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When we launched our Pro-Luxury Cadillac project, we quickly decided on LS power for the build. Like most Caddies, this car is packing a lot of pounds on its enormous frame. It needs plenty of oomph to put all that mass in motion, so we conjured up a plan for a budget-friendly turbocharged engine that’s up to the task.
Building a midrange boosted LS engine typically starts with a 5.3-liter Vortec such as an LM7. These are readily available everywhere for less than $1000. We got ours off Marketplace in pieces for $500. The engine had about 150k miles on it. The cylinder bores looked okay, with no gouges or scuffs, but the whole motor was incredibly dirty.
It was clear that whoever owned this engine rarely changed the oil. The plan all along was a budget(ish) turbo build. But we did opt to spend a little more for a complete bottom-end rebuild kit (Summit Racing CMB-08-0068 $478), and a big ol’ Stage 2 turbo cam. After checking the crank and rods, we determined we could safely run standard bearings for the bottom end, along with new rings and standard flat-top pistons. The bottom end went together quickly without any issues. Now it’s time for the good stuff – the top-end assembly.
We freshened up the stock 862 head castings with new dual valve springs from a Summit/Trick Flow cam kit (PN #SUM-8706-1DT $579), along with new valve seals, keepers, locks, and locators. The new springs are good for .650” lift, which will work great with our Summit Racing Stage 2 Turbo cam with 275/283 duration (advertised), .600”/.575” lift, and 114-degree LSA. Because we pulled the valves out, we spent some time cleaning the valve stems and lapping the valves to each seat with some fine compound before pressure washing the heads and reassembling everything.
To install the Holley 302-2 oil pan, we had to cut a few inches off the full-length windage tray and notch it to clear the new pickup tube.
To finish up the bottom of the engine, we installed a new Holley 302-2 oil pan. This pan requires modifying the factory windage tray, which we did on our bandsaw. This gave us the necessary clearance for the new pickup tube. The new pan doesn’t come with a gasket, so we used the one that comes in the Mr. Gasket master overhaul kit. We also used Mr. Gasket stainless steel oil pan bolts (PN #60850G $36) instead of the crusty originals.
This build is all Holley on the top end. We used a Mr. Gasket LS gasket kit (PN #61001G $470) for all the necessary gaskets. This kit comes with premium MLS gaskets for the best cylinder seal, which is a good idea for a boosted LS. To hold the heads down, we opted for a set of Earl’s head bolts (PN # HBS-001ERL $180) instead of studs. We did spend a little more money on a few items just for looks, such as Mr. Gasket stainless steel bolt sets for all the engine covers and mounts. The cylinder heads were topped off with a set of Holley valve covers (PN #241-112 $282), and a smooth valley cover (PB #241-262 $170).
The Mr. Gasket premium gasket kit came with MLS head gaskets, which work well with boosted LS engines like this one. The stock head bolts had to go, so we opted for some reusable bolts from Earl’s. The threads, washer, and head of the bolt were lathered up with some moly lube to ensure they don’t give false torque readings.
While we could have stuck with the stock truck intake for bottom-end grunt, we are boosting this LM7, so we splurged on a Holley Ultra Lo-Ram intake manifold (300-621 $885) to give maximum hood clearance and complete the look we’re after. With this manifold, the fuel rails are actually taller than the intake plenum, which is wild.
The short intake provides ample clearance up top, giving us the option to raise the engine a bit if we encounter chassis interference. Installing the modular intake requires cutting and glueing some O-rings to seal the pieces. We bolted a Holley Sniper 102mm throttle body (PN #860002-1 $240) to the front of the intake to complete the induction package. We also installed an Earl’s LS steam line kit (26-550 $144) to clean up the steam lines. This kit uses only the front two ports; the OE block-offs were retained on the back of the heads.
We could have left the original steam-line blocks, but we love the look of these Earl’s adjustable ports. We kept the rear ports as they left the factory but used the Earl’s ones up front. We covered the valley with a Holley trussed cover and Mr. Gasket SS bolts.
Wrapping up the 5.3 LM7 build is a set of MSD Coils (PN #826583 $589), E3 spark plugs, and Accel Ceramic plug wires (PN #9004C $165). We plan to bolt Hooker Turbo LS manifolds and a single turbo onto the engine once we get it dropped into the Caddy. With the 862 heads, our LM7 should be right at 9.9:1 compression and 8 psi of boost to make about 500hp, which is well within reason with this combo.
All in, we’re at $5706 for this build, including the original engine and short-block parts. Using Holley components, we’ve turned this otherwise mundane 5.3L into a killer powerplant for our Pro-Luxury Cadillac project.
The intake uses individual O-ring seals, which we installed into the base with silicone paste lube. The other sections of the intake require cutting sealing rope. The upper plenum cover uses a similar sealing rope, but it gets cut flush at the ends of the intake opening.
We lubed the new Holley 36lb/hr. injectors, dropped them into the intake and installed the supplied fuel rails. These injectors use the tall fuel rail mounts (the intake comes with short and tall mounts.)
We topped the engine off with a set of Holley valve covers and Mr. Gasket O-rings, along with MSD coils and Accel ceramic plug wires.
