My truck has the stock 4.8 in it with a procharger ( about 13lbs of boost @ 5800 rpm). It used to be a 5 speed, but now has a 700r4 in it. I have a 2500 stall, 4.10 gears ( eaton), and 31" tires. The problem is that when at the track ( or street) if I floor it to take off, it leaves like a dog. However, it leaves better if I roll into it. I am running HPtuners 2-bar sd tune. Is there something I can "adjust" ( like a table or two) to try and regain the 60' times I had with the 5-speed ( 1.72's). My best 60' time as of last thursday is 2.100. Also, if I try to stall it up and launch, it's worse than just idling/ flooring it. I tried racing with my slicks ( 28" tall), but the 60 ft didn't improve. Any suggestions?

 

Have you tried adding more timing in the lower tables?

It sounds like you may have a difference in tables if WOT leaves softer than rolling into it.

 

Well, honestly, I chalked it up to the new "new combo" ( the 700r4). My cousin suggested it may be in the tune. That's why I figured I'd post. I'll have him look into it, though. It also ( and again I just chalked it up to the 700) falls on it's face in 3rd going through the traps. It's only picking up about 15 mph between the 1/8 and the 1/4. Do you think this is in the tune also? It has gone a best of 13.59 @ 100.4. ( on the 31" tall kuhmos).

 

It's a non lock-up tranny if that means anything in the scheme of things.

 

You need to log your timing and see where you're at when you launch. After that, you may need a bigger converter to see a 1.7 60' with that procharger.

 

The only problem with the bigger converter is that it's non lock-up. I am slightly relieved that both you guys think it might be a timing problem, though. I'm open to any suggestions. I have a forged bottom end 6.0 with stage 3 6.0 heads ( 2.08/1.60's) ready and waiting to go in, but i'd like to get the stock 4.8 dialed in before the swap. On that note, the 2500 stall converter that's in it should see a little more stall with a torquier ( 6.0) engine and I still need to keep this thing as streetable as possible. I doubt it'll see 1.7x 60' times again with the 4.8 and the automatic, but it's gotta get better than the 2.1xx's it's doing now.


p.s. with the 5 speed, the best it ran was 13.78 @ 102. Do you think the "tune" could be the problem with the loss of MPH?

 

If you don't have ALL the torque management removed, your timing will drop to negative numbers when you floor it from a stop. That will hurt your 60' bad.

I don't blame you about not wanting to go with a bigger stall with no lockup. Why did you go with the 700 instead of the 4l60?

With forced induction, your tune is everything. You should be around 11.5-1 air/fuel ratio, and have your timing set at 15 degrees or more for the WHOLE WOT run to run pretty strong with your setup. Do you know where your timing's at right now?

How about your IAT's? When I had the ATI 2-core intercooler, third gear would just feel dead because the IAT's would go through the roof and timing would drop drastically.

 

Black and FL, Thanks for the suggestions and help. Would it be ok if I logged a few runs on thursday and sent 1 or both of you the data?

 

plain and simple. if you're running a 4.8 with a procharger you need more stall. adding timing isn't going to get you anywhere near what you want. a 2500 stall may be good for a 6.0L, but for a 4.8L with a procharger you will need at least a 3200 stall speed to get it into an acceptable boost level for launch.

 

Sure. I'll check them out.