My first passes with the truck was with a small cam and some hand ported 4.8 heads. I went 13.60s at 96 mph, on the bottle I went 12:12 at 112 mph. Now I have a ms4 cam and the stage2.5 5.3 heads from texas-speed I tonight I ran a 13:71 at 98 mph on the bottle I went 12:10 at 108 mph. Here is the kicker though I had a 1.89 60ft on the bottle the first time I ran it. I had a 1.76 60ft this time what is going on?

 

well, that sucks that there isn't a big diff in times. Some one will chime in with the answer but, Good runs with that 5.3 none the less

 

sounds like your torque has gone up with the cam and the heads which will allow you to get off the line and through the 60 ft. mark faster. the loss in speed in the quarter means that your horsepower has gone down. the rpm your shifting at may have something to do with it. if your revving it to high, then the cam and heads might be out of their powerband. also, since your converter probably allows for a low drop in rpm between shifts, if you rev it too high then your just wasting time. shift at the lowest rpm possible where the next gear starts in your engines powerband. there is no way to know for sure, but it def. doesnt sound like your getting the full potential. only way to be sure is to have the truck dyno'd and see what your power/torque curves look like and tune accordingly. hope this helps.

 

I think I may ge running out of fuel on the top end is why the loss in mph,the reason I say that is because about the thousand ft mark it started to fall on its face,my check light started to flashing.

 

how much gas did you have in the tank

 

-Tune?
Small crap like
-plugs?
-wires?
-fuel filter?
-oil/filter?
-Weather?
-Bottle pressure?

Sounds like you ran out of juice up top and went real rich.

 

I had a similar problem when i first tried a 100 shot on a stock tune. my dyno tuner fixed it when he tuned it. he said it was the KR that was shutting me down and pulling timing and it threw a check engine light just like yours did. however, with the heads and cam, bigger injectors couldnt hurt. i've heard that the injectors from the 8.1 fit right in and flow more fuel. if this is true, that should be an easy way to go.