top of page
Piper Cams | Duratec Single Valve Spring Set | Ford Fiesta ST 150

Piper Cams | Duratec Single Valve Spring Set | Ford Fiesta ST 150

SKU: VSSDUR
TECHNICAL DATA
 
This is a Piper Cams double valve spring assembly engineered for high-performance Ford/Mazda Duratec engines (1.8L, 2.0L, 2.3L). It's a proprietary dual-rate spring system characterized by its concurrent, concentrically nested helical springs, designed to provide a high-load, progressive-rate profile for extreme valve lift applications.
 
Unique Technical Specifications & Design Rationale:
  • Composite Spring Rate: The primary (outer) spring delivers a nominal rate of 42 N/mm (242 lbf/in), but the system's functional rate is progressive. The initial low-load segment is managed by the inner spring, with the full composite rate engaging as lift increases, optimizing stress distribution and harmonics.
  • Precision Geometry: With a nominal installed inner diameter of 18.08mm, the set is engineered for a tight clearance fit on standard retainers. The 25.6mm nominal outer diameter ensures compatibility with standard cylinder head pockets without machining, while the 23.5mm crush height defines the absolute coil bind limit for safe operation.
  • High-Lift Kinematics: The 38mm fitted length and specified crush height yield a maximum theoretical safe lift of 14.5mm (38mm - 23.5mm = 14.5mm), providing a designed safety margin over the stated 14mm operational capacity. This is critical for preventing coil bind at the advertised >11mm lift threshold.
  • Dual-Seat Pressure Management: The 48 lbf (22 kg) seat pressure is a composite load from both springs at installed height. This dual-spring design mitigates surge at high RPM by having two distinct natural frequencies, damping resonant harmonics that can cause valve float in single-spring setups.
  • Material & Finish: (Implicit from performance spec) Springs are likely manufactured from chrome-silicon or high-tensile chrome-vanadium wire, shot-peened for fatigue resistance, and possibly heat-set (presprung) to maintain rate stability over temperature cycles. The inclusion of caps (likely spring seats/shims) and seals indicates a complete retrofit kit for maintaining correct installed height and preventing oil ingress down the valve guide.
 
Application-Specific Engineering:
This assembly is not a direct OEM replacement but a performance-scaled system. It replaces the OEM single spring with a tuned dual-spring damper system, effectively shifting the engine's valve train resonance frequency higher. This allows for the use of aggressive cam profiles (>11mm lift) by controlling valve acceleration and deceleration at the limits of piston-to-valve clearance in these engines. The design prioritizes high-cycle fatigue endurance under the extreme stress of repeated high-velocity compression, making it suitable for forced induction or high-RPM naturally aspirated builds where valve control is paramount.
 
In summary, this Piper Cams set is a densely packaged, frequency-tuned valve spring damper system that provides the necessary force progression and harmonic damping to maintain valvetrain integrity at the kinematic limits of the Duratec platform.
    £246.65Price
    Excluding VAT
    Quantity

    Returns Information: Thank you for choosing our products. We strive to provide excellent customer service, and we want to ensure your satisfaction with your purchase. Please review our return policy below: Timeframe: Our return policy lasts for 14 days from the date of delivery. If 14 days have passed since your purchase, we regret to inform you that we cannot offer a refund or exchange. Eligibility: To be eligible for a return, your item must meet the following criteria: It must be unused and in the same condition as when you received it. It should be in its original packaging, suitable for resale. The buyer is responsible for the return postage costs, and we recommend using a tracked and insured service. Restocking Fee and Outbound Postage: Please note that all returns are subject to a 10% restocking fee. Additionally, outbound postage fees will be deducted from the refunded amount. The handling fee covers the costs incurred in processing credit card payments, as well as postage and packaging costs. Exemptions: Certain types of goods are exempt from being returned. These items cannot be refunded once a special, non-stock item has been processed. Return Process: To initiate a return, please contact us as soon as possible. We will provide you with the necessary instructions to complete the return. Condition of Returned Items: Please ensure that any items being returned are not damaged and are in "as new" condition. Damaged or incomplete items may be subject to a partial refund. Refunds: Once we receive your returned item and complete the inspection, we will send you an email to notify you of its receipt. We will also inform you of the approval or rejection of your refund. If your refund is approved, we will process it, and the credit will be automatically applied to your credit card or original method of payment within a specific number of days. Sale and Group Buy Items: Please note that only regular-priced items are eligible for refunds. Unfortunately, sale and group buy items cannot be refunded. Damaged or Defective Goods: In the event that your goods arrive damaged or incomplete, please notify OC Motorsport within 24 hours of delivery. If we have mistakenly supplied incorrect parts, we will first attempt to provide you with the correct parts. If the correct products are unavailable, we will reimburse you the full purchase price within 14 days. However, please note that OC Motorsport is not responsible for any labour charges incurred during the fitment or removal of suspected incorrectly ordered or supplied parts. Warranties: Generally, warranties are provided by the product manufacturer and not by OC Motorsport. Therefore, we recommend reaching out to the product manufacturer as the primary point of contact. If you encounter any difficulties in contacting the manufacturer, please feel free to reach out to us, and we will do our best to assist you. Thank you for taking the time to familiarize yourself with our return policy. If you have any further questions or require assistance, please don't hesitate to contact us.

    360_F_423928952_lL1wq5ia7bR3j9yZohSc4bcvr9qePAB1.png
    bottom of page