All about torque converters and locks!
Thanks to Blackbird for the nice writeup.......just thought I'd share his wealth of info with the rest of you who have questions
1. With a 3800 stall whats it gonna be like to drive on the street? I'm guessing it'll rev to like 2300rpm before start to creep along............ Its not bad at all. I love my 4k I wont go back. The High stall helps with turbo lag, you get a better power band. The High stall means that at 2300 rpm the car will not move as fast as when you have a lower stall. Our cars dont produce good power below 35k so you want to rev to 35k as fast as possible. The higher stall will require Extra tranny coolers to keep the heat down. And you will want to lockup the converter when going up long hills or at constant speed driving to keep the heat down.
2. Converter locks........what exactly are they?
. The Converter has a Clutch plate like a manual trans that when engaged locks the to sides of the converter together so that they dont slip. You will need to lockup the converter on the dyno to get good numbers. A lot of people dont like autos because without the lockup, the converter will always Slip and you will lose power. At the strip I lock up the converter in high 2nd or third gear about the 1/8th mile of the track.
3. I hear WOT and locking the converter is no good, but how about for just regular driving around the city or rush hour traffic? Isn't it alright since you are only going at partial throttle?
Around town is fine and is a must to keep the heat down. I lock mine up alot on the street and the strip. I only have about 400rwhp with a built tranny so im not worried about breaking a sprag in the tranny. With 500 plus HP I would be careful. My new tranny requires me to manually shift when racing, Transwerks has a custom mod to help take pressure off the sprags when I manually shift.
4. With the lock will the car move more like stock and then when I'm trying to race or just cruising on the freeway turn the lock off?
. On the freeway turn the lock ON. It will help keep the heat down and you will get better gas mileage.
5. Can you please send me your diagrams again of how you did your lock with your stock ECU
6. The lock is just something you make right? Not something you have to go and buy.....besides a few odds and ends from like a hardware store?
all you need is a solenoid, wire, and some connectors.
A Torque Converter is fluid-filled case that contains a set of turbines - there is an input turbine that is driven by the engine, an output turbine that connected to the transmission's input shaft, and a stator turbine between them that directs and controls the flow of the fluid.
At a certain input RPM, the torque converter will reach its maximum fluid flow. Below this input RPM, there is poor hydraulic "coupling" between the input turbine and the output turbine - there is a lot of "slippage". Above this input RPM there is a hydraulic "lockup" - there is almost no slippage between the input turbine and the output turbine. This certain input RPM is called the "stall speed" of the converter. This property of a torque converter allows an engine to rev-up to a speed where it begins to make significant power (commonly referred to as "torque multiplication") before being put under a heavy load. The stall speed of a torque converter needs to be carefully matched to the torque curve of the engine it will be used with. A high-performance or race engine, which makes power only at high RPM, needs a torque converter that has a very high stall speed.
You cannot check the stall speed of a torque converter by pulling the transmission into gear, holding a vehicle with the brakes and adding power -- the drive-wheels will begin to spin long before you reach full-power. The proper way to check the stall speed is to make a standing-start, abrupt, foot-to-the-floor acceleration run and note the RPM shown on the tach at the instant the vehicle begins to move. This test actually measures "flash stall", but this is usually very close to the true stall speed of the converter. Also, this test is only valid if the tires do not begin to spin and if the engine can develop sufficient torque to actually reach the rated stall speed. If the tires spin, the apparent stall speed will be high. If the engine does not develop sufficient torque for the converter, the apparent stall speed will be low.
Some torque converters have an internal, hydraulically operated "lockup clutch" in them. At some preset point, the transmission will cause this converter lockup clutch to engage in order to mechanically lock the input turbine and the output turbine together. This improves the vehicles efficiency a bit because the slight slippage between the input turbine and the output turbine is eliminated. As a side benefit, some "engine braking" is also available when you take your foot off the accelerator.
The internal parts of the turbines are manufactured from formed sheet metal vanes and machined rings. In most "stock" quality torque converters, the assembly of these parts is primarily accomplished by interlocking mechanical means. In high quality, heavy-duty and high performance torque converters, the turbine assemblies are completely welded or furnace brazed together to provide for a stronger and more robust unit.
As with the rest of the transmission, excessive heat and contamination is what will kill a torque converter. Since the fluid in the torque converter is ATF supplied by the transmission, wear particles and/or bits and pieces of a blown-up transmission will end up in the converter, thereby destroying it. Changing the ATF at regular intervals and installing an external transmission cooler will lead to maximum torque converter life. If an in-radiator transmission cooler fails, ATF contamination with engine coolant will destroy a lockup torque converter.