4R250 Sport Cylinder Head MINI R53 | R52 | R50 | Cooper | Cooper S | JCW

TRACK-DAY UPGRADE
The 4R250 Sport Head is developed for MINI Gen 1 drivers looking to unlock more power and flow from their engine setup. Designed as a performance upgrade over the standard replacement head, it’s ideal for weekend racers and spirited street builds that see regular track use. With improved airflow and upgraded valvetrain components, the 4R250 head offers increased performance and reliability, without compromising drivability. Whether you’re running mild boost, upgraded camshafts, or free-flowing intake and exhaust systems, the 4R250 head is built to support your next-level build.

READY TO PERFORM
Before machining, all cylinder head castings are fully disassembled and meticulously cleaned to remove any residual oil, carbon buildup, or debris from previous use. Each casting then undergoes pressure testing and visual inspection to verify it is free from cracks, warped surfaces, damaged threads, or other potential defects. Only heads that meet our quality standards proceed to the machining stage.

MACHINED TO LAST
The machining process begins with replacing all valve guides with our spec-designed manganese bronze Ultraflow guides, engineered for optimal heat transfer and shaped to support smooth airflow without compromising valve stability. Once installed, each guide is precision-honed to achieve the correct valve-to-guide clearance, ensuring proper lubrication and long-term reliability. The head is then fixtured in our in-house Serdi valve seat machine, where all seats are cut using a custom multi-angle profile tailored to the flow characteristics of OEM 30.3 mm intake valves and oversized 25.2 mm SUPERTECH exhaust valves. After seat cutting, the deck surface is resurfaced to achieve maximum flatness and the ideal finish for a reliable seal with the MLS head gasket. Finally, the cylinder head is thoroughly cleaned to remove any residual debris or oil from the machining process, preparing it for final assembly.

WHAT MAKES PORTING BETTER
Cylinder head porting is a proven method to enhance airflow efficiency and increase power. On the 4R250 head, we apply a targeted approach: the intake runners are pocket-ported to reshape and blend the area beneath the valve seat, improving flow without sacrificing velocity, ideal for engines operating in midrange power bands. The exhaust runners are fully ported to complement the larger SUPERTECH exhaust valves and increase high-load flow capacity. This combination delivers measurable gains in airflow while preserving drivability. All porting work is developed and verified in-house using our flow bench to ensure consistent, real-world improvements in performance.

BUILT TO PERFORM
All 4R250 cylinder heads are assembled using a carefully selected combination of OEM and performance-grade SUPERTECH valvetrain components. The setup includes standard-size 30.2 mm intake valves and +2.3 mm oversized 25.2 mm SUPERTECH exhaust valves to improve flow and exhaust evacuation under load. OEM valve springs, retainers, and keepers are used for reliable control at moderate RPMs, while Viton valve stem seals provide long-lasting oil management.

OPTIONAL CAMSHAFTS
If you're targeting more power from your 4R250 head package, upgrading the camshaft is essential. We offer several camshaft options to suit different setups. For improved low-end torque and drivability, we recommend the CatCams 1302461. For increased high-RPM performance and maximum top-end power, the CatCams 1302469 is the ideal choice. Both profiles provide noticeable gains in power and torque across the entire RPM range.

CYLINDER HEAD INSTALLATION PACKAGE
Simplify your cylinder head installation by adding our Head Installation Package to your order. To ensure maximum performance and reliability from your 4RevisionEngines build, we supply only high-quality components that protect your investment. Each kit includes the correct fluids, a complete set of gaskets, head bolts, and a fresh set of spark plugs, everything required for a clean and efficient install. Compatible with all MINI Gen 1 engines, this package offers the essential parts at a discounted rate, saving you time, cost, and unnecessary hassle.

POWER RATING
The 4R250 Cylinder Head is engineered to support power outputs of up to 250 BHP when combined with the right supporting modifications. These include smaller supercharger pulleys, larger fuel injectors, improved intercooling, colder intake air, and a high-flow exhaust system.

WHAT’S IN IT

Head – OEM machined and pocket-ported casting
Intake Valves – OEM 30.2 mm intake valves
Exhaust Valves – SUPERTECH +2.3 mm (25.2 mm) oversized exhaust valves
Springs / Retainers – OEM valve springs and retainers
Valve Locks – OEM keepers / collets
Guides – 4REVISION manganese bronze Ultraflow valve guides
Valve Seals – Viton valve stem seals
Valve Job – Custom multi-angle valve job for improved flow
Deck Surface – Resurfaced for MLS gasket compatibility
Cleaned – Professionally cleaned and ready for assembly