With over five decades of expertise in radiator manufacturing, CSF stands as a trusted leader in automotive cooling solutions. The CSF 03-05 Honda Civic Si High-Performance All-Aluminum Radiator exemplifies this legacy, engineered to provide superior cooling performance for your Civic, whether on the street or the track. This radiator is essential for high horsepower builds and race vehicles that demand enhanced cooling efficiency in demanding motorsports environments.
This radiator features a robust 2-Row, 42mm core, incorporating CSF's exclusive B-Tube Technology. Unlike conventional oval "O" type radiator tubes, CSF employs a uniquely engineered "B"-shaped tube. These B-tubes are meticulously formed and seam-brazed to ensure a strong, airtight seal. This innovative design allows the use of thinner, lighter aluminum material without compromising strength, resulting in improved cooling efficiency compared to traditional welded "O" tubes.
The B-tube design increases the heat transfer surface area by approximately 15% over standard tubes, effectively delivering the cooling capacity of two smaller tubes within the same spatial constraints. This configuration facilitates dual liquid laminar flow, optimizing heat dissipation. Complementing this technology, CSF integrates ultra-efficient multi-louvered fins that are precisely aligned to maximize airflow through the radiator core. Each fin specification is carefully calculated and validated through rigorous wind-tunnel testing to ensure maximum heat rejection efficiency.
Installation is straightforward with the CSF Civic radiator’s true "Drop-in fit" design, requiring no modifications. The radiator includes CNC-machined and welded OE-style brackets for enhanced durability and precise fitment. The inlet and outlet connections are engineered to match original equipment manufacturer (OEM) specifications, allowing seamless reuse of OEM hoses or aftermarket components. This ensures a hassle-free upgrade without compromising compatibility with existing systems such as the AC condenser, mounting brackets, and fan shroud.
Features
- 2-Row 42mm Core (Dual Core) Featuring CSF's Exclusive B-Tube Technology
- Core Features an Ultra-Efficient Fin with 6.5mm Fin Height and Multi-Louvered Design for Maximum Surface Area Contact
- CNC Machined "Quick-Connect" Inlet/Outlet Connections for Precise Fit and Easy Installation
- CNC Machined Brackets and Fittings for Superior Durability and OEM-Quality Fitment
- All-Aluminum Race Style Drain Plug for Enhanced Durability and Maintenance Convenience
- 1-Hour "Mirror Finish" Hand Polish for Corrosion Resistance and Aesthetic Excellence
- "Drop-in Fit" Requiring No Modifications to Install - Compatible with All OEM Attaching Components Including "Quick Connect" Hoses, AC Condenser, Mounting Brackets, and Fan Shroud
Applications
| Year Range | Make | Chassis Code | Model | Trim | Engine / Trans / Etc | Notes |
|---|---|---|---|---|---|---|
| 2002-2005 | Honda | EP3 | Civic | Si | 2L L4 (Manual) | - |
OEM Part Numbers
- Honda: 19010 PRA 003
- Honda: 19010-PRA-003
- Honda: 19010PRA003
- Honda: 19010 PNF 003
- Honda: 19010-PNF-003
- Honda: 19010PNF003
Warranty
Cooling Systems and Flexibles, Inc. (CSF) guarantees its High-Performance Cooling Systems under normal use and service to the original purchaser of the vehicle in which the product was initially installed. This warranty reflects CSF’s commitment to quality, reliability, and customer satisfaction. For comprehensive warranty details, please visit our Warranty Page.
SKU# 3022 Warranty Term: 2 years
In summary, the CSF 03-05 Honda Civic Si High-Performance All-Aluminum Radiator delivers exceptional cooling performance through advanced engineering and premium materials. Its precise fitment, durable construction, and innovative B-Tube Technology make it the optimal choice for enthusiasts and professionals seeking reliable temperature management for their Civic Si. Trust CSF to maintain your engine’s optimal operating temperature, ensuring longevity and consistent performance under all driving conditions.
Unless explicitly stated otherwise, all products sold by R44 Performance Limited are designated RACE ONLY and are solely for competition or off-road use limited to racing formally sanctioned by a recognized racing organization. Any other use, including recreational off-road use, may violate local, state, and Federal laws. R44 Performance Limited does not implicitly or explicitly confirm the legality of using any products it sells on public roads; that is entirely the responsibility of the consumer.
It is the responsibility of the customer to check with all federal, state local and environmental laws before ordering and installing a product. R44 Performance Limited is not responsible for any fees, fines or costs that a customer may incur as a result of failing to check with federal, state, local or environmental laws before ordering and installing a product.
We get a large number of custom orders and requests everyday, so as a result it is not always possible for us to keep every item in stock at all times in our warehouse. If you require the item urgently please contact our sales team here to check the stock before you make your purchase.
We totally understand if you're not certain a part will be compatible with your car, so we highly recommend contacting us here with your query. Our friendly sales team will then be in touch to confirm if this part is the correct part you are looking for.
All in stock products ship the same day if ordered before 2pm GMT
For out of stock items we will contact you with an estimated wait time if not otherwise specified above.
We offer worldwide shipping on all products. If upon receiving your product you wish to return; we offer a 30-day returns policy. For our in-depth returns information please follow the link. "R44 Returns Policy
All of our products come with a standard warranty of 1-3 years. This is dependant on the type of product however. For more details please see our warranty page here.
PLEASE NOTE
- Orders with both in-stock and backorder or out-of-stock products will be dispatched once all products are available to ship together.
- Contact our sales team if you want your parts fitted to your vehicle at our London workshop.
- Shipping estimates are based on courier delivery times and don't include time to despatch from our warehouse.





