Opinions wanted on CompCams recommendation...
05-25-2006, 04:31 PM
#13
Originally Posted by aharrold
Jim and Erik, is there any rule of thumb on the cam specs for a supercharger? I'm assuming that there would be diffferences just between say a Radix and a ProCharger due to their own individual characteristics, correct? VHP, which is Crane cams I believe, have one they say is hot for a supercharged application in our trucks. It is quite a bit more lift than the one that the Comp rep steered me towards.
The general rule of thumb for s/cs is a healthy exhaust bias and 0* or negative overlap. The general rule I use for specing the lsa to achieve this is: intake duration + exhaust duration / 4 = lsa. This means the bigger your durations, the wider your lsa has to be.
Roger Vinci knows these genIII motors and what works with them and superchargers. It may or may not be widely known anymore, but Roger does a LOT of testing for Crane and works very closely with them. They have a lot of success with their sc cam combos.
05-25-2006, 04:34 PM
#14
Originally Posted by TBSS
There's really no reason to go dual springs (i.e. 924's) on a mild cam with less than .600" or lift, 918's will do just fine, and you won't have to worry about harmonics with a beehive spring.
Stock retainers and keepers are fine, but it's always good to put in hardened pushrods while you're in there. Comp's steel retainers are nearly identical to stock, so it doesn't make sense to go aftermarket retainers unless you go titanium, which I think is $9B per ounce now.
Stock retainers and keepers are fine, but it's always good to put in hardened pushrods while you're in there. Comp's steel retainers are nearly identical to stock, so it doesn't make sense to go aftermarket retainers unless you go titanium, which I think is $9B per ounce now.
05-25-2006, 04:58 PM
#15
TECH Veteran
I'd go with the XR265HR or the G3XFI261HR15. I'd also stay with the stock rocker arms. Unless you plan to go bigger in the future I'd just go with LS6 springs.
05-25-2006, 05:44 PM
#16
TECH Veteran
Originally Posted by TurboBerserker
While i generally agree here, I'd still say buy springs once, and buy them big enough to handle the lift you think you might run later (i.e. don't get 918s if your planning on a monster cam and FI next year, just get 921s or 924s and be done with it). If those comp retainers are steel, skip them, I thought they were the ti
05-25-2006, 05:46 PM
#17
TECH Veteran
Originally Posted by zippy
I'd go with the XR265HR or the G3XFI261HR15. I'd also stay with the stock rocker arms. Unless you plan to go bigger in the future I'd just go with LS6 springs.
05-25-2006, 10:43 PM
#18
TECH Veteran
The XR265HR
Part # 54-424-11
212/218 @ .050
.558/.563
115 LSA
The G3XFI261HR15
Part # 54-451-11
208/212 @ .050
.554/.558
115 LSA
The first will have more up top and be stronger from around 3800 and up with recomended shift points of 6400 (1-2), 6200 (2-3), and 6000 (3-4).
The second will have more power from off idle to shift point than the stock cam with recomended shift points of 6200 (1-2), 6100 (2-3), and 6000 (3-4).
Either would be fine with the LS6 spring kit from GM Performance parts which is cheaper and a much quieter spring kit. The 918's have that typewriter sound to them.
Part # 54-424-11
212/218 @ .050
.558/.563
115 LSA
The G3XFI261HR15
Part # 54-451-11
208/212 @ .050
.554/.558
115 LSA
The first will have more up top and be stronger from around 3800 and up with recomended shift points of 6400 (1-2), 6200 (2-3), and 6000 (3-4).
The second will have more power from off idle to shift point than the stock cam with recomended shift points of 6200 (1-2), 6100 (2-3), and 6000 (3-4).
Either would be fine with the LS6 spring kit from GM Performance parts which is cheaper and a much quieter spring kit. The 918's have that typewriter sound to them.
05-25-2006, 11:19 PM
#19
Originally Posted by TBSS
Most people here will never need anything more than 918's. You only need duals when you go over, what - .600" of lift? We could probably count on one hand the number of people who run (or plan on running) a cam with that much lift. Usually if you're going that big in the cam department, you're going with heads, too, which kind of eliminates the spring issue, right?
Not necessarily. Parish is running stock 317s with springs
plus you can get cheap springs if you do upgrade the heads and swap. I know at least on person who goes over .600 