Lockup of 4L80E before OD

[DeltaT]

Steve and anyone else,

You mentioned:


And I'm experimenting with locking up the converter well below the 3-4 shift points.

I wondered how it is working out and what tips you might have. I have a Hughes-built 80E and the TCI T-Com. I've played with the other things you mention, with great results.

Also, any tips on a dyno session with one? My last session, on the 3rd (no cooldown between runs) run, I enabled the Lockup at WOT box, with the lockup mph set at 45mph, and I got another 35rwhp (peak 501rwhp) and 28rwt (peak 470rwt) out of her. I wonder if I should lock it up earlier (at a lower mph) for the dyno.

Also, how about the lockup parameters like lockup speed or any others? Find anything interesting?

I have upgraded from the Vortech S-trim @ 7.2# for that dyno session, to the T-trim, and with some drive belt layout changes (another idler before blower, better wrap, stronger tensioner), I am getting 10.75# @ 6200 out of the blower and plan to dyno again soon. I'm hoping to break 600rwhp on pump gas.

Converter is a Hughes 2500-rated lockup.

Thanks in advance,

Jim

[Steve Chryssos]

You can basically lock up anywhere above stall speed. Do the math on stall rpm in high gear as compared to mph, then find the matching higher speed in 3rd gear and set lock-up there. All said and done, I did not like lock up too low. We have the ability to tune in some slip--unlike a manual. Might as well use it. If youhave a beefy enough clutch, try locking up at low speeds. You'll probably go back and raise the speed.

[ty1295]

In turbo application we lock them up as early as 2nd gear to load the motor and make the turbo sing. Really depends on the truck, motor, redline, etc.

[DeltaT]

Thanks. It sounds like it would be worth it to keep a file/setup for track use only. Do you guys change setups for conditions, or just find an optimal one and stick with it?

Also, any tips on the lockup speeds - raising, lowering, effects, etc?

I appreciate it.

Jim

[DeltaT]

Anyone?

Thanks,

Jim

[hotrdblder]

one tip is to make sure you have a special built tq convertor with large lock up disc or you will be burning the clutch up quickly, that leads to me saying to talk to twist as they have custom designed tq convertors with large lock up clutch with heavy duty material, just so you can lock it up down low, i have driven a car with this convertor and i can tell you it rocks, also they are known to add 20-30 rwhp as they are so much more efficient then the typical drag race style convertors we all know.
goodluck

[Steve Chryssos]

We only have one, optimized map. For situations outside of the optimised map, (i.e. wheel spin, wheel hop, downshifting) we have the paddle shifter.

As for lock up tuning tips, they are listed above in post two Set as low as possible above stall speed and then raise from there.

[DeltaT]

Thanks. I got the speed as in mph stuff before - now I am talking about the lockup speed as in the PWM time that's programmable in the T-Com. It comes stock set at 64. Higher is a faster lockup. I wondered if any of you have played with higher values and if it gets harsh at some point? I would think, like most auto tranny shifts, that a faster engagement means less clutch or band material wear, and maybe a slightly better time, at the expense of maybe harshness.

Thanks,

Jim

[Steve Chryssos]

Yeah, it'll get harsh which could promote wear. In the TCI software, just leave that number alone. The PCS software has a graphical tool that lets you adjust apply and release as a ramp.

All this assumes that you have an upgraded lock up clutch. OE style lock up clutches (about as thick as a shoelace) are really just designed for use under low load situations such as light throttle highway cruising.

The lock up clutches in all three Twist house cars are at least an inch wide and made of a ceramic impregnated material. Heavy duty stuff.

[DeltaT]

I'm just running a Hughes lockup converter with a 2500 stall speed. Nothing too special.

I'm thinking I better upgrade quickly before I start messing around with the nitrous on top of ~600rwhp. What would a converter with a similar stall but with the heavy duty lockup cost, ballpark?

Last time when I locked up under WOT on the dyno, I got another 35rwhp and ~25rwt, but it didn't lock until like 5000rpm in 3rd, which is way higher than 45mph that it was set to.

Thanks,

Jim