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Get Race Power From a Street Crate Engine With a Top-End Kit

Elevate Your Crate!

Kevin Tetz Feb 8, 2019
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“Quite simply the most powerful crate engine ever from Chevrolet Performance.” That’s the advertising copy for the LSX 454R that makes 776 hp and nearly 650 lb-ft of torque, according to Chevrolet Performance. That power is amazing, but it comes at a hefty price. Without listing the exact cost, let’s just say it can be more than some project vehicles’ total budget. So needless to say, this engine is not for everyone.

Next on deck is what we’re playing with: the LSX 454 (no “R” designation) with LS7 cylinder heads making a very strong 627 advertised horsepower. Big-block power from a small-block is awesome. The price tag on the non-race version sits between $10K and $12K, depending on the dealer, and still within arm’s reach of the 776hp “R” version when it comes to overall power numbers.

In fairness, there are differences between the two engines internally. The LSX R has a higher compression ratio and runs on race gas only. Our pistons have a D-shaped dish to lower the compression for use with pump gas. So it’s not an apples to apples comparison, especially since the 454R is designated as a race only engine.

However, we wanted to see if we could get closer to the R model power levels, stay on pump gas, and do it with catalog parts and a hot cam. Sure, there are differences in the composition of some of the components, but when we bumped the threshold of 730 hp with a simple head and cam swap, we got some folks’ attention.

Watch how we turned up the wick on an already great engine with a Trick Flow top-end kit and a custom-grind Mast Motorsports camshaft spec’d by John Bouchard. Race power on street dollars and pump gas? We call that having your cake and eating it, too.

The cost of the top-end kit will run you somewhere in the neighborhood of $2,600. We swapped in the kit over lunch on a Saturday and came within 50 hp of the LSX 454R. If you compare dollars to numbers, a Trick Flow top-end kit makes a whole lot of sense on an LSX-equipped street vehicle. For a full-race application, go with the race engine. If you want another 100 horsepower over the crate LSX, consider this top-end combo. We’re not telling you that the two are the same, as there’s no free lunch and you get what you pay for. However, with the way most of us drive on the street, you can get real close to race numbers on pump gas while spending a lot less money. You can spend that extra cash on beefing up the driveline and finding ways to get better traction. You’re gonna need it. CHP

001 LS7 Trick Flow Top End Swap 2/28

We started out with the stock LSX 454 crate engine (with painted block) that’s destined for a super-trick custom Tri-Five pickup. This engine is unaltered, as shipped. These engines don’t come with an intake. The Mast Motorsports two-piece, single-plane intake and Demon 1,050-cfm Dominator carb, as well as the 27-degrees of timing will remain our control factors on this experiment before and after the cam and head swap. The LSX is sitting on the dyno at Tommy’s Auto Machine in Springfield, Tennessee, loaded with stock coil packs, fresh 30-weight break-in oil, E3 spark plugs, and 1 7/8-inch dyno headers.

002 LS7 Trick Flow Top End Swap 3/28

Tommy’s Auto Machine is loaded down with every piece of engine rehab equipment known to the free world. Frank Ofria is the owner/operator and has a history that is deeply rooted in high performance. Coming from California and his father’s legendary Valley Head Service, Frank has operated Tommy’s for almost 20 years in Tennessee, gaining a solid reputation in the local race community, as well as the Nashville street scene.

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The stock (crate engine) cam specs out at 0.635/0.635-inch lift, 236/256-degree duration at 0.050-inch, and a 110-degree lobe separation angle (LSA). Compression is 11:1, but we’re still able to use pump gas. We’ll run several baseline pulls to verify power once the engine is up to operating temps. We expect a little better than the advertised power levels using the giant 1,050 carb and super-efficient Mast two-piece high-rise manifold.

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Frank Ofria checks the humidity levels and records the data into the dyno software to make sure all the readings are accurate. Fuel is metered in and out of the bowls so fuel issues are easily diagnosed.

005 LS7 Trick Flow Top End Swap 6/28

After a couple of half-throttle pulls, Frank does a full pull to 6,500 rpm and nets 677 hp and 547 lb-ft. At this point most people would declare victory and head to the track, but Bouchard is just getting started now that we have a baseline and stock power level to go by. This shows the benefit of the Mast intake right off the bat.

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You can see the torque curve start to drop at 5,300 rpm, but the power curve is smooth and steady all the way up to 6,500. This is what makes this crate package legendary.

007 LS7 Trick Flow Top End Swap 8/28

Here’s a closer look at the Mast intake manifold and the beautiful CNC work on the intake runners. This is not a budget manifold and not what you’d normally run on the street. With the excellent flow potential from the LS heads, the intake can take full advantage of these numbers to make great power.

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Bouchard pulls the ATI balancer off in preparation for the cam swap. We’ll use the same oil and filter with each version to get as close as possible to the same conditions with each set of pulls.

009 LS7 Trick Flow Top End Swap 10/28

Here’s a cool glimpse of the cam card that was in the bag with the new camshaft. Note the “Custom” designation in a handwritten note at the top of the page. Bouchard has had several of his custom grinds given part numbers for the public, maybe this one will as well.

010 LS7 Trick Flow Top End Swap 11/28

The free-breathing LSX (LS7) heads are carefully removed and will get used on another project.

011 LS7 Trick Flow Top End Swap 12/28

After spinning the cam around clockwise several times to seat the lifters into the plastic lifter trays, the stock cam is carefully removed.

012 LS7 Trick Flow Top End Swap 13/28

The new Mast cam specs are 0.650/0.635-inch lift, 245/255-degree duration at 0.050, and a 110-degree LSA. With a healthy 9-degree bump in duration on the intake side, Bouchard feels like it will fully take advantage of the flow capabilities of the Trick Flow heads. Generous quantities of cam assembly lube during installation are used to keep the bearings happy.

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The cam plate is LSX block-specific, so it gets reused. We’re making sure not to damage the O-ring.

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The cam plate is torqued to 18 ft-lb in an even pattern so as not to stress the O-ring.

015 LS7 Trick Flow Top End Swap 16/28

The upper gear is set back to “straight up” with alignment marks in line.

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With the timing cover loosely bolted on, Bouchard shows us a quick trick to align the front seal using the ATI balancer to center the seal over the balancer hub.

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Slowly pressing the balancer onto the crank snout allows you to install to the correct depth while checking the witness marks or wear pattern on the back of the balancer hub.

018 LS7 Trick Flow Top End Swap 19/28

Using a low-torque drill driver, the rest of the bolts get seated on the timing cover in a crosshatch pattern. Gasket technology has improved drastically over the years, and most of the gaskets in this swap were reused.

019 LS7 Trick Flow Top End Swap 20/28

The exception is the head gaskets. Bouchard didn’t want to take chances and installed new Cometic head gaskets and cautions if you’re swapping heads in a hurry to read the fine print on the gasket so you don’t cover any water passages by mixing them up. Unlike the small-block Chevy, LS head gaskets can be installed incorrectly.

020 LS7 Trick Flow Top End Swap 21/28

These are the bad-boy Trick Flow GenX 260 LS7 heads. They came fully assembled, and are a definite upgrade.

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The Trick Flow cylinder heads are loaded with dual valvesprings and titanium retainers and are secured with new factory head bolts.

022 LS7 Trick Flow Top End Swap 23/28

The same E3 spark plugs are reinstalled into the Trick Flow heads.

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The intake manifold gaskets are installed dry, and are the original set.

024 LS7 Trick Flow Top End Swap 25/28

The pushrods and rocker arms are also reused. One of the cool features of the Trick Flow top-end kits is that they’re designed to reuse stock components, utilizing their rocker stand, this does require re-checking pushrod length to ensure proper lifter preload.

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Here’s a closer look at the dual valvesprings and reused stock rocker arms.

026 LS7 Trick Flow Top End Swap 27/28

Our LSX gets run up to temperature again and Bouchard verifies cylinder temps are even across all eight.

027 LS7 Trick Flow Top End Swap 28/28

Frank did a couple of warm-up half-throttle pulls, then ran it up to 7,000 rpm, which netted us 728 hp at 6,400. Torque peaked at 640 lb-ft at 5,500 rpm. The power curve is most impressive, climbing steadily and smoothly past 6,500 rpm. The torque curve peaks at big-block, stump pulling numbers and starts to drop off right around where most guys will shift, making this a deadly street combination.

Photography by Kevin Tetz


Trick Flow Specialties
Tallmadge, OH 44278
Mast Motorsports
Nagodoches, TX 75964
Tommy's Auto Machine & Parts
Springfield, TN 37172
John Bouchard Engines



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