chevyracer8262 wrote:10.4:1 comp
powerband from 1500-5500rpms
93 GMC ext cab 4x4 with 33" tires and 3.73:1 gears with a modeified 4l60e tranny
chevyracer8262 wrote:What grind cam do you think would do best with that fuel and comp? I'm trying to lower the comp as much as I can with thicker head gaskets and laying back the chamber as much as i can.
chevyracer8262 wrote:Ok since I got these replies I've been rethinking my combo, I have to use the rotating assy that I've bought, can't afford not too. so i'm run some math and please correct me if I'm wrong this is the first engine I've ever put this much research, planning and math into. I've been reading about static ans dynamic comp ratios and came across some info of past engines that GM built that ran high comp ratios and still was able to run off of pump gas. The one that hit me was the 11:1 comp 375hp 350 lt1. Now here's the calculations I came up with, using a compression calc I found on the KB-Silvolite website. Using the 4.030" bore block, 64cc heads, 4.125 bore .039"thk head gasket, 0 piston to deck height, 3.75" stroke and 5.7"lg rods It calculated a static comp ratio of 11.113:1 and using the specs from an old school L79 cam advanced 4degs it calculated a dynamic comp ratio of 7.559:1. I've read several articles and posts stating that an engine running on 91 octane of greater needs a 7.5-8.5:1 dynamic comp ratio to run safely without any detonation issues. Now would this engine at these specs with that cam run dependably and strong with that cam and a 2000rpm stall converter? I'm really looking for dependability because this engine is going into my truck i had other plans for different heads and cam combo when I bought the rotating assy but financial reasons have made me have to change direction, and the engine in my truck is shot so I can't wait till I can afford the other parts. My buddy gave me these 186 heads and the new L79 repro cam, so if I can use them that'll be great, I also have a set of 1.6:1 roller rockers to give the cam a little more lift.