I've been curious about this but never have gotten a for sure answer. I know every truck is different so it's hard to give a definate answer but im ok with a ballpark answer

Most "stock" vehicles today include CAI, and a muffler of some sort. My current truck is an 03 GMC 5.3L. It's stock except for a CAI, magnafow, e-fans, rebuilt trans. The current tune on here is horrid and all over the place.

My main question, How much timing can you run on a so called "stock" 5.3L?

I know my old H/C 5.3 would run about 27ish degrees of timing with no knock. Right now this truck only sees 17 at WOT and surely it has more than that being a stock truck and all.

Thanks in advance

 

17 deg... Thats it??? Id say you need to be around 25*. Best way to find out is make sure the fuel is correct then up the timing till you get KR then bring it down a few deg to be safe.

 

Mid to upper 20's depending on fuel and ethanol content. I ran up to 30 on my 4.8 with no KR, however it didn't pick up any et over 28

 

24*....

 

How much and where do you guys mess with timing when a guy adds longtube headers to an otherwise stock truck?

 

There definitely is no "for sure answer"...especially if there's no mention of even what octane gasoline you are running. My longtube'd, CAI'd, e-fan'd 2002 5.3 Silverado is very happy (and runs quite well) with 20ish at WOT...

BUT....

I am also tuned for 87 octane. I put 350+ miles per week on my truck, and my WOT vs. Cruise to work ratio weighs heavily towards the "doesn't make sense to run 93 octane to drive back and forth to work" side.

 

Thats kind of what i expected. I know every truck is different and there is no definate answer. I was thinking 22-25 should be what its at. I ran 93 on my old truck. I'll probably run 89 in this one. I would run 87 but im not sure of the tier grade of gasoline in Wichita Falls. I know back home in fort worth the majority of the stations have good gas. Its kind of hit/miss here though. I try to get it at shell most of the time.

 

Timing will need to vary depending on RPM at WOT. Timing will obviously be less at peak torque. Secondly, I think in general most people don't have an understanding of the fact that more timing does not equal more power. My stock internal LQ9 didn't like anything more than 24 degrees or so at peak torque (with 93 octane). There was a 500 rwhp LS2 dyno I was reading recently that achieved peak power with 22 degrees.

In general though, for a stock internal truck motor, 24-26 degrees sounds about right.

 

Lol. I recentlly started running 89 octane in my truck to see how it would do. 2 tanks later no issues at all, 27* of timing at WOT, zero ping and zero KR. Honestly i have noticed zero performance loss.

 

Peak timing is one thing but the amount of timing it had to go through to get there is another. My 99 even on the 02 operating system had absolutely horrible part throttle power and response. I only run 87 octane and this is what works pretty well for me. I was getting just a little bit of knock as the engine came up to peak torque at 4000 but after backing it down two degrees from 4000-4400 and smoothly bumping it to the max of 28 there was no more knock. Runs pretty hard for a basically stock 99 5.3 liter, stock air cleaner, just efans and a single 3 inch muffler in an otherwise stock exhaust system, 3.73s and 33 x 12.50s.