LQ9/LS2 Tuning Advice - Ignition Advance etc.

[flak monkey]

Just got my LQ9 based motor running yesterday - spent most of today chasing a few issues here and there, but I think I at least have it idling OK now when it's hot. I had to turn on closed loop idle to get it to idle in gear - otherwise it had to run at about 1500rpm to stop it stalling when you put it in D.

I just tuned idle to give the best vacuum, still not great, about 75kPa in gear. About 65 in neutral, but given the cam and motor spec that will have to do. Seems happy idling around 14.2AFR and 27deg advance.

Does anyone have any idea what the total timing figures normally are on LS based motors? I know it varies depending on spec. However most people used to say 34-36 on a SBC. What's the figures for an LS, I searched, and couldn't find the answer. I just want a safe starting point that's neither too advanced or too retarded.

Just as a word of advice - the 'Idle Up' setting from Megashift to MS3 doesn't seem to work - I am using closed loop idle anyway so it doesn't matter, but there seems to be something wrong there somewhere.

I need to check my transmission controller is working properly - couple of issues there I think - and then change out my oil before taking it for a drive and see what happens....

https://www.youtube.com/watch?v=-dWctterxKI

[coreymartin]

I just went thru similar question. I have a 5.3 up and running with 243 heads and ls6 cam. I got on ls1tech and got a couple of people ti post uo their stock timing tabels. The Z06 vette has a total stock timing of 22.5 degrees at wot. A 99 camaro SS had 28 deg total at wot. So there is some variations. But none of the ones I saw were above 30deg. From what I read, the cars with 243 heads don't require as much because of th much better design, flow, and quench of the head compared to a stock ls1 head

[coreymartin]

I have attached one of the examples that I used for reference. Stock off of a SS camaro

[5.3LS10]

I have a buddy with a 5.3, LS6 heads and LS2 camshaft with LS6 intake.

How big is the CAM?

That seems like a lot of intitial timing depending on the size of the Cam.

I have idle timing at 18* (makes about 22" of vacuum at 14.3:1 Fully Sequential) and WOT it makes best power on the dyno at 28*. It made like an additional 2hp at 29* but gained like 18hp from 27 to 28 so I run it at 28* to be safe. I will never notice that 2hp.

Seems like converter is too small or idle fuel/ign needs tweaking if you are noticing a huge drop like that.

Most fuel injected LS engines will make peak power below 30*.

Now carb setups requre a lot more. I am dynoing a 6.0, 799, victor jr, 23x/24x combo and it is making peak power around 34*.

[kaeman]

I have several buddies that are running big cams in boosted ls engines, all of them have less than 28 degrees advance in high power portion of the ve table, most of them are making 700 rwhp at 24 total advance. The ls engine doesn't require nearly as much timing as my sbc does.

[flak monkey]

Thanks guys, I have a few other issues to sort out right now. I do have it idling better than it was and I also found out the TCC was partially locked up, so I fitted a sonnax valve in the pump and that's really helped, it now idles in gear OK.

The cam is 236/242 @.050, .621/.612 lift

I'm interested in the idle advance figures, mines at 26deg at the moment, perhaps way too high? It's still idling at about 75KPa in gear and about 55KPa in park.

[flak monkey]

On a long drive yesterday I noticed I'm getting a bit of knock under light acceleration around 2000rpm. I rechecked my base timing and made a minor adjustment (retarded 2 deg).

I'm still getting a bit though. My spark table is below.

Cruising info:
30mph is 45KPa @30deg advance 1800rpm
50mph is 53KPa @30deg advance 1900rpm
60mph is 52KPa @32deg advance 2250rpm

Light acceleration is about 70kpa and 24/25deg in all cases.

The chart posted previously is useful but I'm not really sure how the mass air flow will translate into KPA, so perhaps I need to reduce my lower RPM advance some more.

I'm running around 11:1 compression with standard UK 95RON pump gas (equivalent to 91 Premium in the USA). Perhaps I should consider running on Super 99RON (93 equivalent in the USA)?