So im working on tuning my 03 Silverado, LQ4, ls9 gaskets, LS3 heads, arp bolts, LSA blower and drive accessories, stock pulley set up, LT headers and stage 1 texas speed cam. right now its runnign about 8psi, i have timing set at 13 degrees and im getting about 1 to rarely 2 degrees of knock, fueling is on point at the 11.8-12.0 while in boost, running TR6 plugs. in the past before i replaced engine mounts which were a huge issue, i had it at 18degrees timing no knock but only in 2nd gear (as engine would torque to much and hit frame and etc and give false knock with stock mounts when i did a 1st gear pull), it would fly at 18degrees timing highway pull in 2nd gear no knock, now that i got solid mounts on it i don't have any false knock from engine moving, i want to bump it back to 18 degrees now that i got fueling dialed in basically but getting 1-2 degrees knock only at 13 has me a little concerned but truck also feels under powered. what would you all say is normal timing amount for an lq4 with an lsa? should i be able to get more then 12-13 degrees out of it?

i also have a lq4 with turbo cam in my race car and a t76 turbo, 317 heads, was running 13psi and had it at 12 degrees timing and no issues which is also why i feel i should be able to put more timing in it since its only at 7-8psi and not 12-13psi. curious to know if heads could make that difference or not.

maybe some one has a little insight on something im missing. i am still dialing in the tune but i dont want to spend to much time chasing my tail on this timing issue if its not an issue.

Thanks!

 

That AFR is leaner than I would like to see it and you could likely get a couple more degrees of timing if it were fatter assuming 93 octane. Was the cam degree'd? You're saying you only swapped motor mounts and your knock threshold dropped by 5*'s? Sounds like something else changed. What do the plugs look like?

 

At 8psi it might like 19-22* on pump gas with that setup. If you have solid mounts you will prob never get the knock sensors calibrated well enough to ever use.

 

you think i should be aiming more towards 11.6 AFR? and i put new plugs in it also when i did the engine mounts, TR6s gaped at .024. i am running 93 oct. cam was set up mark to mark, or zero'ed i guess. didn't advance or retard it based on timing marks.

to get more detailed on the timing and engine mount thing. i could audibly hear it rattling/hitting the frame/steering shaft and feel it in the steering wheel (coudlnt steer the truck under throttle it was so bad lol) . if the truck shifted gears or down shifted or any change in "torque" id see 5-8 degrees of knock, even if i wasn't really getting on it. If i was to slowly roll into it in 2nd gear on the highway were it wouldn't violently twisted the engine up and cause it to hit something because of a down shift or just the quick response of 1st gear, i didn't get any knock and did consistent smooth pulls at 18 degrees advance in boost, and situation was repeatable with same out come, high way 2nd gear never knocked, would get 7-8 degrees across the board any time i got on it and it down shifted or shifted into 2nd or romped on it from dead stop.

and yeah i would of thought id be in the 18-20* timing area on only 8psi and 93 oct but wasn't sure.

This is the cam shaft im running.
LS3 stage 1 supercharged cam by Texas Speed
Cam Specs: 223/231, .629"/.629", 115 LSA, 112 ICL

 

It would be interesting to see if you run it a little richer, like 11.4, if you could put more timing back in. I also usually run nonprojected TR7's on anything boosted, some complain of driveabliity issues, but I haven't experienced that. I still don't understand how changing motor mounts and plugs means you lost 5* of advance unless you have a fueling issue and your wideband is fooling you. I think I already asked, what do all 8 plugs look like?

 

ok i think i miss typed it a little, my original tune i had it commanded 18 degrees timing, when i started logging i was getting the 7-8* knock under any throttle, thinking it was real knock i went back into the tune and changed my timing under boost from 18* to 13* commanded timing to try to get a better base line for getting the tune dialed in and not blowing up. After i changed to commanded 13* timing i still got 7-8* knock like when i commanded 18* and after a while of diagnosing i realized it was from bad engine mounts and the engine twisting up and hitting frame and steering shaft, so i was probably fine at commanded 18 degrees timing if my engine was not hitting the frame and steering shaft. After that i put in solid engine mounts but left my timing at commanded 13* , i did a log to make sure that fixed the knock issues and it did, but here and there i would still get 1-2* maybe 1 out of 5 pulls, because of that i did not want to command 18* timing again with out seeing if i had some skewed view of what the timing should be and get others input in case i was trying to achieve an unreal timing number.

also i have way more time to be on here and type and ask then to mess with truck atm so if this saves me from trying another 5 tunes to figure it out i thought it was worth the ask here.

plugs looked kinda eh, white and ashy on some but they were also the same ones i had in it when i had a big fueling issues of going lean so i didn't trust them and why i had an extra set ready to swap out when i finally got around to doing all this, i need to pull the ones in there to get a real view on them, if i have time today i will.

there has not been a ton of true tuning done yet, i dont have a lot of time to work on this vehicle so its usally a log or test on something here and there not a steady diagnos, tune retry like i should be tbh.

i was looking into running TR7s or at least in my racecar since thats putting out a lot more power/boost, glad to hear you dont have any idle issues

 

to me it sounds like you've ALWAYS had an issue at 18*, just some of it was real knock and some of it was false. You should be reading the plugs to see if there is any speckling on the porcelain and where the timing mark is on the ground strap. Those are both indicators as to where the timing should be.

 

and i would agree with always having an issue at 18*, more so from bad mounts but also timing. From what i was reading is that a lot of LSA cars, ether actual LSA blocks or not are all like 24* or more, which is why i thought it was weird for me to see any knock at 13*

i havnt really read plugs before so thats new to me and im learning, i know what a good one, bad one, lean one looks like but not great at identifying problems based on the plugs

 

I don't see how LSA cars running 93 octane can be running 24* of timing since that's basically stock NA timing. People on here seem to say puling 1* of timing per PSI is a safe rule of thumb. If 24* is stock you would be in the 16* range at 8 psi....which would also happen to correlate with 18*-(1 or 2 degrees subtracted from knock)=~16*

 

I'd set the EQ ratio to 1.28 (11.5:1 A/F on straight 93) and then creep it up 1 degree at a time checking the plugs.

 

thats why it was not making sense to me, and yeah when i was running 8psi in my WS6 i was around 17* i think.

yeah thats what i was going start doing today, check tune, change some things a creep it up a degree after peeking at plugs and see where that puts me.

 

Where are the knock sensors?in the valley? Or did you put them on the side of the block? You need to stop **** from rattling around. I had a lot of false knock when I first built mine, until I just kept chasing it down.

 

there under the valley, stock lq4 03 iron block, and yeah thats what i traced down when i did mounts, redid exhaust and checked everything while it was apart.

 

Stock LSA cars do run very high timing because the engine is designed to be supercharged. Piston oil squirters, piston design, compression and camshaft all play a huge part in this. In stock form they run 22-24 degrees when the temps are low enough .

 

So until about 3500 rpms

 

I have a similar set up to yours ls2, ls3 heads lsa with stock pulley(8psi) I was commanding 19* with a afr of 11.5. I now have a 2.40 upper (13psi) stock lower and am commanding 14 degrees on 93 at 11.6 afr. I don't use my knock sensors though because I have damn near solid motor mounts so I get a bunch of false knock.

 

I think your plugs are too tight to be honest. I'd set them at .032 and start there. I'd go to a 7 plug as well since you've already cammed the car. TR7IX's are what I run (as well as most of the V (LSA) crowd.
I tried the BR7EF's and my car just didn't like them.

What's your compression at? I'm guessing stock upper pulley?

 

^How would too tight of a plug gap induce knock?

 

I'm not saying it would. It's just something that stood out to me in the post, that's all.

 

I have a ly6 with a Whipple 2.9. I'm running 18* @ 14lbs on 93/water/meth but my car still has vvt.( mast vvt cam) it seems to run best with the tr7ix also. Now I'm not implying you go out and run 18*, but if you add meth or 50/50 you will be able to run a few more degrees with much less knock. How are your intake temps?