GM Performance Parts Crate Engines Tested - The Smoking Gun

Over 2,200-Horsepower Worth Of GMPP Crate Engines Tested On The Milford Proving Grounds

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If you are a fan of late-model GM vehicles then no doubt-like me-you have dreamed of burning up the Milford Proving Grounds in one of GM's test vehicles. A location so remote and top secret that it is guarded like Fort Knox, and civilians (like us) aren't permitted to even walk around unsupervised. Matter of fact, I was almost surprised I was able to get my camera equipment back through security on the way out. While there are a few tangible things (that can't be mentioned) lurking around in plain site, the most impressive secrets are just under the surface of the many ordinary looking production vehicles sitting on or driving around the 4,000-acre property. On this particular occasion, though, GMHTP was one of only three media outlets to be given access to the holy land to view and drive the most extraordinary looking vehicles on the premises-GM Performance Parts' collection of hot rods.

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Dr. Jamie Meyer of GMPP was very proud to show off several well-constructed platforms in which to showcase its catalogue of LS crate engines, all built in-house. The shop in which GM Performance Division Project Manager Mike Copeland works would be a dream for any builder, with access to any machine or tool you can think of, plus all sorts of CAD and engineering software. However, Mr. Copeland assured us that your typical hot rodder could supplant the E-ROD package-especially in a Tri-Five like the '55 that GMPP lifted from the GM Heritage Center. For those not familiar, the E-ROD package is an emissions-compliant engine (LS3 in this case) that comes with all of the necessary components including a wiring harness, calibrated ECM, exhaust manifolds, catalytic converters, O2 sensors, etc. GMPP expects that possibly by the time you read this the California Air Resource Board (CARB) will have certified the package for use in any vehicle from 1995 or earlier, which of course can be modified by any CARB-approved product for further power increases without losing compliance. Currently the E-ROD comes in four variations: LS3 for automatic transmissions (PN 19244805), LS3 for manual trans (PN 19256487), 5.3L for automatic trans (PN 19256513), and 5.3L for manual trans (PN 19256517). However, GMPP has announced that it fully intends to release a 505-horse LS7 and a 550-horse LSA version.

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In a pretty light car, such as GMPP's '55, the 430 horsepower factory LS3 is a potent powerplant-as any Corvette owner can tell you. A great blend of torque off the line and top-end power, which performed flawlessly on Milford's straight. The tall First gear in the GMPP 4L65E trans combined with a set of 4.10 gears, aided by an Eaton posi, stuffed in an S-10's 7.5-inch 10-bolt helps get the two-door off the line in a hurry. This was the least powerful of the group tested, but the most surprising. Saginaw power steering kept the wheel feeling light with larger sway bars, Eaton springs and Monroe shocks all around plus 2-inch drop spindles up front that also gave the impression that this car liked to be thrown around. Of course a set of BFG G-Force T/A tires (235/50R18 front, 245/55R18 rear) also aided substantially in its handling. One of the many trick features designer Dave Ross came up with for the '55, facilitated by Copeland and Jim LaFontaine, was the use of 18x7.5 steel wheels off the (base) 2010 Camaro with custom center caps. The build team moved the centers back 1.250-inches to make it happen, and the rears were widened to 8.5 inches. The large wheels allowed for a set of C4 disc brakes at all four corners to match the LS3's acceleration capabilities.

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The E-ROD '55 is all-together a great build, which uses mostly parts from the GMPP catalogue. Copeland assured us that few custom parts were required to complete the build, most of which were used just to give it a unique touch. Custom-bent 2.5-inch dual exhaust was one such example, for assured fitment, that used Dynomax mufflers to give a subdued yet muscular tone. CARS Inc., supplied the interior including the upholstery with a pattern lifted from the '55 Bel Air convertible. The Bow Tie emblems were replaced with 2010 GM design pieces, and the PPG waterborne paint was custom mixed to Ross' liking. The original body is intact as are the stainless steel moldings, which have been polished.

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GMPP's LSX454-equipped '89 Camaro is more-or-less the opposite end of the spectrum. This hard charging test mule is a lot less refined, but offered more visceral thrill. It has been a long-standing test car for many products, and came equipped with a number of goodies including a rollbar, race seats, and harnesses. Some clutch issues prevented us from really roasting the hides, but with 600 lb-ft of torque that can happen. With the factory LS7 manifold in which it is equipped, the 454-cubic-inch mill is rated at 580 horsepower, though, with a carburetor and the GMPP single plane intake it has made 620. [Check out the high-tech build-up of this motor later in the story.] GMPP's flywheel (PN 24240678) and accessory drive (PN 19155067) were an easy fit to supplant the motor, however, they do not have a specific harness and controller, so the LS3 pieces (PN 19201861) were used with some modification. A custom tune was needed for the healthy 236/246-duration cam, which utilized a mass air sensor incorporated into a custom-bent cold-air intake tube. Of course there were plenty of odds and ends also needed like a set of factory coils, starter, and a T56 trans; but Copeland said this swap was pretty straightforward for the most part. You've seen plenty of third-gen LS1 swaps on the pages of GMHTP, so this shouldn't come as much surprise.

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Cramming a GMPP LSA into a '96 Impala, on the other hand, was a bit more involved in terms of the electronics, fuel system, and accessory drive. An accessory drive kit is offered by GMPP (PN 19243525), as well as an A/C add-on kit (PN 19244106), which is particular to the LSA motor. If this kit fits, then all is well, but if not the user will be forced to do some fabrication as there is currently little to no aftermarket support. The blown, 556-horse motor also requires quite a bit of fuel, so a high-pressure, high-flow system is a must. An Aeromotive A1000 pump was used on the Impy after a 255-lph in-tank pump proved it couldn't keep up. Like the LSX454, the LSA uses an eight-bolt flywheel or flexplate (PN 12622564), which is available through GMPP and will bolt up to any LS-compatible converter and trans. Another issue was the lack of an LSA-specific harness and controller so, just like with the LSX454, an LS3 harness and controller had to be adapted and tuned for its new use. It should be just a matter of time, though, before these pieces are available from GMPP. Copeland says the LSA swap is definitely for the more experienced builder.

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Unfortunately the Impala's weight took some of the zip out of the LSA, which is backed by GMPP's toughest automatic [the 4L85E], but of course 551 lb-ft of torque is still more than enough to break the tires loose at will. The Impy was by far the most comfortable of GMPP's collection. If I had a choice of which car I'd be driving on the Hot Rod Power Tour it would be the Impy for sure. With the comfort of this sizeable sedan, the LSA's smooth operation and ample power for passing on the highway, it's the quintessential cruiser. Conversely, turning the key in the LS9-powered '99 Camaro is like powering up a Pegasus rocket. As smooth as the 638hp LS9 may be, it is an engine that begs to be driven hard-especially in a light and agile chassis like a fourth-gen. The GMPP boost gauge seemed to mock me from the A-pillar every time I started to squeeze on the throttle-daring me to bring the needle up to 10.5 psi while watching my life flash before my eyes in a blur of tire smoke and disapproving looks from GM's security crew. Winding out the first three gears (of the refreshed T56) at full throttle is an exercise in intestinal fortitude. We had the opportunity to also take a ride in a ZR1, which provided the same visceral thrill-though with several hundred pounds less to hold it back.

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As you may remember from our February '07 issue, GMPP has proven that with a little know-how it is definitely possibly to cram a dry-sump LS7 into a fourth-gen. However, many doubted that the raised height from an LS9 supercharger would fit under the cowl and Copeland was destined to prove them wrong, though he later concluded that this swap is only for very experienced builders. After some careful consideration, the decision was made to place 47mm spacers in-between the BMR K-member and the chassis. This gave the necessary clearance needed for the blower without having to cut the cowl significantly, or having a negative effect on suspension geometry according to Copeland. The engine mounts were modified to lower the engine 5 mm as well, and 15mm spacers were used between the cradle and trans crossmember. Another issue unique to the LS9 was its huge fuel demands, which (just like the Impala) was remedied with an Aeromotive A1000 pump, regulator, and new feed lines-using the stock lines as a return (converting to a return-style system). Helping to determine just how much fuel the blown 6.2L would require is an LS9 MAF built into a tube to connect the throttle body to the stock airlid, made from a Duramax air cleaner. It was plugged into a modified LS3 harness and ECM.

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The accessory drive is another challenge due to a lack of aftermarket support on the fourth-gen, GMPP had to modify the factory pieces (PN 19243524)-locating the alternator lower left below the power steering, using the same belt to spin the A/C and power steering pump. The LS9 also has a unique nine-bolt flywheel (PN 12598613), with no flexplates available, that could make mating it to anything other than a T56 or TR-6060 difficult. Just like with the LS7, the battery was relocated to the trunk to make room for the dry-sump oil tank. In fact, GMPP actually used the same '99 test mule from its LS7 adventure, but gave it a completely new face. A modified set of ZR1 front wheels allowed for some sticky Michellin Pilot Sports, and the flat black paint scheme was traded for a more appropriate Jetstream Blue. The interior was overhauled with factory tan leather seats and carpet as well as GMPP's line of gauges placed into a custom dashpanel. Other parts from the previous build were carried over such as the Kooks 1 7/8-inch long-tubes, MagnaFlow catback, Strange S60 rear, and BMR torque arm.

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While the world's first and only LS9 fourth-gen was, of course, the crown jewel of the collection, I have to admit this lover of late-models started to picture himself cruising the streets of Tampa or L.A. in an LS-powered Tri-Five after some seat time in the E-ROD '55. In any event, all of GMPP's crate engines proved potent performers with plenty of potential no matter what platform you chose to apply it. Best of all, each crate engine has a level of refinement and a warranty that only an OE can provide. Yes, I said warranty-24 months or 50,000-miles (whichever comes first) of worry-free enjoyment can be had, which is something you won't find anywhere else in the hot rod industry. If you are wondering how GMPP manages such an incredible warranty on even the LSX454, then check out the incredible technology and level of quality control that goes into building each one of these engines.

Supercharged LS9
Car: '99 Camaro Z28
Block: 319-T5 aluminum with iron sleeves, 376 cid (6.2L)
Bore x Stroke (in): 4.060 x 3.620
Crankshaft: Forged steel
Connecting Rods: Forged titanium
Pistons: Forged aluminum
Camshaft: Hydraulic roller, 211/230 duration, 0.562/0.558-inch
Cylinder Heads: LS9 356-T6 aluminum, CNC ported, 2.160 titanium intake, 1.590 hollow stem/sodium filled exhaust valves
Compression Ratio: 9.1:1
Redline: 6,600 rpm
HP/TQ: 638/604

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LSX 454
Car: '89 Camaro
Block: Iron, 454 cid (7.4L)
Bore x Stroke (in): 4.185 x 4.125
Crankshaft: Forged steel (4340)
Connecting Rods: Forged steel (4340)
Pistons: Forged aluminum
Camshaft: Hydraulic roller, 236/246 duration, 0.635/0.635-inch
Cylinder Heads: LSX-LS7 aluminum, 2.20 titanium intake, 1.610 hollow stem/sodium filled exhaust valves
Compression Ratio: 11.0:1
Redline: 6,500 rpm
HP/TQ: 580/600 (with factory LS7 intake)

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Supercharged LSA
Car: '96 Impala SS
Block: Aluminum, 376 cid (6.2L)
Bore x Stroke (in): 4.060 x 3.620
Crankshaft: Forged steel
Connecting Rods: Powdered metal
Pistons: Hypereutectic aluminum
Camshaft: Hydraulic roller, 198/216 duration, 0.492/0.480-inch
Cylinder Heads: LSA 356-T6 aluminum, 2.160 steel intake, 1.590 exhaust valves
Compression Ratio: 9.1:1
Redline: 6,600 rpm
HP/TQ: 556/551

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Car: '55 Chevy
Block: Aluminum, 376 cid (6.2L)
Bore x Stroke (in): 4.060 x 3.620
Crankshaft: Nodular iron
Connecting Rods: Powdered metal
Pistons: Hypereutectic aluminum
Camshaft: Hydraulic roller, 204/211 duration, 0.551/0.522-inch
Cylinder Heads: LS3 aluminum, 2.165 hollow stem intake, 1.590 exhaust valves
Compression Ratio: 10.7:1
Redline: 6,600 rpm
HP/TQ: 430/424

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LSX 454: Big Block Small-Block
With so many custom engine builders out there, you may be wondering why you should consider purchasing a GMPP LSX454 crate motor. To find out, I headed over to the GMPP plant in Livonia, Michigan, where the 620hp capable LSX454s are assembled. An extremely thorough and efficient assembly program manages to produce a reliable and consistent product worthy of its name. LSX Engineer Rocko Parker was instrumental in developing this program, and setting the standards to which these motors are assembled. Rocko and the fine crew at the plant walked us through the process to show us where they get the confidence to put such a hefty warranty on their product.


Chevrolet Performance Parts
Detroit, MI 48232


Engines Drivetrain
Over 2,200-Horsepower Worth Of GMPP Crate Engines Tested On The Milford Proving Grounds
Oct 19, 2010


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