Ferocity02

iTrader: (60)

Is there a need to get heavier valve springs with boost? Or are the springs still sized by the cam and lift? I'm looking into some small turbo cams, around 214 duration and under 0.580" lift, and was considering using Comp 918 or PAC 1518 single beehive springs. I'm looking at 5-10psi, maybe up to 15psi of boost.

denmah

iTrader: (2)

i use 1218s with a zr1 cam, and 22lbs of boost

they have 131lbs of seat pressure

ide say anything over 120lbs will be good, since stock springs are like 60-80lbs at the seat...

nearly any springs you bought for a cam will be better than that or higher than 130lbs ide say

pwrtrip75

iTrader: (8)

Valves require X amount of spring pressure to keep them closed. If you add pressure to that (boost or back pressure) you subtract from the spring.

2 inch intake valve has a surface area of 3.14 square inches (a little less due to stem and valve seat). So 15 psi of boost would equate to 47.1 lbs of force opposing the spring. So if your seat pressure was 125lbs.... with 15 psi of boost (15 x 3.14 = 47.1) you have a seat pressure of 77.9 lbs. (125 - 47.1 =77.9). You will have back pressure in your exhaust also.... so your exhaust valve would have pressure on it also. How much? Turbo size? pipe size? .... varies.
So ya... your valve springs need to be sized for cam size and boost pressure.

Im horrible at math so someone correct me if I have that all back asswards. And 3.14 for an area if a 2" circle? Seems like a lot? I used an online calculator. lol. Anyway the concept is there.

Ferocity02

iTrader: (60)

Math makes sense to me. Is it possible to go overkill on the springs with such a low-lift cam?

chevellepowered

iTrader: (37)

this too is a area i need to learn more about.. i believe my spring are causing me not to make anymore power past 15lbs.. keeps making torque ,but no hp.. i have com cams.. seat pressure is 105lbs... im running 19lbs.... i plan on stronger springs..and back to the dyno

chevellepowered

iTrader: (37)

i would think if you went with a strong strong spring.. you would need to upgrade the lifters and pushrods to handle the extra force..just a guess.

lsturbo

Patriot gold valve spring kit and trick flow universal push rods best bang for your money I'm running this setup with 20 pounds of boost

a4ls2goat

I'm using the lunati dual spring kit. Was fairly cheap at 200$.

Bob@BruteSpeed

iTrader: (16)

If you have ever seen what happens when a single spring breaks, you'll go with double springs. Normally with a dual spring, if one of the springs break, you'll notice a slight miss and can get it fixed without anything catastrophic happening. The Patriot Golds work very well for camshafts under .650 lift. Bob