RND Motorsport Z20let/r/l/h Single upgrade valve springs
Having pushed so far on the Z20 engine , we are using what we know to make the more normal power builds better. Learning more on the subject of how much valve spring you need for what you are doing lets you free up some HP in not driving an over sprung engine. Making the springs more accurately lets you drop the pressure back off a little bit because the real world average spring rate is much closer to what you want, on a less accurate spring you have to make them generally firmer to account for the soft ones still being OK to run. This potentially could mean you are over driving 15 valve springs just to make sure the one weaker spring is still doing its job well.
As with most of our high quality items that we sell, these are UK manufactured by a very reputable company, they are much more used to hitting a less than 1% deviation on spring to spring. This is key to being able to run a much closer to desired spring pressure without so much extra for the sake of it.
Wound from high quality steel , both ends ground flat , micro peened and coated , pretty much everything you can do to a spring to improve its performance and life.
These springs will give you in the region 20% more initial seat pressure than a stock spring , with 10mm of lift then they are about 13% stronger than the stock springs. In some cases the other springs we have measured are around 35% stronger with 10mm lift, fine in some applications but not needed in many others. These springs are set to be just right for most fast road cam applications. If you need a little more spring pressure then a 1mm shim will bump the pressure curve on by 10LBS , we have not required this option on anything we have tested so far.
Free length - 45mm
13.00mm lift before bind using stock valve spring retainer and stock seat.
Max lift recommended 11.5 mm
Installed seat pressure with 34mm install height – 79 LBS +/- 1%
pressure at 10mm lift with 34mm install height – 158 LBS +/-1%
