Jamesbond2509

iTrader: (1)

I basically had the same problem with it running like a dog at launch after my 4l80 install. I fixed it with tuning and 4:10's, now she barks on a roll at 7 psi on 33inch tires! Im currently working on fabbing up an intercooler; hopefully that will get even more umph at launch.

dewmanshu

iTrader: (4)

I have been playing around with Zip's IAT tuning scenario for awhile and defintiely found how much it works, but I must add, I still believe there is something to the burst knock. Anticipated knock by the pcm right? You don't see it as kr on the scanner, you have to pid it. I definitely found with cool IAT's and heavy 4wd launch it is usually sluggish versus 2wd or a part throttle launch. Most of the time, not always. I am definitely onboard with heat though, not dissing that idea, that's for sure. Just I think there is validity to "numbing" your burst knock tables.

F8L Z71

So you find that launching in 4wd tends to cause the burst KR more often than launching in 2wd?

Ohh, thanks aain for putting together that video for everyone. I really enjoyed it

dewmanshu

iTrader: (4)

no prob!!

Again...sometimes. Unfortunately, I don't have as much time as I'd like these days to experiemnt like most of you, but I have to say dumbing down the burst knock helped me...I have nothing in offical numbers or facts to back this statement. Just wanted to extend on what Thunder started with. It almost seems like the converter or trans just slips through the first 60' then it takes off. Looking at my logs, I am not getting the timing I am commanding. And when I do get the timing I command, launch is good.

F8L Z71

That is EXACTLY how my truck feels. Even on the street or from a 30mph roll or so it downshifts to 1st and just revs up but feels like a dog till you hit 2nd gear and it jumps forward. You think this is all due to the burst KR?

dewmanshu

iTrader: (4)

All? No, I think zippy has nailed alot of it, IAT. But you can't resist to think something is going on when temps are good, my 80e is praticaly new, converter is new. I don't see any harm in turning down burst kr for research purposes, do you?

I just don't think you can blame that sluggishness on a mismatched cam and converter flash. I am nobody to be giving advice in this area, but for troubleshooting purposes, just how much can 600 to 800 rpm of short flash take away from your launch. Now heat on the other hand...ofcourse. But you can see that with logs. But a fresh (no high IAT's) launch and still slow off the line...makes you go hmmm.

The 13.5, what was the biggest difference in the logs? Timing? You already cooled it down right? Have you ever messed with your burst? Are the tables stock? Just my 1 cent. I don't have enough knowledge to give another penny.

F8L Z71

I dont have any loggin equipment so I dont know what was going on other than AFR and fuel pressure :p

The first runs were when it was still hot out and runs were within 15-20 minture sof eachother without any real time for a cool down. IE the water in my Radix coolant tank was still really hot as was the blower itself.

My runs where I trapped 103-104 were after over an hour long cool down and the blower was only warm to the touch and the engine had cooled considerably. I know that isnt scientific at all but its all I hard to work with since I lost my Autotap cable and dont own EFI Live or anything.

As for my tables. Im not sure what all has been done when Rick tuned it. It wasnt a full blown tune because my MAP sensor wasnt working right so I am on a speed density tune but with a 1-Bar MAP instead of a 2-Bar and we knew I would be back for a real tune after I did the 90mm TB and H/E upgrade. Im trying to schedule an appointment with him to get all this worked out and get this pig running correctly.

Whippled 496

iTrader: (4)

well, like i said....my KR is MUCH more obvious (on the log) from a 4hi launch than it is from a 30mph roll. Almost non-existant on the 30mph roll, but i could bet the farm its gonna pull out 5* almost every time from a 4hi launch. I have never tried to log it from a 4hi launch when its had a considerable cool down, but thats gonna be next i think. All this, keep in mind, AFTER we have zero'ed out the burst knock table and lowered the KR sensitivity....nothing changed at all in the log. I really think my KR issue is due to IAT's (more demand on the blower from a 4hi launch?). Nothing scientific about my theory other than the my best run at the track came after almost an hour of cool down time. My last run on Friday, i actually had a little bit of wheel spin in 4hi and still managed a 1.90 60' time with a 7000lb truck, thats how good the launch felt. I never got that before i installed the larger pulley, but i am certain that the larger pulley is giving me higher IAT's. It will be interesting once i get the I/C installed, to see how my truck respondsand if the KR comes down.

dewmanshu

iTrader: (4)

again I agree with both...heat and burst. I would definitely agree heat (IAT) is usually the culprit. Usually.

F8L Z71

Well hopefully this new mod will help cool things down at the track where I really need the power. I have enough on the street so Im not as concerned with that. Im thinking Im gonna have to stock up on like 10 or more of those ice packs as that water is gonna get warm fast lol.