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We add a ProCharger D-1SC supercharger to our LSX376-B8 crate engine

The Great B8 Plus: We take a blower-ready crate engine rated for 8 psi and figure out how to stuff in just a bit more

Richard Holdener Mar 30, 2018
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Why do we love Chevrolet Performance crate engines? The answer is easy; GM has done most of the hard work already. Don’t get us wrong, we like a good engine build as much as the next guy but there is just something about a complete engine (or nearly so) showing up in a crate ready to rock. Take, for example, the LSX376-B8. In addition to being a complete long-block (minus the oil pan and induction system), the Chevrolet Performance unit was a known quantity. Unlike many builds where you find out if it runs, if it leaks oil and, ultimately, what kind of power it makes the first time it runs on the dyno, the Chevrolet Performance crate engine was tried, true, and tested. If you put an oil pan and stock intake on this thing it will make what every version of this crate engine makes when it gets tested. Having something you can count on is reassuring, but it also has the potential to provide a definitive starting point for upgrades. Such was the case in our Great B8 adventure, as the boost-ready crate engine was given a few tweaks before being subjecting to forced induction.

Before we start in with the modifications and boost we should take a look at what the LSX376-B8 came standard with. A little brother to the B15 version, the B8, in GM’s words, “is designed for lower-boost applications, up to about 8 pounds. That’s suitable for most supercharger and turbo kits that are designed to be used with production-based applications.” You can guess what the 15 in the B15 version stands for. That’s right, up to 15 psi. Having run over 25 psi on a B15, we were confident that the B8 version was safe well past the recommended 8 psi. Despite the lower boost rating, the LSX376-B8 featured a number of desirable specifications, including an iron LSX block filled with 9.0:1-compression forged aluminum pistons. The boost-ready short-block received a factory LS3 (non-supercharged) cam and free-flowing, rectangular port LS3 aluminum cylinder heads. According to GM, if this combination were to be completed with a factory LS3 intake, throttle body, and oiling system (not included with the crate engine), the LSX376-B8 should produce near 475 hp. Ours produced 468 hp and 465 lb-ft of torque with a FAST LSXR intake and 102mm throttle body. Those numbers are well within the margin of dyno variance. Before heading back to the Westech Performance dyno we added a Holley oil pan and ARP head studs to better withstand the boost we had planned.

After a quick dyno verification of what we already knew, we set out to make the necessary changes for more power. First on the list was a cam change. The mild, naturally aspirated cam works okay with a blower but—like most LS applications—there was plenty of power to be found with a cam upgrade. Knowing the ProCharger centrifugal supercharger works best with a cam designed specifically for that application, we gave Comp Cams a call. They supplied a 277LCB HR14 designed for an LS equipped with a centrifugal supercharger. The blower cam offered a 0.614/0.624-inch lift split, a 227/243-degree duration split, and a 114-degree LSA, compared to the 0.551/0.552-inch lift split, 204/211-degree duration split, and 117.5-degree LSA for the factory cam.

We teamed the cam with both a valvespring and pushrod upgrade. To work with the cam, Comp Cams supplied a dual valvespring kit (PN 26526TS-KIT) that provided the necessary coil-bind clearance and rpm potential. The stock pushrods were ditched in favor of a set of hardened (stock length) versions from Comp. The three-bolt cam swap required the use of a dedicated three-bolt GM cam gear. After the valvetrain upgrades, the LSX376-B8 produced 532 hp and 492 lb-ft of torque in naturally aspirated form (a gain of 64 hp and 27 lb-ft).

After the cam swap, it was time for some boost. For the modified B8, a ProCharger D-1SC centrifugal supercharger would supply the boost. Capable of supporting 1,000 hp on the right combination, the limiting factor on this crate engine would not be the supercharger but rather the 65-pound FAST injectors. Given the street-driven nature of the build, we hardly think 1,000 hp is necessary, or even useful, on the street. Consider the injector choice a reality check to provide some much needed common sense. To keep the charge temperatures down, the ProCharger D-1SC was teamed with a matching air-to-air intercooler (high-flow upgrade).

Running a 4.25-inch blower pulley and 7.65-inch crank pulley, the combination produced a peak boost pressure of 13.6 psi at 6,400 rpm, which is where the 65-pound injectors maxed out. The result was 878 hp and 748 lb-ft of torque; more than we expected from the 8-psi–rated crate engine. There was more power to be had with either more engine speed and/or with a pulley swap, but what’s the point. Does a street car really need over 850 hp? We’ve done some stupid things in awesome LS-powered cars making only 500 hp. We shudder to think of how much trouble we can get in with an extra 350 hp! Thanks to some minor mods and boost, this ProCharged Chevrolet Performance crate is officially the Great B8+!

002 B8 Chevrolet Performanec Crate ProCharger 2/21

1. Though lacking the forged crank and rods of the more potent LSX376-B15, the LSX376-B8 (PN 19332312) is a solid foundation for any boost build.

003 B8 Chevrolet Performanec Crate ProCharger 3/21

2. An iron LSX block ensured enough strength for almost any boost level. The block was teamed with a cast crank, powdered metal rods, and forged pistons.

004 B8 Chevrolet Performanec Crate ProCharger 4/21

3. Ensuring plenty of power potential was a set of 0821 rectangular port (LS3) heads. With flow figures reaching 315 cfm, these heads will support serious power levels even before adding boost.

005 B8 Chevrolet Performanec Crate ProCharger 5/21

4. The LSX376-B8 has a lot in common with an LS3 crate engine, including its camshaft and valvesprings.

006 B8 Chevrolet Performanec Crate ProCharger 6/21

5. One upgrade that happens with the LSX376-B15 crate engine is that you get six-bolt heads to better keep the cylinder heads in place under higher boost levels. We decided to ditch the factory torque-to-yield head bolts for a set of high-strength head studs from ARP. By doing this simple upgrade our LSX376-B8 should be able to handle quite a bit more boost.

007 B8 Chevrolet Performanec Crate ProCharger 7/21

6. The LSX376-B8 ships without an oil pan so we opted for a Holley LS swap pan (PN 302-2BK) fitted with their upgraded trap door baffle insert (PN 302-11). We also dressed the engine in stainless hardware from an ARP accessory bolt kit (PN 534-9605).

008 B8 Chevrolet Performanec Crate ProCharger 8/21

7. To finish out the engine, we added a bulletproof ATI Super Damper, FAST LSXR intake and 102mm throttle body, and a Holley HP ECU to make it run. For headers we used Hooker 1 7/8-inch-long tubes. The low-compression LSX376-B8 crate engine produced 468 hp at 5,700 rpm and 465 lb-ft of torque at 4,500 rpm.

009 B8 Chevrolet Performanec Crate ProCharger 9/21

8. After running with the supplied single-bolt LS3 cam it was replaced by a healthier version from Comp Cams, so we pulled the timing cover to get to the goods.

010 B8 Chevrolet Performanec Crate ProCharger 10/21

9. The more aggressive blower cam featured a 0.614/0.624-inch lift split, a 227/243-degree duration split, and a 114-degree LSA. This cam is specifically designed to work with a centrifugal supercharger like the ProCharger D-1SC we had sitting on deck.

011 B8 Chevrolet Performanec Crate ProCharger 11/21

10. Note the use of the three-bolt cam, which we typically prefer to the single-bolt design. The LSX block uses a unique cam retention plate.

012 B8 Chevrolet Performanec Crate ProCharger 12/21

11. The three-bolt cam required the use of a matching three-bolt, 4X cam sprocket (PN 12586481). We decided to retain the LS3-style spring-loaded chain tensioner.

013 B8 Chevrolet Performanec Crate ProCharger 13/21

12. The stock blue valvesprings were too soft for our new, more aggressive cam so an upgrade was needed. This nifty valvespring tool was used to compress the factory LS3 springs.

014 B8 Chevrolet Performanec Crate ProCharger 14/21

13. The tool made short work of the dual-spring installation. The dual valvespring kit (PN 26526TS-KIT) from Comp included tool steel retainers along with new locks and seals.

015 B8 Chevrolet Performanec Crate ProCharger 15/21

14. The new valvesprings all but necessitated a pushrod upgrade. The stock pushrods were replaced by a set of hardened (0.080-wall) 7.400-inch pushrods from Comp.

016 B8 Chevrolet Performanec Crate ProCharger 16/21

15. Run on the dyno with the new camshaft, the LSX376-B8 crate engine produced 532 hp at 6,400 rpm and 492 lb-ft of torque at 5,200 rpm. The cam swap was worth 64 hp and 27 lb-ft on the naturally aspirated, low-compression LSX376-B8 crate engine. This just goes to show how tame the factory cam was.

017 B8 Chevrolet Performanec Crate ProCharger 17/21

16. The cam swap netted power gains through the entire rev range; always a good sign that you made the right cam choice. The fact that this cam was designed for a blower makes the gains in naturally aspirated form even more impressive.

018 B8 Chevrolet Performanec Crate ProCharger 18/21

17. For this test we decided to bolt on our tried-and-true ProCharger D-1SC supercharger. For an engine rated to handle about 8 psi of boost the D-1SC was a bit overkill, but our P-1X test blower was occupied on another test. Still, our goal was to exceed 10 psi of boost, so either would work given the right pulley combination.

019 B8 Chevrolet Performanec Crate ProCharger 19/21

18. For an intercooler we chose our ProCharger heavy-duty air-to-air unit. With large 3.5-inch inlets and outlets it would keep our temperatures in check.

020 B8 Chevrolet Performanec Crate ProCharger 20/21

19. After installation of the ProCharger D-1SC supercharger and intercooler, the power output of the modified LSX376-B8 crate engine jumped from 532 hp and 492 lb-ft of torque to 878 hp and 748 lb-ft of torque. Only the fuel injector sizing limited the power output of this combination, as the power was still climbing.

021 LSX376 B8 Chevrolet Performanec Crate ProCharger 21/21

20. So, in the end we stuffed 13.6 psi into the 8-psi engine and made a ton of sweet intercooled power. In fact, the thing that limited the power output was that our 65-pound FAST fuel injectors were maxed out. Considering that this engine is destined for a certain ’63 Chevy II project we will most like dial it back a bit for the street. But still, it’s nice to know that our Chevrolet Performance LSX376-B8 crate engine is good to go if we decide to dial things up a bit.

Photos by Steven Rupp

Sources

Westech Performance
Mira Loma, CA 91752
951-685-4767
www.westechperformance.com
ProCharger
Lenexa, KS 66215
913-338-2886
www.procharger.com
ATI Performance Products
Baltimore, MD 21207
877-298-4343
www.atiracing.com
FAST
Memphis, TN 38118
877-334-8355
http://www.fuelairspark.com
Chevrolet Performance
chevrolet.com/performance
Competition Cams
800-999-0853
http://www.compcams.com
ARP
Ventura, CA 93003
805-339-2200
arp-bolts.com/
Holley/Hooker
270-781-9741
www.holley.com

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