AFR/VE/Timing tables for 5.3 LS vortec engines.

bix

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2007 5.3L LY5, 218/227( have to go check the sticker on my toolbox to be sure) @.50 523/524 lift Stage 2 summit cam with trickflow .600 lift springs IIRC. Not horribly specific but just laying out the engine specs as to it being a mild motor with a freshen up.

When i uploaded the base tune for the ls in the terminator x max it fired up, it runs and all seemed good but after doing research into some guys like joes garage/sloppy mechanics and a few others on youtube who dyno test as a job, go over making tables for the LS and im thinking ive got some tweaks to do.. The youtube guys seems to know what they are talking about but when it comes to throwing timing at an engine up high and target AFR's but i dont want to damage my engine, obviously chances of that rise with timing advance and leaning out fuel for power, but im not trying to squeeze out 15 hp to kill an engine... but 17 miight be worth it.. :whistle:

If anyone on here can input or point me in the right direction thatd be cool. I know theres others on here about to do the holley terminator x too. Theres lots of info on other forums but i give ck5 all my forum time and have never found bad information here.



Few things ive picked up so are seem to be:

Set the AFR first and get it to idle close using the preset fuel base map and learning features if needed.

Then Advance timing at idle from 16-18* upwards to find the highest MAP while getting the lowest idle. From some information i found it suggests for medium cams , try within the range of 18-22 degrees of advance for a steady idle.

This is the AFR table i made with no revisions yet with the truck running but just based on info i had collected. 14.7 is Stoich but the .7 isnt as important apparently..:dunno:. A few guys i listened to said that with cam swaps sometimes they will idle best at 12-13:1 so dont be afraid to go that rich at idle if need be, so i figured id go rich and lean it outwhere its needed. The reason im motivated in this is the truck idles, but not great and i can definitely tune a less a loopy idle. WOT is apparently good at 12 and the power gains leaner arent worth the risk. Hoping to get out and load this on and see how it idles. i just auto filled the rows and colums to blend them for as rough starting point.


PXL_20210424_002814871.jpg
 
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Bent77

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@folkenheath was talking about this just yesterday

The 14.7 is the target number, but with dynamic conditions while running, those numbers definitely change

Now these numbers are on more traditional engines. Some of them are cammed with aluminum heads. But the AFRs will at least get you some ideas in lieu of a full table

 

bix

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I was reading into those pro flo threads last night, just wasnt sure if i should post up in there or not with my table questions and fuel maps. Learning lots though and they are basically the same system just dressed differently.
 

Bent77

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Quite a bit in common while still being different enough. Be nice if the proflo guys and terminator guys each understands the other enough to help each other tune. These seem to be the two most popular platforms at the moment
 
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bix

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For sure, the basics apply to anyone tuning a basic efi system but like you said we can all learn from eachother. hell.. 75% of what i know about chevys has come from this site one way or another.

ill try and participate in both depending on the information to provide, keep the standard EFI stuff on there and terminator specific stuff on here. Ill have to learn more about the pro flo system to understand what its similarities and differences from my system are.
 

folkenheath

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The LS engines like to be lean, I would set it more like 13.2-13.4 at WOT to make good power. Now if you have a dyno you can test different A/F ratios, and watch your plugs to make sure its running good and safe.

As for timing, I would set it for 28 at WOT to be relatively safe while still making good power, if you want to push it you could go 30 or even 32 but really be careful doing that. I've seen racing LS engines want 33, but those were aftermarket heads and pushing 8-9K RPM. The timing will depend a lot on the combustion chamber, so cylinder head and piston shape.

You are on the right track to set the idle timing and fueling by engine vacuum. Just make sure you watch the RPM to keep it the same, you may have to reset the butterflies and reteach the TPS. If you go too far on idle timing the engine may "diesel" on shutdown.

The cruise timing can be considerably more, around 40 or so, you can play with that to see what gives you the best mileage and performance.
 
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Bent77

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Why is it that these engines like to be a bit leaner?
 

folkenheath

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I'm not entirely sure, I believe it has to to with the efficient combustion chamber and higher ring lands than a typical BBC or SBC, they are effectively a little more efficient at using the fuel.

You can get that same stuff for traditional SBC and BBC with aftermarket race heads and pistons, like spread port BBC and SBC heads, then they like to be leaner too. A SBC is 23 degree, a BBC is splayed at 24 or 26 for the most part. But you can get heads in between for performance, 20 degree, 18 degree, 15 degree, etc. A spread port 11 degree BBC head has a chamber volume as small as 56 cc with those valve angles.

A traditional LS1/2/3 has 15 degree valve angles, an LS7 has 12 degree from the factory. Although some aftermarket heads use the 12 degree valve angle of the LS7 on an LS3 intake and valvetrain, they work quite well.

I should state not every engine is the same, maybe his LS will like 12.8, or maybe his 02 sensor is not measuring the same.

That's why I always say to look at the spark plugs, they tell the true story every time.
 

bix

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Thanks @folkenheath , im starting to nerd out in this area and its all new to me so thanks for providing some information. Ill definitely take note on some of those parameters. Ill bump up the WOT AFR to about 13.2 and go from there.

As for the timing at WOT thanks for that, ive seen quite a bit of mixed reviews so i definitely wanted to get some information from the guys on here. I definitely want to air on the side of caution but not "granny grocery getter" safe lol. The stock base tune had 36 total for cruising, which seems like a good ball park.

I went out to fire up the truck and plug some values in to try and smooth out the idle.. turns out i have a draw to find since my battery went flat in a few days of sitting.
 

Bent77

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@folkenheath

Are you finding that each degree of knock retard drops 1-3 hp?
 

folkenheath

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I don't use the knock retard to be honest. I want control of the timing. I can't say I recommend that, I'm just saying that's what I do. On a street engine with some boost, then I might turn it back on.

As for how many HP per degree, it varies a lot, and its way worse if you are further off.

In one example, moving between 24 and 28 picked up 16 HP, so more like 4 HP per degree there, and moving between 28 and 30 picked up about 4 HP, so around 2HP per degree, above 30 it picked up in a small window, and lost everywhere else, so it averaged out zero gain or a loss basically. Now this was a ~540 HP pull, so it will likely be less on a 300-400 HP motor.

So depending on where your timing is and how much you take out, it could be from 0 and 10 HP/degree(or more). Does that narrow it down enough? :D

High HP race motors on spray or boost cab be killing hundreds of HP with timing pull.
 

Bent77

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More reflective of reasonably stock stuff. I was reading through some tuning information and that number came up. Seemed like it was on point with what @bix was asking
 

folkenheath

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That was my quick answer because I just happened to check this place after putting some pork chops on the grill.

I think if someone wants to run the knock retard on a stockish engine in case they get some bad gas or something, I would worry about the engine more than the HP lost during the knock retard? It's not like they are going to lose an expensive race if they pull too much out in that situation. I might purposely make it so it is obvious that it is happening, so you feel it? What do you guys think?
 
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Bent77

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Yeah I think engine longevity is more of a concern. And if you know you’re racing, better not be using crap gas anyway

I’ll probably be doing some tuning myself here after awhile. Lots to learn
 
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folkenheath

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I agree, in racing we pull it out for traction control, not knock.
 
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bix

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Thanks for the info! Yea i mean im by no means racing this truck for anything serious if it ever happens.. :whistle: . Id rather it last, and although the top end is somewhat new, the bottom end still has 140k miles on it and i didnt swap out cam bearings ect.. Id like to enjoy it before it blows up hah.

Ill definitely play around with those number once its rolling and come back with the results.

Is the stock 36 degree timing for cruise right about where it should be in your opinion. As for the knock retard. I inputed the two knock sensors into the holley efi system but it then started asking me about frequency settings and im not entirely sure how to adjust and set that/havent had time to research so for now i have it disabled. i havent gone in to look at specific knock retard in the timing section either yet but id assume it wouldnt hurt to run it with a pump gas summertime cruiser?
 

folkenheath

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The only thing it would potentially hurt is HP when it turns on, it can only help the engine longevity. It's on there from the factory for exactly that reason, mainly bad gas, or some strange weather/pressure scenario that causes it to knock, so they pull out timing so the engine can last longer.
 
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