LS + Cam + Boost. It’s so easy! (Image/Richard Holdener)

Never before have so many enjoyed so much for so little.

Take a look around. We are smack dab in the middle of the second major Muscle Car era, and this one has taken the power levels to new heights.

I love a DZ302, Boss 429, or Hemi Cuda as much as the next guy, but line one of these muscle motors up against its modern counterpart and you quickly realize how fast things are today.

This modern muscle has plenty of carryover for average enthusiasts, as the LS, Hemis, and Coyotes of the world eventually find their way into wrecking yards.

It’s amazing that you can grab a used LS (as well as a Gen. III Hemi or Coyote), high mileage at that, add a cam, springs and boost, and make four-digit power.

The icing on the cake is that this four-digit power level can also be driven on the street, and get good fuel mileage to boot. Much of the credit goes to the advent of modern fuel injection, but the influx of affordable boost is responsible as well.

To illustrate just how easy we have it these days, and to put one of the Summit S475 turbos [to the test, we decided to take the “easy” route with a 4.8L LR4.

Though our test mule was already fortified with a few mods, this can easily be duplicated with a junkyard version with equal success. That we already had a suitable 4.8L ready to rock, made things that much easier for us.

The 4.8L we’re testing started out as a high-mileage wrecking rat, but some poor choices on our part meant it had to get a fresh set of pistons a few years back. A quick bore (.010) and a new set of forged slugs took care of the damage.

We installed a set of JE forged pistons that featured 7-cc domes to help with our static compression when running naturally aspirated applications.

It also worked under boost, albeit with proper timing, intercooling, and fuel. The forged slugs were swung on a set of well-used, Gen 4 rods, because why not step up from those weak Gen 3 rods?

Never mind that we have made hundreds of pulls on them over 1,000 horsepower, but off they came! The rest of the bottom end included a stock block and crank, along with Fel Pro MLS head gaskets and ARP head studs.

To help this test motor make some power, we upgraded two things — the cam and valve springs.

The stock LR4 cam had long since been swapped out in favor of a Stage 2 turbo cam from Brian Tooley Racing. The cam was combined with a set of 26918 valve springs from COMP Cams. This allowed the 4.8L to not only rev, but actually make decent power.

Remember, the gains offered NA can be multiplied under boost, so a little bump in power becomes much bigger under boost. That’s why we go to the trouble of camming the LS in the first place. The cam and springs were combined with more stock stuff, including the factory 706 heads and truck intake. Sure, there are sexier components to install on the 4.8L (like TFS 205 heads and a Fast LSXR intake), but the stock stuff worked just fine, and it came with the motor when we plucked it from the yard!

Finishing touches included a set of 80-pound ACCEL injectors, Hooker long-tube headers, and a Holley HP management system.

Run in this trim on the dyno, the little 4.8L produced peak numbers of 409 hp at 6,600 rpm and 367 ft.-lbs. of torque. Now it was time for boost!

Boost was supplied by the S475 turbo from Summit Racing.

The twin-scroll, T6 turbo featured a 75-mm compressor (inducer) and an 88-mm turbine (exducer). The turbo also featured a 1.32-A/R ratio turbine housing and the ability to support near 1,000 hp on the right application.

We were not looking to push our test motor there, but it is always nice to know there was a little extra after you get tired of running just 10, 12 or 14 psi (pick your number — you will crank up the boost-they all do!). The turbo was installed with a custom turbo kit which featured a truck manifold, a custom Y-pipe, and a pair of Turbo Smart Gen 5 waste gates.

Turbo Smart also supplied the Race-Port BOV, though they constantly yell at me to upgrade to the latest version. What can I say — I’m OG BOV! Boost from the Summit turbo was supplied through an air-to-water intercooler from ProCharger.

Run first at 7 psi and a soft tune on pump E85 (our low-buck race fuel of choice), the turbo 4.8L produced 576 hp and 525 ft.-lbs. of torque.

Equipped with the BTR stage 2 turbo cam, the naturally aspirated 4.8L produced 409 hp at 6,600 rpm and 367 lb-ft of torque at 6,100 rpm. We love these little 4.8L motors and it was a good starting point for the eventual turbo power. Once we installed the single Summit T6 S475 turbo, the power jumped to 576 hp and 525 lb-ft of torque on E85 (though with a soft timing curve). We eventually cranked it up to 16 psi where the turbo 4.8L produced 829 hp and 761 lb-ft of torque. Ready for those famous last words, there was a lot left!       
The graph illustrates the power gains offered at each boost level provided by the T6 S475 turbo from Summit Racing. We started near 7 psi then ran up as high as 16 psi. Note how each successive jump in boost resulted in a jump not just in peak power, but in power and torque through the entire rev range. Having extra peak power is always nice, but having extra power everywhere is what makes cranking up the boost so addictive. It is important note the S475 still had nearly 200 hp in reserve, especially on this small motor, where backpressure would be less of a concern. Higher boost might push this little 4.8L right past the 1,000-hp mark.   

After stepping up to a solid 16 psi, the power needle showed 829 hp and 761 ft.-lbs. of torque. Take a look at the power curves in the supplied graphs and you can see the power outputs at different boost levels. You can also see that the turbo was ready to support even more power, but how can you complain about an 800-hp 4.8L?

Especially when it was so easy.

Though the power numbers can easily be duplicated by a junkyard 4.8L, our test motor was previously upgraded with a set of JE forged pistons. Also present were a set of Gen-4 rods, MLS gaskets and ARP head studs. (Image/Richard Holdener)
Replacing the stock LR4 cam is a must when looking for power. This test motor was sporting a stage-2 turbo cam from BTR. (Image/Richard Holdener)
Nothing fancy here, just a set of stock 706 cylinder heads. These stock heads were more than enough for the little 4.8L, especially under boost. (Image/Richard Holdener)
The 706 heads did receive a valve spring upgrade. To work with the BTR cam, we installed a set of 26918 springs from COMP Cams. (Image/Richard Holdener)
Perched on top of the 706 heads was an early truck intake. Again, these truck intakes make good power, especially with boost. (Image/Richard Holdener)
The one thing we did upgrade was the factory truck injectors. They were replaced with a set of ACCEL 80-pounders to ensure adequate fuel flow to support the turbo power. (Image/Richard Holdener)
On the NA runs, we relied on a set of Hooker long-tube headers feeding 3.0-inch collector extensions and Magnaflow mufflers. (Image/Richard Holdener)
To dial in the air/fuel and timing curves on the 4.8L, we relied on a Holley HP management system. (Image/Richard Holdener)
Run first in naturally aspirated trim, the mild 4.8L produced 409 hp at 6,600 rpm and 367 ft.-lbs. at 5,100 rpm. (Image/Richard Holdener)
Now it was time for some boost from the Summit S475 turbo. (Image/Richard Holdener)
The turbo system featured factory truck manifolds reversed to face forward. (Image/Richard Holdener)
The Y pipe featured a pair of Gen-5, Turbo-Smart waste gates to control the boost pressure supplied by the Summit turbo. (Image/Richard Holdener)
Capable of supporting over 1,000 hp, this S475, T6 turbo from Summit Racing offered more than enough power for our little 4.8L. (Image/Richard Holdener)
Boost was supplied from the Summit T6 turbo to a ProCharger air-to-water intercooler. (Image/Richard Holdener)
The T6 turbo was run with a reducer that allowed installation of a 4.0-inch exhaust. (Image/Richard Holdener)
Run on the dyno with the Summit turbo, the boosted 4.8L produced 576 hp near 7 psi with a soft tune, but we eventually ramped this up to 828 hp and 762 ft.-lbs. of torque at 16 psi. There was obviously plenty left in the 1,000-hp Summit turbo, but we stopped here because we have a lot more testing in store for the little 4.8L, including compound turbos. Check out my YouTube channel for full results of the compound turbo testing. (Image/Richard Holdener)

Richard Holdener is a technical editor with over 25 years of hands-on experience in the automotive industry. He's authored several books on performance engine building and written numerous articles for publications like Hot Rod, Car Craft, Super Chevy, Power & Performance, GM High Tech, and many others.