Torque converter lockup
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rusty_lawrence
- Posts: 119
- Joined: 2021 Jun 03, 14:46
- Location: New Orleans
- Vehicle Information: 1994 F150 Lightning
WAY1 / SMD-221 / AHAC2
408w / AFR heads / Ported GT40
Novi 2000 intercooled S/C
wbo2_aem_uego
Torque converter lockup
For my own learning.... Can someone educate me on the philosophy for torque converter lockup? I'm in a gen1 lightning with an e4od. Looks like the settings are based on mph and throttle position. Is this treated almost like an intermediate gear? like gear 2.5, 3.5? Say for WOT when is the ideal time to turn it on? In my mind, you would be far enough into the powerband where eliminating clutch slip doesnt drop you too low and out of the band?
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efloth
- Posts: 399
- Joined: 2021 Feb 15, 22:12
- Location: Sacramento CA
- Vehicle Information: 1991 F150 4.9L J1X 80lb Injectors E85
1995 F150 5.8L MOB1
Re: Torque converter lockup
I'm certainly no expert on the topic but from experience; the farther past torque converter stall you are in the RPM range the less effect lockup has on engine RPM. This is a dynamic phenomenon based on variables including engine output, vehicle weight, gear ratios, tire size, etc. In first gear above converter stall, light throttle lockup on my truck makes almost no difference.
Besides RPM and throttle position functions, there's also a minimum slip required to lock up. The converter will not lock up unless there is excess slip occurring. From my understanding, this is why the strategy has the gear ratios programmed for each gear.
When the driver is not demanding much power, leaving the converter unlocked produces some efficiency gain at low speeds since the engine is not lugging but the little power produced is still transmitted to the wheels, keeping you moving.
I have 3.55 gears and 33's on my '93 5.8l which is not ideal with my tfs1 cam. Second gear pulls strong from 35 to 90 mph. Locking the converter at around quarter throttle and 35 mph produces some nice RPM drop and improved acceleration when unloaded. I have my tune set to unlock if I push past half throttle so when loaded, pulling a trailer, or accelerating out of a sharp uphill corner, it'll kick up the RPM giving me the additional power and torque multiplication until I pass 50 mph or bring the throttle back down. It's really fun to drive and it's nice being able to control an auto this way. Hope this helps.
Besides RPM and throttle position functions, there's also a minimum slip required to lock up. The converter will not lock up unless there is excess slip occurring. From my understanding, this is why the strategy has the gear ratios programmed for each gear.
When the driver is not demanding much power, leaving the converter unlocked produces some efficiency gain at low speeds since the engine is not lugging but the little power produced is still transmitted to the wheels, keeping you moving.
I have 3.55 gears and 33's on my '93 5.8l which is not ideal with my tfs1 cam. Second gear pulls strong from 35 to 90 mph. Locking the converter at around quarter throttle and 35 mph produces some nice RPM drop and improved acceleration when unloaded. I have my tune set to unlock if I push past half throttle so when loaded, pulling a trailer, or accelerating out of a sharp uphill corner, it'll kick up the RPM giving me the additional power and torque multiplication until I pass 50 mph or bring the throttle back down. It's really fun to drive and it's nice being able to control an auto this way. Hope this helps.