6L80E WOT shift points > Based on RPM or Speed > which is it ?

[Turbo6TA]

2011 Corvette, LS3, A6 ... Supercharged, Cammed, Headers, 2,800 Stall Converter, Dyno Tuned

I just did a scan of a couple of WOT runs with a 2-3 shift and a 3-4 shift. Both shifts happen at a max engine speed showing 6,750 rpm ... I don't want to spin the engine this fast and need to slow down the WOT shift to a max engine speed of about 6,400 RPM

But, I have a couple of questions about all this:

1. Looking at the 'Full Throttle Shift RPM' tables, I see that the shifts are now set to 6,400 RPM ... Why would I be seeing a max engine speed of 6,750 RPM at WOT before it shifts ?

2. There is also tables to set the 'Full Throttle Shift Speed' ... I am confused ... When at WOT, does it shift based on what's set in the Full Throttle Shift Speed or in the Full Throttle Shift RPM tables ?

3. When setting either the Full Throttle Shift Speed or the Full Throttle Shift RPM, there are 'Normal' tables and there are the 'Pattern A' and 'Pattern B' tables ... what's the difference ?

Thanks a bunch for any help you can provide.

Ron,

[kevin87turbot]

It actually references both the Full throttle shift rpm tables and the full throttle shift speed tables. Once both of those parameters are exceeded, the TCM commands the shift.
The Normal table is the typical mode. You can hover over each mode with your cursor and it'll give you an idea of when they are used.

Google the term Bluecat spreadsheet and download it. That will allow you to calculate the appropriate shift points for your transmission, gear ratio, tire size and required shift points.

[Turbo6TA]

kevin .. Thanks for the info.

From what you said, both the RPM and Speed you set in the tables need to be met before the trans makes the shift ... So, at WOT, even if you are at or above the shift RPM you have set, it will continue spinning up the engine until the car hits the MPH you have set in the tables (if in fact, the mph is set higher than the rpm)

BTW ... here is what I have set for the RPM and then for the Speed ... I brought the RPM down to 6,200 rpm so it would not blow too much past that 6,200 rpm ... I just don't want to see 6.750 RPM anymore.

I will check out that "Bluecat".


RPM


Speed

[hjtrbo]

How I understand it and my a quick look at my logs seem to corelate, is when WOT, the speed will set the clutch fill etc up in anticipation of the shift and then at the RPM it will trigger the shift.

Try it for your self and see what you find.

E.g, if you're 3rd gear hit the limiter at 6,500rpm at 90mph, then set the WOT mph to 82 and shift RPM to 6,400. Add PCS1-5 channels to the scanner and see if lines up. I bet it'll shift bang on 6,400rpm +/-50rpm.

Then if you have it at bang on 6,400rpm, creep up on the mph 1 at a time until you lose the shift. Thats how I do it.

[Turbo6TA]

Thanks hj ...

I am thinking that they made this whole tuning thing too damned complicated ... I think the EPA is to blame for these car manufacturers needing to over-engineering all this.

[Turbo6TA]

Well, I just finished using that BlueCat to determine the shift speeds to apply to the tune .. I highlighted the areas that has the info I need for the shift speeds:

With my car weight and RWHP, I chose a shift lead time of 3.75 (hope that works out)

1-2 Shift: 35 mph
2-3 Shift: 68 mph
3-4 Shift: 110 mph
4-5 Shift: 149 mph

[hjtrbo]

To long lead time. I spent alot of time with mine, here is what I ended up with. It was dead nuts.

edit: Mixed up mph and kmh on the HPT screenshots but you get the idea

[Turbo6TA]

Ok ... I lowered the Lead Time from 3.75 down to 2.75

This raised the speeds between gears a little when upshifting at WOT.

Thanks for the help on that.

[Turbo6TA]

BTW ... Any idea as to what that "D RPM" is in that BlueCat program ?

Mine was automatically set to 9,900 rpm ... I just left it that way. Changing it didn't effect any of the data I was interested in anyway.

[hjtrbo]

If you hover over the name it gives a description. I've never used it either.