Mark Stielow’s Camaros have always been on the leading edge of the latest high-tech horsepower movements, and his latest project, Gunner, is no exception. He’s jumped headlong into the emerging LT swap trend, using a Scoggin-Dickey Parts Center-supplied Chevrolet Performance LT4 crate engine.
It’s the engine, of course, that powers the current-generation Corvette Z06 and Camaro ZL1. With a little more than 9 psi of boost generated from an Eaton 1.7L R1740 TVS supercharger spinning at up to 20,000 rpm, the LT4 cranks out an impressive 650 horsepower and 650 lb-ft of torque.
“I’ve always liked the immediate power delivery that comes with supercharging, and the LT4 is a great engine in that regard, with a broad powerband and tremendous low-end punch,” says Stielow. “Considering the technology and performance wrapped up in the crate engine, it would be virtually impossible to build something comparable from the ground up, making it a cost-effective and time-saving choice.”
Despite many architectural similarities with the previous-generation Gen III/IV LS engines, the Gen V LT family has a number of significant changes that make engine swaps just that much more challenging—at least in these early adopter days. For one thing, the engine mounts and even the engine mounting positions on the cylinder block are not shared with LS engines, while the engine accessory drive systems are different, too. In fact, there are no factory applications with conventional hydraulic power steering (the Z06 and ZL1 have electric power steering), meaning a system has to be fabricated.
Finally, and perhaps most importantly, the Gen V LT engines are direct injected, with extremely high fuel pressure. Where the LS engines’ conventional port-injection system operates at up to around 60 psi, the LT engines’ fuel pressure is more than 2,000 psi. In the case of the supercharged LT4, it’s around 2,900 psi.
A camshaft-driven fuel pump mounted to the engine generates the high pressure at the fuel rail and it’s all self-contained within the crate engine package from Chevrolet, but the kicker here is the LT4 needs a very specific engine controller and an additional pulse-width modulated fuel pump controller.
Stielow is stepping around the factory system, somewhat, to set up a steady fuel pressure feed to the engine’s high-pressure pump. He’s doing it with a VaporWorx setup to build extra headroom into the system as part of a plan to up the engine’s output later. We’ll address the engine’s fuel and control systems more thoroughly in a later installment.
When it came to installing the crate engine, Sled Alley in Clinton Township, Michigan—the shop handling the bulk of the Camaro’s fabrication—and Holley collaborated on a set of engine mounts for the car’s Detroit Speed front subframe. We touched on that in a previous installment, but the final, production-spec mounts were used for this stage of the installation. Holley also sent representatives from their Hooker Headers division to fab long-tube and mid-length headers, which will be used as the pattern for production-swap headers. We’ll highlight an entire story on the exhaust system’s fabrication later.
“The mounts are different, which definitely affects a couple of things, but if you’re used to doing LS swaps, the LT swap is in the same ballpark,” said Sled Alley’s Matt Gurjack. “But there are still supporting parts that aren’t in the aftermarket yet. We were fortunate to work with Holley on this project, and builders after this will benefit from the collaboration with new production swap parts, but it’s something to keep in mind when tackling an LT swap right now. It’s going to require some fabrication.”
Backing the LT4 in Gunner is the proven TREMEC Magnum six-speed manual transmission, which was prepared by D&D Performance and adapted to the engine with a Quick Time bellhousing (another Holley brand). The Camaro’s transmission tunnel required some modifications for the desired fitment, which we covered in a previous installment.
Finally, after the engine and trans were installed, Stielow got to work on the wiring harness. There will be more on that in a future installment as well, but for now we’re focused on the installation details of this leading-edge LT swap.
It’s also important to note that, as Matt Gurjack noted, the LT swap trend is still in its infancy and supporting components are coming to the market almost daily. It’s a good bet new mounts and other parts have entered the market in the time it took us to shoot, write, and publish this story.
It’s definitely the next wave in engine swaps and, as always, Mark Stielow is leading the way.
1. Obtained from Scoggin-Dickey Parts Center, the dry-sump Chevrolet Performance LT4 crate engine (PN 19332702) carries a $13,755 list price on S-D’s website. For roughly $500 less, there’s also a wet-sump version (PN 19332621). Considering its lofty 650-hp/650-lb-ft output, it’s difficult to argue with the price because you’d be hard-pressed to assemble a blower-ready long-block and add the supercharger, fuel system, etc., for any less. The accessory drive system shown in this image, however, is not included and neither is the engine controller.
2. A TREMEC Magnum six-speed is a good match with the LT4, with a torque rating of 700 lb-ft. Within the aluminum case, the guts are based on the later-model TR-6060, with thicker, heavier-duty, and stronger gears than the T-56 transmission. It weighs about 135 pounds, which ain’t bad for a gearbox with so much capacity.
3. Prior to installation, the Magnum transmission was taken to D&D Performance for a couple of upgrades, which included pulling off the original plastic shift fork pads and replacing them with more durable bronze pads. If the plastic pads break or wear, the sliders won’t fully engage their respective gears.
4. Stielow wanted to lower the top-gear cruising rpm so the transmission’s original 0.63:1 Sixth-gear cog was swapped with a 0.50 gear, which should lower engine speed by around 400 rpm at 70 mph, giving the supercharged muscle car better fuel economy. By the way, the Magnum is offered in two versions: one with a 2.66 First gear and one with a 2.97 First gear. Stielow is using the 2.66 version. (TREMEC has a cool app to allow you to evaluate your gear ratio choices.)
5. The LT4 uses an eight-bolt pattern for the flywheel, like the LSA production engine and LSX454 crate engine. The crate engine doesn’t include the flywheel and Chevrolet Performance offers one through their catalog, but Stielow went with a Centerforce flywheel to support the added power that will come later.
6. Next, a new DYAD Centerforce dual-friction clutch was installed. Stielow used the same model in three previous Camaro projects that made over 950 lb-ft of torque, and he says it offers exceptional holding power with great driveability, including a great pedal feel and easy modulation.
7. When it came to marrying the Magnum transmission to the LT4, a Quick Time bellhousing served as the intermediary. The bolt pattern is largely the same as the LS engine family. The top bolt position is different but it still enables the Quick Time LS bellhousing to be used. It’s a steel unit that’s SFI 6.1-certified.
8. Sled Alley modified the Centerforce hydraulic release bearing assembly to use this hard line to the clutch master cylinder. The AN fittings enable a “dry break,” allowing the transmission to be removed much easier for service.
9. New Holley engine mounts lock the LT4 in place on the Detroit Speed subframe. They’re new and designed specifically for LT swaps using the Detroit Speed front end, but the word is mounts for original first-gen F-body subframes, as well as A-body and truck applications, are on their way.
10. Nothing makes an engine installation easier than having the front-end sheetmetal and core support out of the way; and here, the Sled Alley guys slowly begin to slip the engine/transmission assembly into the car, taking care to avoid scratching the freshly powdercoated chassis components.
11. The top portions of the engine mounts bolt to the engine. A little antiseize compound on the threads is used as a precaution because the steel bolts are threading into the aluminum block.
12. It takes a little finesse to line up the top of the mounts over the bottom sections, but once they are, through-bolts simply hold the two together to complete the installation.
13. The transmission crossmember is the result of another collaboration among Stielow, Sled Alley, and Holley. Sled Alley started with Holley’s LS-swap crossmember and found there were just enough small differences with the positioning of the LT engine that modifications were required. They made them and now Holley’s new LT swap crossmember is based on this first one in Stielow’s car. You’re welcome.
14. A Walbro pump is mounted with the transmission on a fabricated bracket to support the transmission cooler. The lines will feed in and out of a heat exchanger built into a C&R radiator.
15. One of the enhancements made to the engine was the replacement of the factory intercooler lid with the one used on the Camaro ZL1. The 2017 Corvette Z06 received a similar lid, but it says “CORVETTE” on top rather than “SUPERCHARGED.” The upshot with the revised designed is a more efficient inlet/outlet design, along with revised “bricks” within the intercooler, all of which is intended to improve cooling by reducing the chance for power-robbing heat soak. Stielow ordered the lid from a Chevrolet dealer, but at the time our story was completed the complementing heat-exchanger bricks were not available. That may change soon and when we learn more we’ll pass along the information.
16. Here’s a shot of the factory, pre-2017 Z06 intercooler lid. It’s easy to see how it tapers down at the front, compared to the new lid—a design feature that didn’t enable optimal cooling efficiency. It’s important to reiterate the advantage of the updated lid is in the application of revised heat-exchanger bricks. The lid is simply required to clear the bricks and will not itself help without them.
17. The LT4 crate engine doesn’t include an accessory drive system and there are two choices from Chevrolet Performance: a CTS-V-based kit for wet-sump applications and a Corvette-based system for dry-sump engines. The dry-sump version (PN 19332614) was used on this project, but it included an A/C compressor that simply didn’t fit. Changes were required. The ABS module and lines had been fitted, too, when this photo was taken.
18. The factory A/C compressor included with the Chevrolet Performance accessory drive was too large and its ports clocked all wrong for the engine’s installation in the Detroit Speed subframe. It will be an issue for stock early F-body frames as well. The solution involved replacing it with a more compact, swap-friendly Sanden unit from Vintage Air. Even still, the subframe required a clearance notch and a mounting bracket was fabricated. Holley stepped up with assistance for the bracket and it may become part of their catalog of LT swap components. This image is from the test-fit/fabrication stage of the installation, prior to the chassis’ powdercoating.
19. Adding hydraulically based power steering was a challenge, and as we outlined in a previous installment, it was solved with a power steering pump and pulley from Turn One. Turn One offers a pump to take the extra load of being in the blower belt track. A power steering pump mount and relocated tensioner were required to fit the DSE chassis; and with some careful layout and component placement adjustments, the stock LT4 blower belt was retained. Because of the packaging requirements, a remote fluid reservoir was required.
20. Additional parts are added to start filling in the blanks of the installation, including the pump for the intercooling system. This is the one called out in the instructions for the crate engine and plugs right into the LT4 wiring harness.
21. Exhaust headers are another important part of the LT swap and Hooker Headers used Stielow’s Camaro to design and fabricate long-tube and mid-length versions that will go into production shortly. We’ll have more on this in an upcoming installment. Stielow’s car will ultimately receive a set of stainless headers with 1 7/8-inch primaries feeding a 4-into-1 collector.
22. The Chevrolet Performance controller for the LT4 is offered in two versions: one for use with the Magnum transmission or a conventional four-speed automatic (PN 19331517) and one for use with GM’s eight-speed automatic (PN 19355174). Along with the controller itself, the kits include the mass air sensor, oxygen sensors, and the all-important fuel pump power module. Here, Mark Stielow lays out some of the harnesses prior to connecting them to the engine. There’s a lot to this portion of the LT swap and we’ll have more on it in a later installment.
Photos: Barry Kluczyk