Shifting at 6250, mph was 88

 

Might want to get a wideband and see what your AFR is doing. Then get you some tuning software and see what's in the computer.

 

My bone stock 2000 RCSB 5.3L 4L60E 3.73 with heavier than stock 18" billet wheels ran 15.60 @ 87.6 MPH. I was told that it was slow, but 16.2 with mods is horrible. I would have thought more around 14.3 - 14.5 with that setup. I'd trust a mail order tune on a spare PCM over what you have now.

 

What does the truck weigh with you in it?

It does seem slow for what you've done, I would not rely on Dragy, I use professional instrumentation, VC200 or VC2000 or do to your local drag strip and make some runs. You can learn a lot from a time slip.

 

The draggy's are extremely accurate. Ive tested a few of them on turbo cars and its amazing how accurate they are compared to the time slips at the track. And this is from cars running 4.1x to 6.5x in the 1/8th.

 

Ran a log on it this weekend, injector duty cycle was at 92% at 6000rpm.
Max timing was 20 deg, seems a bit weak to me. Think I'm gonna take the timing cover off and check cam timing.
Then go from there, truck should be running 14's all day.

 

My truck must have been made on a Wednesday then.
2000 ECSB 2wd 5.3 3.42s 275/60/16 tire and I was learning how to tune back then. It went 14.72s consistently. Could have gone 14.5s with a few little changes.

 

Yea 20* is low. Even for 87 octane.
read the tune off and post it up.

 

Key word TUNE. Did your truck go 14.7 on a completely stock tune? I know my father's 2000 Sierra was way faster from stock tune on 87 to a street tune on 93. It went from 15.7 to 14.8 with just a tune and better fuel.

 

Yeah, 20 degrees doesn't seem like nearly enough unless you're still running 87 octane. (Even then, still low) I'm running 26.5 total on my LQ4 with 862 heads. I with think a lower compression 5.3L 28-29 would be more in line.