Honk3X

So ive recently started doing my own tuning over the past month and have learned a lot. Definitely glad I have done so rather than relying on other people.

My Mods are-
LS2 stock bottom end
LS7 cam, Ls3 springs, hardened pushrods
PRC LS3 Heads milled .030 (about 66CC)
Full C6Z exhaust
Ls3 intake
Vararam

My car was professionally tuned and made 430/401 on a dyno jet in march. At the time my tune had about 23-24 degrees and about a 12.5 AFR.

So here is the issue-

Its much hotter here in Utah then it was when I was originally tuned and im thinking that dyno vs street isnt very accurate because of my vararam.

At WOT I was getting up to 5 degrees of knock in some places! At the advice of several on hp tuners and also local pro's I was advised to desensitize the knock sensors a little and add fuel (I was told Ls3 heads like lots of fuel. Even after doing that, I had to pull 1 degree out everywhere. Now I have about 24 degrees down low, 22 around peak torque, 23 from about 5600rpm on up. Before it was a mostly solid 24 degrees. I also had to richen it up to a 12.3 or so. all of my tuning was done in 4th gear. The only thing I can think of is heat and the much larger amount of air going through the intake on the street when compared to the dyno. Does this sound normal and reasonable?

What are you guys seeing for timing on your LS3 or LS3 Heads?
What AFR have you had best results at?

Im just trying to compare my tune to current setups.
My c5 had 29 degrees of timing so I was surprised to see such a big difference.

Ive have done 3 solid days of tuning trying to get as much timing back in, in comparison to my original tune and close to the same AFR. It just wont take any more timing or any less fuel.

What do you guys think??

schpenxel

It doesn't really matter what other people are seeing--if that's what yours likes, then that's what it likes.

The more efficient heads are the less timing you'll want/need. Old SBC heads ran mid to high 30's

More timing is not always better.. you'll make the most power with peak cylinder pressure occuring at around 15* ATDC. Anything later OR EARLIER than that isn't doing anything to help you power wise.

Fortunately for gasoline it's common to get knock just after advancing timing too far.. so once you dial it back a little you're usually pretty close. Not true for some other fuels.

TurboLX

Find new people to get advice from.

You raised compression, so you should EXPECT to run less timing in many places, including WOT. The increased compression speeds up the combustion process. You no longer NEED as much timing, and you are also more likely to get knock sooner on pump gas.

If you're already running lambda=0.85 in NA form and you're getting knock, chances are VERY good that you just need to reduce the timing (most likely in the high octane spark table). Sometimes less is more...

z06scentair

Compression was raised?

I'm not seeing that.....

LS2 243 CC = 64cc

His LS3 milled to 66cc would indicate a drop in compression by .4:1.

The camshaft VE's are the primary driver for less timing demand. Agreeing that sometimes less is more.

Willy_peckham

hi i have pretty much the same set up but with a turbo and wondering what ur running for timing and how ur set up is doing

hubes

Hi *****, welcome to the forum. A turbo engine will have very different requirements than an NA engine, both fueling and timing. Also this is a 5 year old thread, you'd be better off starting a new thread with any questions you may have. You'll find the people on this forum quite helpful, but there doesn't seem to be a whole lot of activity in the scan/tune section. You might find more help on LS1tech or the hp tuners forum

phils C5 vette

If your vehicle has over 50000 miles, you probably have a good amount of oil pooling in your intake manifold. So your fast moving air over your intake manifold is picking up oil partials which is going to mix with your 93 octane. That will bring your octane level down.

Spray two separate applications of Seafoam through your throttle body to soak it up and blow it out.

2nd, dont make all your WOT one timing setting. I call that lazy block tuning. The tuner put 25 degrees from 2800 to 6000 RPM down to 62 G/cyl to 1.20 G/cyl. I like to make a V in my timing table and remove the extra advance before it comes on. So lets stay knock comes on pretty common at 4400-4800 RPMS so take out 2 degrees at 4200 and 4600 RPMs and if it come on at 6000 RPM again, take the timing out at 5800RPMs this was you keep the extra advance.

Ill explain my V in the WOT area. from 2600 to 3400 RPMs lets say you have all that area 25 degrees from 62 to 1.20 G/cyl. then in the 4400-4800 RPM range you want to drop the timing in that area a 3-4 degrees from the .62 to1.20 G/cyl after that range you want to build it back up from 5000 to 6200 RPMs and add back in a couple degrees. Then if its still knocking, again go cell by cell and remove it.

I see to many lazy tuner just enter 25 in all the WOT cells and call it a day.

Its truely and art picture to look at and say that makes sense.

schpenxel

I've seen one that was all one timing value for over half the table. Like, yeah people, it totally makes sense that it works out to the exact same ignition timing despite drastically different airflow and RPM's depending on where you're at in the table. Rrrrright.

phils C5 vette

I think the shop that does it around me in St. Petersburg figures What the heck, the car makes enough power with the new modifications. No sense in optimizing it like you paid for.