Black LS-14

iTrader: (1)

I am in the process of having a 418 stroker built. The build consist of:

LS3 block, Callies 4" crank, TSP H-beam rods, TSP/Wiseco 4.085" -10cc pistons, SDPC ported 243 heads milled .005", LS9 head gaskets, 239/251 .623"/.623" 112+2 cam.

With all that Ive figure my static compression ratio right at 11.3:1 with the LS9 gaskets. From what I can figure though, my dynamic compression ratio is gonna be over 10:1 with this cam. Everything I have read is telling me that a dynamic over about 9:1 is too much on 93 pump gas. With that said, I know that Im not the only one who has built a 4" stroke LS with over 11:1 and a cam with even shorter intake duration or LSA than me. Comp spec'd a 235/243 cam and TSP recommended an MS3.

Im I gonna be okay or do I need to look at lowering my compression or changing cams?

Thanks in advance!!

Gray86hatch

iTrader: (83)

I would consult someone to do a real custom cam. Calling comp for a recommendation is like calling summit.

Flowtech induction does my stuff.

Tim

racerx_72

I have a 416ci with 11.7 and Martin @ Tick performance help me with my cam. Give him a call he's good at that stuff

jegten

iTrader: (22)

if you don't mind, what is the chamber size on the heads? what is the thickness of the LS9 gasket? that looks like an lsl cam or not?
i'll check in a little later. i had a similar setup to this, but my pistons were -4cc, and the heads were the TFS 235 with a 68 cc chamber, iirc. cam wasn't far off from yours. my scr was ~11.68.

badassracing

iTrader: (13)

You're probably using IVC @ 050 instead of advertised to figure dynamic compression.

MertezWS6

iTrader: (8)

I think you'll be fine. Im running a very similar setup. 418 with LS3 70cc chamber heads, LS9 gaskets with a -2.7cc piston though. My compression is 11.5 with 8.5 dynamic roughly. Im running a similar cam as well 114 lsa. You forgot to mention the rod length

newschool72

iTrader: (12)

Im pretty sure you did the dynamic formula wrong. Your static compression would have to be outrageous to have a dynamic 10 to 1 and the camshaft would have to be tiny, as in 210s at .050 along with the 15 to 1 static. Look at the cam spec part of the equation again as I thing you entered the numbers at the wrong duration value.

Black LS-14

iTrader: (1)

I may have figured it wrong, but im not sure where its wrong. I know that it has to be okay because there are too many people running similar setups. My rods are 6.125" long. The chamber size stock was 64cc, so im figuring with .005" milled they are somewhere in the 63cc area. The head gaskets are .051" thk with a 4.100" bore. Is there anything else im leaving out?

jegten

iTrader: (22)

with the 4.085" bore from OP, scr 11.05 to 1, dcr 8.15 to 1
with the 4.100" bore from LP, scr 11.12 to 1, dcr 8.20 to 1

this is not taking into consideration the head gasket bore diameter and with the piston .007" out of the hole, but i think it is pretty close.