Description
This is the genuine Cosworth DR4601 valve spring, manufactured by NHK in Japan from high-strength steel with surface modifications that enhance fatigue strength and reliability, crucial for engine performance and longevity.
*** DUE IN STOCK BEGINNING OF SEPTEMER 2025, PRE-ORDER NOW ***
A nested twin spring design like the Cosworth DR4601 valve spring can offer a proven solution to the problem of spring surge. The stiffness of the combined spring varies with length, hence the inner and outer springs will have different natural frequencies which helps to avoid the onset of surge. In addition, the outer diameter of the inner spring and the inner diameter of the outer spring are chosen so as to create a small amount of interference between the two springs. This interference will provide a means of damping, allowing unwanted energy to be converted to heat from the friction between the two springs, again helping to offset the unwanted effects of spring surge.
The Cosworth DR4601 valve spring was originally designed for use on the DFV series of engines, but it has since been used in many other race & high performance engine applications. We also stock the PR8121 non-interference valve spring, as used on Cosworth BD-series engines.
Dimensions:
Inner Spring
- Spring Rate = 23.85 N/mm
- Free Length = 38.8 mm
- Solid Length = 19.6 mm
- Outer Diameter = 23.4 mm
- Inner Diameter = 17.2 mm
- Wire Diameter = 3.1 mm
- No of Coils = 6.54
- Winding = Left Hand
Outer Spring
- Spring Rate = 50.48 N/mm
- Free Length = 38.4 mm
- Solid Length = 20.4 mm
- Outer Diameter = 31.9 mm
- Inner Diameter = 23.5 mm
- Wire Diameter = 4.2 mm
- No of Coils = 4.99
- Winding = Right Hand
