Ask ten LS builders how to make a block live under serious boost and you'll hear the same short list: sleeve it, buy an aftermarket block, or send it out for machine work. All three work. All three also cost real money and real time, and they take the block out of your hands for weeks. If your plan is a boosted junkyard LQ or a hard-hitting LS street car, there's another option you can do in your own garage: an LS block filler that supports the cylinders without machining.
Why LS builders look at block filler
The LS family is one of the most popular platforms for forced induction, and a lot of those builds start with a stock block. Around each cylinder sits the water jacket. That's what keeps a stock engine cool, but it also means the upper cylinder walls have room to move once you add boost, more cylinder pressure and more heat. When the bores move, the head gasket has a harder time sealing, and that's where many high-horsepower headaches begin.
Block filler is an old idea in the V8 world. Racers have filled water jackets for years to stiffen the cylinders on drag engines. EPOXY54 takes that idea and offers two ways to use it: a partial fill that keeps your stock cooling, or a full fill for dedicated race engines.
Aluminum LS or iron LQ? EPOXY54 covers both
LS-family blocks come in both aluminum and cast iron, so the first question most people ask is whether a product called "The Aluminum Block Epoxy Kit" will work on their block.
- Aluminum LS blocks. GM's aluminum LS blocks (LS1, LS2, LS3 and similar) are on our list of open-deck applications, alongside BMW N54, Honda K-series, Subaru EJ and FA, and Mitsubishi 4B11. EPOXY54 is designed to adhere permanently to aluminum, with a thermal expansion rate closely matching aluminum.
- Iron LQ and LSX blocks. The iron truck blocks (LQ4, LQ9 and similar) and LSX race blocks are cast iron. EPOXY54 was engineered for aluminum, but many customers use it successfully in cast iron applications, and LS variants are on that list along with small block Chevys and 2JZ-GTEs. We cover this in detail in Cast Iron Engine Block Filler (Hard Blok & Moroso Predecessor).
Whichever block you have, surface prep matters: clean and degrease the water jacket thoroughly before you pour.
What EPOXY54 brings to an LS block
EPOXY54 is a two-part, high-temperature epoxy that converts open-deck engine blocks to closed-deck strength without machining. Here's what matters once it's in the jacket:
- 21,000 psi compressive strength once cured, to support the tops of the cylinders.
- Non-expanding and non-shrinking, so it doesn't push on the bores or pull away from the jacket walls as it cures.
- Runny consistency that flows into the jacket for a clean application.
- Cures in 24 hours. No machine shop queue.
Comparing it with other reinforcement methods? See EPOXY54 vs. Traditional Block Guards.
Partial Fill or Dry Block for an LS?
Partial Fill (OEM coolant capabilities) puts epoxy only in the top ¾" of the water jacket, where the cylinders move most. Coolant still flows underneath, so the engine keeps its stock cooling. This is the choice for boosted street cars, trucks and anything that sees regular driving. Wondering how that works? Read How Does the Engine Cool After EPOXY54?
Dry Block (no coolant: track use only) fills the jacket completely and is meant for dedicated drag and track engines. The V8 Dry Block kit is two 1080 ml kits, one per bank. Jacket volume varies from block to block, so measure yours first with our guide to measuring for a Dry Block / Full Fill.
Still deciding? Partial Fill vs. Dry Block walks through the trade-offs, and Why Are EPOXY54 Kits Different Prices? explains why a V8 kit costs more than an inline 4.
The install: five steps, no machining
- Fill the lower water jacket with a temporary solute such as sugar or salt.
- Mix Part A and Part B, then pour the epoxy into the top ¾" of the jacket, on top of the solute.
- Let it cure for 24 hours.
- Drill the coolant passages to match your head gasket design.
- Dissolve the solute with water and flush it out, leaving the epoxy layer behind.
Complete instructions and an installation video come with every kit. The EPOXY54 Install Kit puts the accessories for the job in one box; here's what it is and what it isn't. Planning the rest of the build? Our Ultimate Engine Build List is a good checklist while the block is apart.
Reinforce your LS block without the machine shop
If your LS plan says "more boost" and your budget says "no new block," EPOXY54 gives you a block filler you can install yourself. Choose V8 and your cooling configuration on the EPOXY54 product page and you'll have what you need to reinforce the cylinders. Made in USA.