast iron Electronics: Production GM ECU with "street rod" calibration