



Eliminate head gasket vulnerabilities and valvetrain fatigue under the absolute harshest operating conditions. The Workhorse Plus tier cylinder head for the Kawasaki 70ZV wheel loader (Cummins QSB5.9 24-valve electronic engine) is engineered specifically for severe-duty industrial applications where equipment breakdown and job site downtime are cost-prohibitive. Assembled using a renewed, pressure-tested OEM core and top-tier internal components, this premium head delivers maximum protection against extreme cylinder pressures, punishing thermal expansion, and continuous high-torque duty cycles.
While the Workhorse tier introduces a critical O-ringed deck, the Workhorse Plus upgrades the assembly with premium, heavy-duty valve springs and reinforced retainers. This severe-duty valvetrain configuration prevents valve float and spring fatigue during sustained full-load operation, managing the elevated exhaust backpressures common in industrial turbocharger setups. The result is absolute valvetrain stability and precise tracking when your loader is working at peak operational capacity.
Remanufactured Casting: Built from a premium OEM 24-valve core casting that has passed rigorous diagnostic testing and is machined to like-new industrial specifications.
Precision O-Rings: To combat severe thermal expansion common in high-utilization heavy equipment, precision O-rings are machined directly into the deck surface. This mechanical modification locks the head gasket securely in place, completely eliminating the risk of combustion leaks under extreme loads.
New Valves: Equipped with all-new, high-quality intake and exhaust valves, verified for precise seating and clearance.
New Injector Cups: Pre-installed new injector cups ensure a permanent, air-tight fuel seal and eliminate the threat of internal coolant contamination.
This severe-duty head undergoes an intensive inspection and upgrade protocol to guarantee every critical industrial metric is met.
40 PSI Pressure Testing: Following the machining process, every cylinder head is pressure-tested at 40 PSI to verify zero structural leaks and absolute casting integrity.
Blow-Proof Plugs: Threaded, blow-proof plugs are installed into the top of the head for superior safety, replacing factory pressed-in freeze plugs that regularly fail during severe thermal spikes.
Final Quality Control: The head undergoes a meticulous final cleaning and rigorous quality control checking. A comprehensive specification sheet is generated, using a profilometer to record:
Valve Recessions
Stem Heights
Installed Spring Heights
Spring Pressures
Keeper and Lock Positions
Roughness Average (RA) Surface Finish
Choate Engineering Performance incorporates structural updates to resolve common factory vulnerabilities of the 5.9L 24V Cummins industrial cylinder head, significantly extending operational lifespan:
Optimal Sealing Surface: The deck is resurfaced to strictly meet or exceed OEM specifications for Roughness Average (Ra), maximizing the sealing surface performance for the head gasket.
Valve Train Geometry Alteration: The head is custom blueprinted to adjust valve height and valve recession, optimizing geometry for high-stress industrial applications.
Lifter and Bridge Longevity Fix: Valve stem heights are precisely machined to remove excessive preload on the lifters, a critical adjustment that dramatically reduces wear and extends the service life of the bridges, crossheads, lifters, and camshaft.
Optimized Flow and Sealing: Valve seats are cut with an industrial three-angle profile to optimize engine efficiency and ensure an airtight seal.
Valve Prep: Valves are reground and margins are meticulously inspected to guarantee proper sealing against the new seats.
All-New Wear Parts: New valve stem seals, valve seats, valve guides, and injector cups are installed across the entire assembly.
Our manufacturing protocol begins with an intensive cleaning and stress-relieving process to ensure a flawless casting:
Magnetic Particle Inspection (MPI): Every single core is subjected to MPI testing to scan for microscopic cracks or subsurface structural imperfections common in high-hour castings.
Thermal Stress Relieving: Castings undergo a thermal baking process in a specialized furnace to eliminate residual industrial oils and grease by converting them to ash.
Material Relaxation: The head is shot-blasted to strip away rust and scale. This vital step relaxes the cast iron before any precision machining takes place.
Thread Restoration: All broken factory bolts and studs are professionally removed, leaving all holes clean, chased, and ready for a seamless installation.
PLEASE READ AND FILL OUT THE WARRANTY REGISTRATION FORM TO ACTIVATE THE WARRANTY.

Supplied with every engine is a complete copy of our warranty with an attached warranty registration form. This form can also be found here. Once filled out:
Then email a copy of each document within 45 days from the time of purchase to warranty@choateperformance.com. You should also retain a copy for your records as it may be required to assist with a warranty concern.
MODEL C STANDARD WARRANTY
1 Year / Unlimited Miles

THIS WARRANTY IS WITH THE PURCHASE OF THE INSTALLATION PACKAGE AND IS FOR THE ENGINE/WORKMANSHIP ONLY. NO LABOR PAYOUTS.
EXTENDED COMMERCIAL WARRANTIES ARE NOT AVAILABLE ON WORKHORSE, CASSQUATCH RACE SERIES, OR MODEL C ENGINES.
Remanufactured Heads — 6 Months
PARTS ONLY

Cylinder heads are warranted to be free from defects in material and workmanship. This warranty does not cover cylinder heads that are damaged due to improper installation, overheating, abuse, or accident.
Short Block Engines

Warranty coverage for Short Block engines does not include labor payout. We do not cover fluid leaks on any Short Block builds.
DAILY DRIVER WARRANTY
5 Year / 100,000 Miles

THIS WARRANTY IS NOT A FULL COVERAGE WARRANTY. PLEASE REVIEW YOUR WARRANTY CAREFULLY.
Labor rate for PREFERRED DEALER ONLY is a higher shop rate using Mitchell flat rate time.
WORKHORSE SERIES ENGINE
5 Year / 100,000 Miles

THIS WARRANTY IS NOT A FULL COVERAGE WARRANTY. PLEASE REVIEW YOUR WARRANTY CAREFULLY.
Labor rate for PREFERRED DEALER ONLY is a higher shop rate using Mitchell flat rate time.
YOUR CASSQUATCH RACE ENGINE
6 Months / 3,000 Miles
PARTS ONLY

THIS WARRANTY IS NOT A FULL COVERAGE WARRANTY. PLEASE REVIEW YOUR WARRANTY CAREFULLY.
CHOATE ENGINEERING PERFORMANCE COMMERCIAL WARRANTY
1 Year / 20,000 Miles

THIS WARRANTY IS NOT A FULL COVERAGE WARRANTY. PLEASE REVIEW YOUR WARRANTY CAREFULLY.
Labor rate for PREFERRED DEALER ONLY is a higher shop rate using Mitchell flat rate time.
CHOATE ENGINEERING PERFORMANCE EXTENDED COMMERCIAL WARRANTY
3 Year / 60,000 Miles

THIS WARRANTY IS NOT A FULL COVERAGE WARRANTY. PLEASE REVIEW YOUR WARRANTY CAREFULLY.
WARRANTY COVERAGE DETAILS
This warranty will cover remanufactured Short and Long-Block engines that are built by Choate Engineering Performance unless otherwise stated. From this page on, engines will be referred to as “unit(s)” and/or “engine(s)” unless otherwise stated. Fuel pump, injectors, and turbo warranties, and warranties on all accessories, are covered by the supplying manufacturer’s warranty.
FOR PREFERRED DEALERS ONLY: LABOR RATE IS SET AT A HIGHER RATE PER HOUR UP TO A MAXIMUM OF $2,500, NO EXCEPTIONS.
THE LIMITED WARRANTY WILL BE VOID AND WILL NOT APPLY TO DEFECTS OR FAILURES CAUSED BY THE FOLLOWING:
BUYER ALSO ACKNOWLEDGES THAT PROPER MAINTENANCE PROCEDURES ARE REQUIRED TO KEEP THE UNIT IN PROPER WORKING ORDER. CHOATE ENGINEERING PERFORMANCE WILL NOT ASSUME ANY RESPONSIBILITY FOR THE COST OF THIS ROUTINE MAINTENANCE.
Buyer acknowledges the following:
This warranty will not cover damages caused by the following for remanufactured engines:
Choate Engineering Performance limited warranty will end after the expiration of time or mileage from the date of the original invoice. Any repairs or replacements will not extend the warranty. The buyer shall be responsible for all defects thereafter, regardless of cause. Choate Engineering Performance limited warranty is in lieu of all other warranties expressed or implied.
The buyer agrees Choate Engineering Performance will not be responsible for:
TO QUALIFY FOR THE 5 YEAR / 100,000 MILE WARRANTY YOU MUST FOLLOW ALL INSTRUCTIONS AND REPLACE ALL PARTS SPECIFIED.
THIS WARRANTY IS TRANSFERABLE THROUGH PRIVATE SALE AND CHANGE OF OWNERSHIP ONLY ONCE IF CERTAIN CRITERIA ARE MET.
CHOATE ENGINEERING PERFORMANCE LIMITED WARRANTY FOR THE WORKHORSE AND CASSQUATCH SERIES ENGINES IS IN ADDITION TO ALL ITEMS LISTED IN THE STANDARD WARRANTY PACKAGE AND SUPERSEDES ALL MILEAGE REQUIREMENTS.
The Limited Warranty specifically does not cover the following:
FREIGHT / SHIPPING CHARGES

CHOATE ENGINEERING PERFORMANCE SHALL NOT BE RESPONSIBLE, NOR SHALL IT PAY ANY FREIGHT/SHIPPING CHARGES.
ADDITIONAL INFORMATION

As consideration for the above warranties, the buyer agrees they will take no action, statement, characterization, or implication regarding Choate Engineering Performance that may in any manner be interpreted as disparaging to Choate Engineering Performance or the reputation of Choate Engineering Performance. Any violation of this is a material breach, entitling Choate Engineering Performance to void any warranty.
