


The 24-valve Cummins ISL series represents a significant leap in heavy-duty diesel performance, delivering the massive torque required for motorhomes, fire trucks, and industrial equipment. However, with 24 valves and increased fueling comes higher cylinder pressures. The ARP 247-4211 kit is the definitive upgrade to replace factory head bolts, which are prone to stretching under the intense demands of high-load or high-boost operation.
Built from proprietary ARP2000® material, these studs offer the ultimate defense against "head lift" and blown head gaskets on the 8.3L and 8.9L 24V platforms.
ARP2000® Super-Alloy: This high-performance material is heat-treated to a tensile strength of 220,000 psi, providing a massive increase in clamping force over the factory "torque-to-yield" hardware.
Superior Fatigue Life: To ensure maximum durability, threads are rolled after the heat-treatment process. This makes the studs roughly 2000% (20x) more resistant to fatigue than standard fasteners.
Maximum Sealing Integrity: Unlike bolts that twist into the block, these studs remain stationary. Clamping force is applied vertically as the nut is tightened, ensuring a more accurate and consistent load across the head gasket.
Precision Machining: Every stud is centerless ground to ensure perfect concentricity. This precision allows for effortless alignment of the cylinder head and gasket during assembly.
The 24-valve ISL is often pushed to its thermal and mechanical limits in heavy-duty applications. Factory bolts are designed for stock power levels and "one-time" use; once they stretch, they lose their ability to maintain a high-pressure seal. This leads to the dreaded "bubbling" in the expansion tank and eventual engine failure.
Upgrading to the ARP 247-4211 ensures that your engine's "bottom end" and "top end" stay fused together. This is the best insurance policy for any ISL owner looking to increase reliability for long-haul towing or performance-tuned motorhome applications.
Installation Tip: Proper lubrication is critical. Use the included ARP Ultra-Torque Fastener Assembly Lubricant on the stud threads and the seating surface of the nut to ensure you reach the correct preload without friction-induced torque errors.
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.