Scalpel

iTrader: (4)

SCR 11.72:1
Pump gas - 92 octane
Timing 27*

Phil'sC5vette

iTrader: (4)

11.7:1 on 92 oct.
OK im feeling much better now

2001CamaroGuy

iTrader: (6)

depends on how the engine is setup..........

on my 388 with EVERYTHING (piston crowns, chambers, valves, and ports) ceramic coated and using Evans coolant.....I "CAN" run 87octane with it's 11:1CR and 28degrees of advance......I will probubly go up to 12:1 or 12.5:1 when the LS7 style heads get really going (ie: easy to get)......

when I had a 11:2CR head/cam 346 (stock block), no coatings, and water(coolant), I HAD to run 91/100 or it would detonate like crazy with 26degrees of advance......

on my stock 5.3L silverado with it's 9:1CR and water(coolant) , I have to run 89 or better octane to keep from detonating with 24degrees of advance.........


the "safe bet" though is ~10.8-11:1 area.......

Phil'sC5vette

iTrader: (4)

I need more views from guys that have 346 ci

Phil'sC5vette

iTrader: (4)

ttt

jrp

iTrader: (16)

from what you've given i come up with 11.0627365673002 SCR and 8.64262363599881 DCR.

some good reading:

http://www.popularhotrodding.com/tec...power_squeeze/

racecar

I'm about 11.6 and have to add 1/3 race fuel to each tank to avoid a knock.

Phil'sC5vette

iTrader: (4)

You da bomb.
how do you think that will be on 91 oct, but I do have 93 here. But I was trying to set it up for 91 in case I was transferred to an area that didnt have 91

SStrokerAce

iTrader: (2)

Phil,

The real question here is how much cylinder pressure can pump gas handle... Compression (both static and dynamic) and VE are the two biggest factors to this.

Bret

SideStep

8.6 DCR on 91 Octane seems really steep...

eb02z06

iTrader: (18)

AFR 205's milled .040 for 59cc chamber and the .040 cometics equals around 11.6-11.8 depending how much the piston is out of the hole. Stock LS6 cam, 22 degress total and no knock on 94 octane. 405 rwhp through the manifolds and 420 through headers. Switching to a 222/224 .566/.568 112+2 cam soon-DCR will be 9.1 and we shall see what happens!

ArcticZ28

iTrader: (14)

Excellent excellent article. A lot of good points I never knew/thought about. I can't help but question the "get your water temp as cool as possible... 170-180 or less". I guess he is referring to typical small block chevy's of the older years rather than the LSx's. I thought optimal temp was around 180. Just wondering.

Also, I have a specific question to my setup. I'll be running 11:1 on my new HPE 408 with diamond flat top pistons with -2cc reliefs, a 244/248 .635/.627 112 +4 cam, stock 6.0 MLS head gaskets, and stock LQ9 heads. What would be my Dynamic CR? I still don't quite get that formula. I live in VA where it gets pretty hot AND humid in the summer, but in winter it gets damn cold as well. So, I'd need an average octane to run. Would 93 be ok for me? I can get 94 at sunoco if need be, but I'd like to have some room to run. Any help on this, I'd appreciate it. This is def a great thread.