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See attached pic but at WOT shift (7000 or so with a 7100 limiter) from 1-2 Im getting a weird speed differential. Im dropping at least 7mph in a matter of .5 seconds then its accelerating up again. As you can see on the pic it drops mph right after the shift. Any reason as to why? I dont feel it in the truck. Rpm on shift drop goes to 5357 which is alot to me (1600ish). Maybe its right I dont know. My usual rpm differential is around 1300-1400 depending on where I shift. I know my converter slip is around 7% calculated. Maybe its too tight? Im not 100% sure what the stall is but on tbrake I can take it to 4k and thats about it. I launch at 3250. My 60' times are crap and trying to figure that out but it mph's decent on top end..... (107mph with 1.8 60' and 7.3x 660'). Sad thing is is it hooks great too. Ive had it launching on 10psi and 3500 and its same ole story. Never seen better than a 1.77 and that was last night. Hooked every time on the D06 28x10's. I know I need a C07 but I have these for time being.
1995 S10
SBE 6.0L
78/75 turbo I/C'd
Built 4L80 w/FTI Converter and rmvb
9" rear with 3.55 gears
28x10 D06
Cal Tracs
3650 with driver
No fancy suspension work. Lowered with junk comp 3 ways in rear. Belltechs up front. Hooks fine and wrinkles sidewalls. Usually run about 16psi
Crossing the 1/8 shifting right into 3rd gear
Any insight would be excellent. Im about at wits end on this. Still a learning process for me.
Damnit. I knew it was something stupid to make me look like a retard. Thanks!
On a side note do you see any reason why I should not be getting better 60' times? Is my gearing wrong? Im not spinning off the line. It hooks hard. I just dont understand why its so sluggish. So much so that I wont even watch the video my wife or son takes of it launching unless its sped up to 1.5x.....lol. Is there such a thing as too much hook? Could timing make it slow off the line? You can see timing below in pic. I think its still conservative but not sure if more would help.
Ive left on anything between 2000 and 4000. That log above is at 3250 I believe. Its leaving off the tbrake and 2 step limiter. And Ive left on as much as 10 psi but it spun off the hit and then some. That log above is leaving on 7.7psi. That was only a 1.77 60' and best to date. No slip until gear change. I just dont get it. Either my dragy is bullshitting me or something else is going on. I will say its very consistent. Consistently slow off the line.
Ive left on 3500 as well. Usually ramp boost in at 2 seconds. I will have 2 on the dome to leave and till 2 seconds. One above is leaving on 7.7 ramping to 8.5 in 1 second and 15psi in 2.5 seconds. Heres pic. I would think there is enough on there to make a better 60' time. Maybe not Idk. Still think timing is low. Ive logged a 4 second time to get from 3500 to 6900 in rpm in 1st gear.
Its dual mac valves and CO2 on dual wastegates....44mm's.
First, Can you post the RPM column along the left side too? I’d like to see what the converter is doing.
Secondly, ramp in your 15 psi in under a second. Remember until you get into some boost, it’s still only 364 cubes with a 3.55 gear and a tall-ish tire and 3650 lbs. You’re fuel usage looks decent at 650 or so. Through a 4l80e I’d say roughly 560 at the wheels.
Include the ignition timing column also.
You should post up the log and the tune for it. I'm agreeing with 3 window, but I hate looking at screen shots, I need to be able to move and load other data for my brain to think it all through.
I have a 4L80E and triple disk 3800 stall from FTI also. I am footbraking it, but can only get about a 1.52 best 60 ft with it and my car is about the same weight as yours but with a 3.73 gear and supercharger. I think FTI makes their 4L80E converters really tight. Like was said above, add some timing way before the stall speed to add some torque and try again. I am trying the same thing with mine to get it to flash higher.
What version 78/75? Still seems like too large of a drop on the shift to be optimal. Add power and RPM to lessen the shift drop. Easier than swapping the converter out or changing gearing, assuming you aren't out of turbo.
I like to put 20-25lbs in my radials and slowly bump RPM/boost/timing until you spin on the launch... Then drop pressure down to the suggested range (I run radials, and use the chart on the MT website). Usually gets me close.
06-23-2021, 04:32 PM
MPH Drop on shift? 
