Tri5Nerd

iTrader: (3)

With the type of gas we have here, is it a good idea to run that compression in a stock bottom end with CNC ported heads and Torquer v2 cam?

12secSS

iTrader: (30)

That shouldn't be a problem, so long as the timing table is adjusted to compensate for the higher CR.

travie319

iTrader: (1)

Ryne @ CMS

iTrader: (10)

my old heads cam motor had around 11.2:1 compression and ran fine on 91 octane, proper timing table and a/f ratio, should be fine

WILWAXU

iTrader: (6)

My car was setup to run on 93 "east coast" gas. I've had to run a shot of octane booster in each tank of gas to keep it from pinging.

I'm sure it could be tuned around it, but I'm not planning to be out here much longer (besides I don't mind running good gas for the track )

Ed Blown Vert

iTrader: (2)

Yep did it also on my old engine.

Tri5Nerd

iTrader: (3)

I was told from 26* to 28* timing would be in the ballpark for that compression ratio. Is this correct?

Ryne @ CMS

iTrader: (10)

i had 28 in mine it ran fine

Bombguy99z28

I run 21* timing, 11.8:1 static compression, ~9.0:1 dynamic compression, ~95 octane.

Lots of good threads in the tech section about timing.

strokedls1

iTrader: (1)

I run 91 with 28.5 degrees with 11.2 static 8.0 dynamic compression. I used to be around 11.8 and had problems. Most of it is in the tune though.

Bombguy99z28

Its all about the dynamic compression. As long as you keep it under 8.5 you should be able to run 91 octane fine, at least from what I've read. Timing is really dependant on your setup and heads. LS6 heads you prolly wouldn't want to run that much timing, worse heads or larger displacement yeah, you prolly would want to run that high.

Rick@Synergy

iTrader: (5)

We have a car that runs 12:1 CPR on 91 octane, and another one that we are doing that will be 12.5:1+ on 91 also. Its possible.

Rick

Bombguy99z28

What DCR?

Race-Prep

Yes, with the right cam you can go pretty high with the compression, but I would shy away from anything higher than high 11's to 12.0 as the cranking compression gets too high and you end up with pinging issues and you need to neuter the timing back too much. Remember you have to use a good sized cam to get away with this, or you will be taking your engine apart I assure you! I honestly think you need not run that much if you have a really good set of heads and intake on the engine as this will increase your dynamic compression, which makes much more power than static on pump gas.

-Bryan

Tri5Nerd

iTrader: (3)

When you say a good size cam are you talking about cams with bigger duration and lift than the Torquer 2?
I'm just looking for somewhere close to 11 to 1 compression using said cam and some 241 CNCed head with 2.04 and 1.57 valves, these heads are unmilled which would give me about 10 t 1 compression if I use a standard MLS gasket. But if I mill then let's say .030" and use a .040" Cometic gasket and a .037" quench then that would get me close to the desired compression, what would my Dynamic compression be?

NICKZ28

Just mill .030 off 5.3L heads and use stock thickness head gaskets. You'll be right there.

Tri5Nerd

iTrader: (3)

I have 5.7L heads (241 casting), not 5.3L would that make a difference?

NICKZ28

They have a smaller combustion chamber to start off with. Meaning a little more compression.

Rick@Synergy

iTrader: (5)

I will have to run the math on the camshaft again, I dont know off the top of my head right now.

Rick