Best LS Engine Marine Conversion Kit for Boat Projects
When swapping an LS engine into a boat, choose a kit that simplifies installation, aligns crank centerline, and minimizes fitment issues. This guide highlights five adaptable LS conversion kits designed for marine or multi-application swaps, focusing on engine mounts, brackets, and supporting components. Ideal buyers include rebuilders, do-it-yourself boat enthusiasts, and small shop installers seeking reliable alignment and durable construction. The selections prioritize universal fit, aluminum or steel construction, and clear installation paths. Use the buying guide below to compare fitment, material quality, and installation considerations before purchasing.
| Product | Best For | Material | Notes |
|---|---|---|---|
| ECOTRIC LS Conversion Engine Mount Kit | Boat projects with 88-99 GM C/K series swaps | Steel | Adjustable, multi-position; potential interference with frame crossmembers |
| Michigan Motorsports AFM/DOD Conversion Kit | Conversions needing AFM/DOD removal for reliability | Various components included | Full kit with gaskets and lifters for cathedral-port engines |
| for LS Swap Motor Mounts Adapter Plates – Universal Kit | Universal small-block to LS engine swaps | Billet aluminum | Crankline offset +.17″ in vehicle |
| Bevinsee LS Engine Serpentine Bracket | Accessory drive conversion for LS swaps | CNC-machined components | Note on installation methods and belt length variability |
| for LS Swap Motor Mounts Adapter Plates – Mejiiao Kit | Engine mounting with OEM-fitment optimization | Aluminum | Crankline offset +.17″ |
ECOTRIC LS Conversion Engine Mount Kit
Best for classic GM trucks and boats needing a straightforward LS installation into older frames. The kit is designed for LS1, LS2, LS3, LS6, LSX, LQ4, LQ9, 4.8, 5.3, 6.0, and 6.2 engines. It offers adjustable mounting positions and laser-cut steel construction. It is suitable for swaps where the engine needs some forward or rearward adjustment and where a low-profile mount is essential. A potential limitation is frame crossmember interference or A/C positioning, which can require additional trimming or modifications.
- Best for: Boats or vehicles with older chassis seeking a robust, multi-position LS mount.
- Better for: Systems needing adjustable engine placement and durable steel mounting.
- Limitations: May require frame clearance checks and compatibility verification with the boat’s existing drivetrain layout.
Bevinsee LS Engine Serpentine Bracket
Best for adding or restoring the serpentine and power steering drive on LS swaps in marine or automotive applications. The bracket set is CNC-machined for a precise fit and includes instructions. Installation options are described in the product materials, but exact belt lengths may vary by winding method and bracket composition. It works with LS1, LS2, LS3, LS6, LS7 engines, including 4.8L, 5.3L, 6.0L, and 6.2L variants. A caution is that belt length compatibility can differ by vehicle and configuration, so verify your pulleys and routing before purchase.
- Best for: Replacing or upgrading the serpentine and power steering bracketry in LS swaps.
- Better for: Projects needing a precise CNC-machined part with clear installation guidance.
- Limitations: Belt length compatibility can vary; digital reference may be needed for exact fit.
Yoursme LS Engine Mounts Adapter Plates
Best for universal small-block to LS engine swaps with a billet aluminum build. These adapter plates move the crankshaft centerline up by approximately 0.17 inches, aiding engine alignment in crowded engine bays typical of marine installations. The kit includes two adapter plates and the necessary bolts. It’s well-suited for boat projects needing a stronger, precisely machined mounting solution. A limitation is that the plates are M10-threaded and require the included hardware; verify compatibility with your block and mounting studs before purchasing.
- Best for: Universal small-block to LS engine mounting in tight marine spaces.
- Better for: Users seeking CNC-milled aluminum accuracy and a straightforward install.
- Limitations: Requires checking thread compatibility and hardware integration with your engine block.
ZhuanYi Mr LS Engine Main Bolt and Stud Kit
Best for replacing LS main bolts and studs during an engine swap or rebuild in marine-sized bays. The kit includes Grade 10.9 hardware engineered for high-torque environments across LS1, LS2, LS3, LQ4, LM7, LC9, LR4, L96, and L76 variants from 1997 to 2013. It provides a direct hardware replacement solution that helps restore mounting integrity and reliability in demanding applications. A caution is to confirm the kit covers the exact fastener lengths needed for your specific engine model and installation.
- Best for: Replacing engine fasteners during LS swaps or builds.
- Better for: High-strength Grade 10.9 bolts and a broad LS compatibility range.
- Limitations: Verify exact fastener lengths and thread pitches for your engine block and mounts.
Buying Guide
Key considerations for selecting an LS engine marine conversion kit include fitment, material strength, and installation practicality. For boats, alignment and space are critical. Prioritize kits that offer adjustable mounting positions, clear installation instructions, and compatibility with common LS variants. Aluminum adapter plates save weight but may require additional reinforcement in saltwater environments; steel mounts tend to be more durable but heavier. Confirm whether the kit includes all required mounting bolts and gaskets, and check for any needed auxiliary components such as pulleys, brackets, or serpentine belts.
- What height and offset do you need? Some kits move the crank centerline by about 0.17 inches to improve fit in tight engine bays.
- Is the kit compatible with cathedral-port or truck LS engines you plan to use?
- Do you need AFM/DOD removal components or harnesses included in a kit?
- Will your boat’s frame and crossmembers require additional trimming or reinforcement?
- Is there a requirement for CNC precision or billet aluminum on the mounting plates?
Quick comparison
- ECOTRIC LS Mount Kit — best for flexible engine placement, steel construction, broader compatibility with LS variants.
- Michigan Motorsports AFM/DOD Conversion Kit — best for removing AFM components and improving long-term reliability.
- Yoursme LS Adapter Plates — best for universal small-block to LS swaps with precise alignment.
- Bevinsee Serpentine Bracket — best for accessory drive compatibility in LS swaps.
- Mejiao LS Adapter — best for OEM-fitment alignment and CNC-milled aluminum durability.
FAQ
What is the main benefit of using an LS engine conversion kit in a boat?
Such kits align the LS engine properly in the engine bay, help with mounting stability, and simplify installation by providing compatible brackets and plates.
Do these kits affect engine bay clearance?
Yes. Some kits move the crank centerline or reposition brackets, which can affect clearance around fuel lines, hoses, and the hull structure.
Are aftermarket LS mounting components marine-rated?
Not all are marine-rated; check for corrosion resistance and suitability for saltwater use, especially for brackets and bolts.
Do I need additional parts to complete the swap?
Possibly. Depending on your engine, you might need pulleys, belts, or gaskets not all kits include. Verify contents before buying.
Is professional installation recommended?
For marine applications, professional installation is often advised to ensure proper alignment, load distribution, and water exposure considerations.