In this episode of Project LS Next, we find out what Mike Mavrigian’s 440 cubic-inch LS engine made on the dyno—after he installed the induction system, ignition, and a pair of valve covers. Don’t cheat and scroll to the end of the story—that’s not cricket.

PT3 26
PT3 28
PT3 29
PT3 34
PT3 35
PT3 37
PT3 38
PT3 40
pt3 44

The Holley intake manifold features CNC machined O-ring grooves at each port. This eliminates the need to use a full-length OE style gasket. The manifold and Trick Flow GenX cylinder heads had near-perfect port alignment and required no port matching.

Port dividers in the intake plenum feature nicely radiused edges for improved flow—no need to “knife edge” them.

Our carburetor is Holley’s 850 cfm Ultra HP double pumper. We installed a 1” phenolic carburetor spacer to enhance upper RPM power production.

Holley offers its cast aluminum LS valve covers in bare natural, polished, or black ceramic coated finishes. I opted for the natural finish so I could have them powdercoated in a dark charcoal wrinkle finish to match the oil pan.

We added a pair of 3/4" thick aluminum spacers to fix clearance issues between the valve covers and the Harland Sharp roller rockers. The spacers seal to the cylinder head via an O-ring strip seat in machined grooves. The spacers seal to the valve covers with OEM style O-ring seals.

Coils can be mounted on the Holley valve covers without using ugly coil brackets. Our MSD coils (MSD- 8287) have the required 72mm bolt spacing to fit properly.

MSD’s 6LS2 ignition controller kit is supplied with plug-in “chips,” each with its own ignition curve. You can also make custom timing curves on your computer using the supplied software.

The completed engine, ready for dyno testing

Scott Gressman at Gressman Powersports (Fremont, OH) making a slight adjustment in carburetor jetting. With #88 jets on the primary and secondary sides, we made the final power pull. The LS Next 440 made 665.2 horsepower at 6,000 RPM. Peak torque was 627.3 ft.-lbs. at 4,900 RPM.

Induction System

We opted to go with a carbureted setup using a Holley single plane intake manifold and an 850 cfm Ultra HP double pumper carburetor. The intake is designed for LS3/L92 applications with an optimum operating range of 2,500 to 7,000 rpm.

During test fitting, we checked the port match between the Trick Flow GenX 255® cylinder heads and the Holley manifold. The port alignment was so good we saw no need to remove any material from either the manifold or head ports. It was as though Holley and Trick Flow consulted with each other when designing these parts.

The manifold has grooves around each intake port for O-ring seals. Holley has an O-ring kit under part number HLY-508-22. A light coat of lithium grease or Vaseline helps keep the seals in place during installation.

The 850 Ultra HP carburetor features lightweight aluminum construction, mechanical secondaries, an electric choke, four-corner idle, clear fuel bowl sight glasses, and optimized street/strip calibration. The carburetor is 100 percent wet-flow tested and ready to run.

Valve Covers

We chose Holley’s new cast aluminum valve covers that feature bosses to mount a set of coils without the need for ugly coil brackets. The appropriate MSD coils are MSD-82878. The earlier LS1/LS6 style coils have shorter spacing and won’t fit.

Our Harland Sharp roller rockers hit the undersides of the stock height valve covers. Rather than going to taller valve covers, we installed a pair of ¾-inch tall ICT billet aluminum spacers to get the necessary clearance. The spacers seal to the cylinder heads with an OEM-style O-ring. The valve covers use a factory type O-ring that seals to the spacers. The valve covers and spacers were secured to the cylinder heads with 3.500-inch long stainless steel socket head cap screws.


Since this build uses a carburetor, the only electronic control system needed is for ignition timing. We used an MSD 6LS-2 controller that connects to the coil harness, water temperature sensor, cam sensor, and crank sensor. The controller features a choice of six pre-programmed ignition curves, or you can create custom ignition curves on your computer using the included software.

Per Trick Flow’s recommendation, we used NGK V-Power spark plugs gapped to 0.045 inch.

Dyno Session

We dynoed the engine at Gressman Powersports in Fremont, OH. Scott Gressman plotted a custom ignition curve using the sofware supplied with the MSD ignition box. Timing at idle was set at 15 degrees, which ramped up to 27 degrees by 2,500 rpm.

The Holley Ultra HP carburetor came with #80 jets in the primary and secondary metering blocks. As we approached peak power levels, the Superflow dyno’s air/fuel monitor indicated a slightly lean condition. Gressman swapped out the jets for #90s, which improved the power and torque numbers but put the A/F ratio on the rich side. We settled on #88 jets for the final power pulls.

The engine made a best of 665.2 horsepower at 6,000 rpm and 627.3 ft.-lbs. of torque at 4,900 rpm. Throttle response was extremely snappy. Given more dyno time, we could have made some incremental power increases by messing with the carburetor and ignition timing. All in all, our LS Next will make a nice stump puller in a mid-size muscle car or an F-body.

Share this Article
Author: Mike Mavrigian

Mike Mavrigian has been building and writing about engines almost as long as there has been internal combustion. He has written well over 1,000 technical articles and seven books, and is editor of Precision Engine Magazine. Mike’s shop, Birchwood Automotive, specializes in street performance and racing engines and vehicle restoration. As you’ll see in this article series, he includes a wealth of information on his engine builds.