JDMC5

iTrader: (3)

I'm in the middle of my 4L80 swap and I'm wondering what the rpm drop will be after the 1-2 shift.

Mods are in signature ~400-420 wheel hp LS1. I'm running a 245mm (9.5") converter which should stall about 3600-4000 rpm. I'm shifting at 6600 rpm. According to my estimation I should see roughly 4400-4500 rpm. What do you guys think? Also, what are you seeing after your shifts?

Jake's Performance

iTrader: (2)

Sounds about right but the converter has a big effect.

JDMC5

iTrader: (3)

Effect on rpm drop?

I've seen people with a similar setup to mine only drop to 5000 rpm, is this possible too?

Jake's Performance

iTrader: (2)

Yes,
The converter effects the rpm drop.

JDMC5

iTrader: (3)

Yes I realize this. I was hoping you could tell me more specifics about how stall rating isn't the only factor on what determines shift recovery.

Or maybe some people could comment on prior experience with 3600-4000 stalls in a 4l80

Jake's Performance

iTrader: (2)

Converter build can affect the shift recovery. Stator selection, internal clearances, and other factors can affect it.

You can have a similar stall speed but have a converter that pulls the engine down more above the stall speed.

mrvedit

Its much more than just the advertised stall speed which will determine the-post shift RPM. One factor is the elusive "STR". I'm barely a converter neophyte, but I would expect a high STR converter to have a lower RPM after a shift than a lower STR converter.
This thread might help you understand the many variables:

https://ls1tech.com/forums/automatic...str-guide.html

JDMC5

iTrader: (3)

Thanks, good info.I will try to dig up those numbers.

Irregardless it should be in the 4300-5000 rpm range which I'm perfectly fine with.

kinglt-1

iTrader: (26)

I have a FTI 3800 with a 2.1 str...my rpm only drops to 5000rpm on a 6200 shift.

JDMC5

iTrader: (3)

yea a friend of mine has a yank 4000 and it drops to 5400 on the 2-3 shift with a 6600 shift point, 4L60. IDK what the 1-2 is it can't get traction yet. I hope mine is close, I love that stall.