LS Engine Parts and Accessories

How-To-LS Swap a Marine application

Like many people, you have already come to recognize the dominance of the LS engine platform from all types of motorsports and powersports.

So imagine you were doing the same engine swap into a car, sand rail, air boat or virtually anything for that matter. What's more important than knowing what the engine needs is knowing what the boat needs from the engine to make it a compatible fit.

The first thing to ask yourself or the installer what does the car, boat or anything need or require to accept a new LS Based engine or retrofit. A marine application is no different what the engine needs is based entirely on what the engine is mating to. Below are a list of the most common questions to ponder before you start your project.

  1. What is the exact application and or drive type you're adapting to? Jet? Bravo? Alpha? #6 Sterndrive? V-Drive? Wakeboard boat configuration?
  2. What does the current engine have on it for accessories that the new engine will need? Will you want just a sea water cooling pump and will you fabricate your own accessories mounting and or drive ? Or do you want a complete kit?
  3. Is the engine Aluminum or Iron block? Are you going to want closed cooling?
  4. What style of motor mounts does your current engine use that you will have to adapt to?
  5. If you're adapting to a sterndrive application and you have an Alpha Outdrive you will need a modern Bravo bellhousing and LS Flywheel and coupler.
  6. Does your LS engine have a long or short crankshaft snout? This is critical in indentifying starters, flywheels, PTO, etc.
  7. Where does your current exhaust exit and can the new LS exhaust adapt to your current exit location? Will you want aluminum exhaust or Stainless steel headers?
  8. Does your engine use a carburetor or EFI? If EFI how many O2 sensors will you be using? one or two?

We have tried to address all of these but due to so many variables there is no such thing as a kit. There is no way to make one size shoe fit everyone basically. But we are here to support you through the journey. We've also partnered with Powerboat 1 to develop a technical advice video series on converting an LS Engine for use in a jet application. Check out the video series here!

Happy Boating!
LS1 Small Block Chevy Exhaust System
Your Price:
$29.99

Exhaust Gaskets for LS Marine Aluminum Exhaust Manifold System

620-32496

Exhaust Gaskets for LS Marine Aluminum Exhaust Manifold System

Replacement Exhaust Gaskets for the 620-32940 or 620-32942 LS Exhaust Systems or IMCO LS Exhaust Systems. Sold in pairs for one engine.


LS1 Small Block Chevy Exhaust System
Your Price:
$1,375.99

Stainless Risers for LS Marine Aluminum Exhaust Manifold System

620-32938

Stainless Steel Risers for LS Marine Aluminum Exhaust Manifold System

Change out the cast aluminum risers on the 620-32940 or 620-32942 LS Exhaust Systems for Stainless Steel ones! Sold in pairs.


CMI LS Chevy E-Top Headers
Starting From:
$4,399.99

This Part has options, please click the button below to order.

CMI LS Chevy E-Top Headers

650-1320 + Option(s)

CMI CMI LS Chevy E-Top Headers, Polished or Satin Finish

  • Improved exhaust flow over existing cast manifolds
  • Lightweight 316L stainless steel
  • Increased fuel efficiency
  • Inside port size of 1-5/8", also in 1-7 /8"
  • Smooth mandrel bent tubes
  • No separate tailpipe required
  • Taller custom application options

Note: All CMI Systems are sold without Tailpipes

ALL CMI HEADERS ARE MADE TO ORDER AND SHIP FROM THE FACTORY IN 2-3 WEEKS

GM Gen III/IV Small Block V8. LS Series .030" MLS Exhaust Gaskets.
Your Price:
$32.99

GM Gen III/IV Small Block V8. LS Series .030" MLS Exhaust Gaskets.

302-C5818-030

GM Gen III/IV Small Block V8. LS Series .030" MLS Exhaust Gaskets. - Sold in Pairs

The Cometic Severe Duty Multi Layer Series exhaust gaskets are comprised of three separate layers of stainless steel. Cometic uses stainless steel for increased strength and its ability to rebound from heat compression, plus excellent corrosion resistance. The outer layers of the gasket are embossed and coated. This is designed to meet the demands of a variety of harsh sealing environments, load conditions and surface finishes.

The Severe Duty MLS exhaust gasket is ideal for both aluminum heads & cast iron heads as well as cast iron and aluminum blocks. The composition of MLS gaskets will also withstand the shearing forces created by aluminum heads on cast iron blocks. No re-torque is required and by design promotes an even torque load across the sealing surface.

Sold in Pairs


LS Exhaust Gasket
Your Price:
$37.99

LS Exhaust Gasket

650-34015

LS Exhaust Gasket

Sold Each


Small Block Chevy "Low" Valve Covers
Your Price:
$522.95

Holley LS Chevy Valve Covers - Black

710-241-182

Holley LS Chevy Valve Covers - Black

Holley's new 2-Piece LS valve covers are a great way to update the look of your LS engine without the use of complicated adapter systems or the hassle of remote coil relocation. These modular LS valve covers feature an OE height, internally baffled LS valve cover base with integrated coil mounts for popular Gen I and Gen V style LS coil bodies, and a vintage style finned overcover that hides the unsightly LS coils and messy wiring harness - allowing the full performance benefits of coil-on-cover ignition setups without the robotic styling. Each modular coil cover features a simplified version of our Vintage Series style fins that seamlessly blends with other finned Holley dress-up accessories such as our LS valley covers and 14" round air cleaners. The coil cover also features cast-in provisions for the spark plug boots and coil wiring harness so no extensions or custom wiring is required.

Each 2-Piece LS valve cover set includes a low-profile billet oil fill cap, hardware and spacers for mounting both versions of LS coil bodies, and 12-point dress up hardware and rubber grommets for the coil covers. These modular LS valve covers are now offered in 5 unique finishes: natural cast, polished, satin black, factory orange, and gloss red (black, factory orange and gloss red sets feature machined fins).

  • Cast aluminum 2-Piece LS valve covers designed to mount and hide both Gen I and Gen V style LS coil bodies
  • Retain the performance of factory coil-on-cover ignition without the unsightly styling
  • Base fits LS1, LS2, LS3, LS6 and LS7 engines with clearance for .750” lift cam with stock style rocker arms
  • Base features internally baffled ventilation system
  • Coil cover features Holley vintage style fins and cast-in wiring provisions
  • No coil relocation, wire harness extensions, or custom spark plug wires required
  • Includes low-profile billet oil fill cap
  • Includes all necessary coil mounting and dress-up hardware

 


Small Block Chevy "Low" Valve Covers
Your Price:
$614.95

Holley LS Chevy Valve Covers - Polished

710-241-181

Holley LS Chevy Valve Covers - Polished

Holley's new 2-Piece LS valve covers are a great way to update the look of your LS engine without the use of complicated adapter systems or the hassle of remote coil relocation. These modular LS valve covers feature an OE height, internally baffled LS valve cover base with integrated coil mounts for popular Gen I and Gen V style LS coil bodies, and a vintage style finned overcover that hides the unsightly LS coils and messy wiring harness - allowing the full performance benefits of coil-on-cover ignition setups without the robotic styling. Each modular coil cover features a simplified version of our Vintage Series style fins that seamlessly blends with other finned Holley dress-up accessories such as our LS valley covers and 14" round air cleaners. The coil cover also features cast-in provisions for the spark plug boots and coil wiring harness so no extensions or custom wiring is required.

Each 2-Piece LS valve cover set includes a low-profile billet oil fill cap, hardware and spacers for mounting both versions of LS coil bodies, and 12-point dress up hardware and rubber grommets for the coil covers. These modular LS valve covers are now offered in 5 unique finishes: natural cast, polished, satin black, factory orange, and gloss red (black, factory orange and gloss red sets feature machined fins).

  • Cast aluminum 2-Piece LS valve covers designed to mount and hide both Gen I and Gen V style LS coil bodies
  • Retain the performance of factory coil-on-cover ignition without the unsightly styling
  • Base fits LS1, LS2, LS3, LS6 and LS7 engines with clearance for .750” lift cam with stock style rocker arms
  • Base features internally baffled ventilation system
  • Coil cover features Holley vintage style fins and cast-in wiring provisions
  • No coil relocation, wire harness extensions, or custom spark plug wires required
  • Includes low-profile billet oil fill cap
  • Includes all necessary coil mounting and dress-up hardware

 


Billet Aluminum Front Single Engine Mount
Your Price:
$529.99

Billet Aluminum Front Single Engine Mount for LS Motors

625-8529

In the world of professional offshore powerboat racing the top teams are always looking for ways to save weight without sacrificing performance and durability Hardin Marine knows there is no better way to test a product than to expose it to the abuses and demands of full blown racing While tested in extreme conditions these mounts are still right at home in a recreational pleasure boat. 
 
While bearing the same nominal measurements as the factory Mercury Racing engine mounts that’s where the similarities end. These engine mounts are CNC machined from aero space grade  6061-T6 billet aluminum. Front mounts feature our exclusive billet engine block mounting pads. These pads form a structural bridge like connection to the base of the engine mount. They also provide for an optional speedy engine removal option while the base mount stays in the boat.Next the mounts are machined to accept precision stainless steel bushings in the mounting hole locations to ensure a secure fit and prevent premature wear. After construction of the mounts they are then black hard coat anodized for corrosion resistance and long life.
 
So if your looking for the strongest and lightest engine mount option (half the weight of conventional steel mounts) then there is no better choice than these mounts.  Available in 4 configurations, the shipping mounts are commonly used in catamaran hulls, while the staggered or side by side mounts are perfect for vee bottom installations.  

NOTE: THESE ARE RAW FINISH


LS Jet Boat Rail Kit
Your Price:
$329.99

LS​ Retro-Fit Engine Mount​s for Mercuiser Applications

625-8545

GM LS Marine engine conversions have grown at a speed no one could have gauged until now. Hardin Marine has been at the forefront of the LS marine engine movement for the past number of years bringing to market a cooling system and exhaust option.

But one hurdle of the engine swap on popular Bravo/Alpha applications has left boaters to fend for themselves on solutions or makeshift homegrown engine mount remedies. So the folks at Hardin took to build a direct replacement engine block mount that allows a popular GM LS1, LS2, LS3 to be dropped right back onto the OEM Stud factory mount or the High Performance Hardin Marine stud mount #620-52380.


LS Jet Boat Rail Kit
Your Price:
$859.99

Marine GM LS Engine Swap System for Jet Boat Applications

625-8536

Marine GM LS Engine Swap System for Jet Boat Applications

The GM LS based engine family has already dominated the automotive industry and has quickly become the high performance standard in the performance boating world. Hardin Marine has taken the guess work out of this by developing the most versatile and complete LS Marine engine swap components found anywhere. Making installing a LS in your favorite boat a reality.

The GM LS 1,2,3, and 6 series engines can use this Solid Works/CAD engineered engine swap system for the mounting of a GM LS series engine into a popular Jet driven power boat. The engine mounting swap rail Kit is perfect for the boater that wants to make the switch to modern efficient engines.

Manufactured from 6061 T-6 aluminum and CNC machined from 3/8" thick motor mounts are 26" wide and have an (optional) provision for a alternator mount. The engine mounts sit on top of heavy duty 2-1/2" wide aluminum stringer rails, Comes complete with fasteners.

Note: Spun aluminum flywheel cover, PTO adapter are sold separately.


LS Jet Boat Rail Kit
Your Price:
$599.99

Marine GM LS Engine Front and Rear Mounting Plates

625-8546

Marine GM LS Engine Front and Rear Mounting Plates

The GM LS based engine family has already dominated the automotive industry and has quickly become the high performance standard in the performance boating world. These brackets make installing a LS in your favorite boat a reality.

The GM LS 1,2,3, and 6 series engines can use these Solid Works/CAD engineered engine mounting brackets. These engine mounts are perfect for the boater that wants to make the switch to modern efficient engines.

Manufactured from 6061 T-6 aluminum and CNC machined from 3/8" thick motor mounts are 26" wide and have an (optional) provision for a alternator mount.

Note: These are mounting plates only. No other hardware is included.


Big Block Chevy Closed Cooling Kit Up To 650HP
Your Price:
$1,999.99

GM LSA Closed Cooling System for Engine and Intercooler

625-458

These are the same coolers OEM Engine manufactures use on their LSA Marine engine conversions. The OEM manufacturer builds their own bracketry and it IS NOT available. So if you plan on buying these units each has a mounting bolt pad but you will need to build YOUR OWN bracketry. If you do not understand closed cooling seek a professional engine builder. There is NOT additional specs available what you see is what we sell we have attached plumbing instructions and some diagrams to assist. They are sold as tanks ONLY for both the engine and the intercooler. Seek a knowledgeable professional for installation.


Big Block Chevy Closed Cooling Kit Up To 650HP
Your Price:
$1,599.99

LS1, LS2, LS3 and LS6 Closed Cooling Kit - Copper / Brass

625-4574

LS1, LS2, LS3 and LS6 Closed Cooling Kit - Copper / Brass

While there are numerous universal OEM closed cooling kits, this is not one of those. This is a true custom engineered and developed closed cooling system designed around new LS1, LS2, LS3 and LS6 applications. The kit is perfect for engines making up to 650 horsepower.

We offer the closed cooling tank version with a pre-primed coat, where you can paint-to-finish. This allows you to customize it to your engine for the ultimate in appearance and durability. This High Performance Closed Cooling kit is designed for applications with horsepower levels to 650HP.

The Kit comes with: Tank, Brackets, Hoses, and Thermostat Housing.

NOTE: Will not work with port side mounted sea pumps 625-4116, 625-4117.


GM LS Series Engine Dual Stage Sea Water Pump
Your Price:
$1,199.99

GM LS Series Engine Dual Stage Sea Water Pump

625-4117

Hardin Marine is the first to bring a engine specific sea water pump for the popular LS series of engines. This dual stage sea water pump was designed around the 5.3 ,6.0, and 6.2 liter generation engine platforms. The pump uses Hardin Marine's Extreme Lifetime Series stainless steel impeller housing as well as a proprietary short body construction that allows the necessary access or clearance for the engines factory engine mounting pads when the pump is installed. The pump is designed to mount to the engine blocks factory A/C mounting bosses while positioning the billet aluminum serpentine pulley in line with OEM crankshaft pulley. The billet mounting bracket provides the two necessary idlers that allow this pump to be incorporated into most factory automotive serpentine accessory drive systems. The Sea pump features female (2) 1" NPT  and (1) 1-1/4" common inlet and outlet ports for ease of plumbing convenience.

Note: Fits OEM GM LS Corvette / CTS-V / G8 automotive balancer spacing with 1-1/2" offset (NOT Truck or F-Body balancer)

LS Sea Pump Assembly
Your Price:
$895.99

GM LS Series Engine Single Stage Sea Water Pump

625-4116

Hardin Marine is the first to bring a engine specific sea water pump for the popular LS series of engines. This single stage sea water pump was designed around the 5.3 ,6.0, and 6.2 liter generation engine platforms. The pump uses Hardin Marine's Extreme Lifetime Series stainless steel impeller housing as well as a proprietary short body construction that allows the necessary access or clearance for the engines factory engine mounting pads when the pump is installed. The pump is designed to mount to the engine blocks factory A/C mounting bosses while positioning the billet aluminum serpentine pulley in line with OEM crankshaft pulley. The billet mounting bracket provides the two necessary idlers that allow this pump to be incorporated into most factory automotive serpentine accessory drive systems. The Sea pump features female 1" NPT inlet and outlet ports for ease of plumbing convenience.

Note: Fits OEM GM LS Corvette / CTS-V / G8 automotive balancer spacing with 1-1/2" offset (NOT Truck or F-Body balancer)

LS Crossover and Thermostat
Your Price:
$399.99

GM LS1 - LS3 Thermostatic Control Crossover Cooling System for Non-Circulating Pump Applications

625-4535

GM LS1 - LS3 Thermostatic Control Crossover Cooling System for Non-Circulating Pump Applications

AT last a cooling system solution for adapting the popular GM LS engine into any Jet Boat or application with an external water pump source. This system allows removal of the Automotive engine mounted water circulation pump and provides both water inlet/outlet and temperature control through the integrated thermostat assembly. Clean, simple, and reliable the perfect solution for retrofitting the LS modern engine into a jet boat or any boat not utilizing the OEM circulating pump.

WARNING**** will not work with Variable Valve Timing covers.


High Performance 1.4KW LS marine starter
Starting From:
$269.99

This Part has options, please click the button below to order.

High Performance LS Marine Starter

620-312 + Option(s)

This is a "TRUE" High Performance 1.4KW LS marine starter designed for use on late model GM LS Chevrolet marine engine application including 4.8,5.3,6.0,6.2, and 7.0 Litre versions. The application has a slight off-set and uses the OE bolts for installation and features Genuine precision N.D starter motor coupled to patented design billet mount. Available in Short and Long gear versions

Technical specs:
  • Rotation CW
  • kW 1.4
  • Gearing 4.44 to 1
  • Rotatable Yes
  • Voltage 12v

USCG Approved (SAE J1171)


Holley LS Hi-Ram EFI Manifold
Your Price:
$971.95

Holley LS Hi-Ram EFI Manifold

710-300-124

Holley LS Hi-Ram EFI Manifold

  • Runner Length – 6.29”, As-Cast Runner Cross-Sectional Area – Tapered 4.67in² to 2.84 in²
  • Throttle Body Flange Location, with 92/102mm EFI Plenum Top : Height – 8.42” (from engine block lifter valley cover flange), Longitudinal Location – 3.84” (forward from engine block front flange), Angle – 25 deg. (down from vertical)
  • Plenum Top Gasket Type – 3/32” Round O-ring Cord
  • Mounting Flange Gasket Type – Standard LS3 Molded O-Ring
  • Port Size – 2.49” Height x 1.21” Wide
  • Total Height with 92/102mm EFI Plenum Top – 12.32” to the lifter valley cover flange on engine block.
  • Base Plenum Top Mounting Flange Height – 8.42” to the lifter valley cover flange on engine block.
These parts should be used for the following applications: Racing/Performance/Street Rodder where hood restrictions are NOT a consideration. Top can be mounted forward or backward. Holley EFI LS main harnesses have a map sensor connecter designed for use with an LS1/2 style map sensor. The 558-416 is an adapter harness that can be used to adapt any LS harness that uses a LS1/2 MAP sensor connection to a LS3 MAP, which is recommended for this manifold.

LS Crossover and Thermostat
Your Price:
$389.99

GM LS1 - LS3 Thermostatic Cooling System for Freshwater Sterndrive Applications

625-4530

GM LS1 - LS3 Thermostatic Cooling System for Freshwater Sterndrive Applications

As Hardin Marine continues the quest towards new product development they have designed an easy to install thermostatic cooling system for freshwater raw water cooled engine applications. This system allows use of an OEM circulating style water pump and multiple accessory drive kits to to be used while providing the necessary thermostat assembly for temperature control. This is perfect for retrofitting a GM LS based engine into most popular sterndrive engine applications using a sea water pump assembly. Precision CNC machined and anodized satin finish make for an attractive compact fitment. Each unit features a 160 degree thermostat while other heat range thermostats and a bypass hose assembly is sold separately.


LS Crossover and Thermostat
Your Price:
$159.99

Bypass Hose Kit for GM LS1 - LS3 Thermostatic Cooling System

625-4536

Bypass Hose Kit GM LS1 - LS3 Thermostatic Cooling System 

For use with 625-4530 Thermostatic Cooling System.