Predator

I'm just beginning to explore the world of aftermarket heads, so please forgive my naivety. I've been trying to find out at what CR you have to start pulling timing? Specifically, the 10.5 CR LS6 heads. Can you run 28 or 29 degrees of timing at that CR?

Viper

iTrader: (6)

I don't think you'll know till it's on the dyno and you see what the car likes.

Predator

Thanks Viper, I see, there's no general rule-of-thumb that cars with CRs of 11:1, for example, or 11.5:1, or whatever usually need to have timing pulled? I was thinking that 10.5 is pretty close to stock and you could run with full timing. The truth is that I want to get a set of LS6 heads but I don't want to mess with my timing curve.

Viper

iTrader: (6)

Depends on what gas is available to you as well. I'm running 11:1 on 93 octane with zero KR. Full timing.

Predator

93 Octane. If you're running full timing with 11:1 and 93 octane, I think you just answered my question: full timing is feasible with 10.5:1. Great news to me, and I appreciate your help!

Predator

BTW Viper, your avatar has your car flying around cones, and my car is parked (lost) in the woods, like me. LOL

SideStep

You can run 27-28 degrees of advance at 11 to 1 compression... I am and several here on the forum are doing it with even higher static compression. Don't worry so much about static and concentrate on your DCR. Many threads here on the subject, basically shoot for a DCR of 8.4 - 8.5 on 93 octane gas...

If you are worried about the LS6 heads, don't be. What cam, head-gasket are you running???

DramaFoYoMama

I've never seen an LS6 head make power past 22*.

Predator

Thanks SS, cam in sig, stock heads at the moment, but big plans for the spring.

Predator

Does that contradict what's been said??

SideStep

If all else stays the same and all you do is bolt on the LS6 heads your DCR is only going to change (increase) approximately .22 and you still be under 8.4 DCR. Go ahead and do it. The REAL answer (as to how much timing you can run) will be in scanning for KR while you are dynoing. Find out what gives you the most HP, then see (scan for KR) on the street if you can use the same timing values. If not back it down a little...

Good Luck,

Predator

Thanks again SS, that sounds like a solid plan!

DramaFoYoMama

Is that an actual question, or are you just attempting to be a smartass? Everyone is telling you to run 27-28*, but what's the point on LS6 heads? Even if it doesn't knock, I seriously doubt it will make any extra power.

Predator

No, a legitimate question. As you said, everyone was saying 27-28* and you said no power to be had over 22. I'm not talking about stock LS6 heads, but something like Patriot's 243 casting Stage II heads. Should be good for 30-40 hp. No offense, but I don't get the point of your posts.

calongo_SS

iTrader: (7)

Read this:
https://ls1tech.com/forums/advanced-engineering-tech/254868-ignition-timing-101-a.html

Very good information in the 1st page. Keep in mind that every car is going to be different, no one can really say for sure "you can run a 29 deg of timing and be ok for sure". Especially with a head with a welded CC, diffences in the CC are going to make a differnece in the combustion process. I would wait to do the heads until you can retune. Or just go ahead and slap it together and hope for the best.

DramaFoYoMama

I apologize if I came off as being rude. I saw the extra question mark and thought that maybe you thought I didn't know what I was talking about. Basically, the more efficient a head is, the less spark advance it needs to make power. Like already stated, I wouldn't put LS6 heads on an F-body with an LS1 tune as it's asking for trouble IMO. It will knock like crazy and possibly ruin the motor if it goes lean. Lean and extra spark = Just remember that more isn't always better.

Predator

Appreciate the link, that'll keep me busy for awhile.

I can retune at any time, I was just hoping I wouldn't have to mess with my timing table, just fueling changes. Truth is I haven't figured out the best way to tune my timing table. Sounds like I have to learn, or wait on heads until I know what I'm doing with timing. The only changes to my timing table are for idle, and I hired a tuner to do that. I'm comfortable doing fueling changes, and I have an LM-1 to assist me. That's why I was wondering (hoping) that I could do heads and just worry about fueling, but maybe I'm in over my head. I know the Patriot 243 heads I mentioned would probably have a compression ratio of 10.5:1, hence my original question (post). I'm trying to learn more about cylinder heads and tuning for them, but I have a long way to go. Thanks.

DramaFoYoMama

Why don't you copy and paste the timing table from a Z06 as they have the 243 heads? It will give you a place to start at. You can add in the idle timing that you did to the table. There is more than one recommendation around here on how to tune the timing table. I would say tune it to how you like to drive the car.

Predator

No problem dude, my post to calongo should explain a little better where I'm coming from. I'm trying to learn, and it sounds like heads are something I probably shouldn't try to tackle until I have more tuning knowledge. I like doing stuff myself, and I only hired a tuner to help me sort out my idle because I didn't have much luck myself. To sum up, it seems I should learn about timing tuning and wait on heads, or get the heads and hire someone (which I don't really want to do). Thanks.

Predator

That's a great idea. I might be able to tackle that.

I think you get my point that I was hoping I could slap on a set of heads and just tune fueling (because of my lack of knowledge). Sorry about the misunderstanding, but I never thought you didn't know what you were talking about, I'm the one who's challenged here. Thanks.