Forums
New posts
Search forums
Image search
Shop
Amazon Store
T-Shirts
Stickers
Members
Current visitors
Supporting Member Upgrade
Sponsors
About
Log in
Register
Search
Search titles only
By:
Search titles only
By:
New posts
Search forums
Image search
Search
Search titles only
By:
Search titles only
By:
Menu
Install the app
Install
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Jeep Wrangler JK
JK General Discussion
2017 JKU is running hot
Reply to thread
Message
<blockquote data-quote="Dirty Dog" data-source="post: 451409" data-attributes="member: 24042"><p>Automatic transmissions do not have a mechanical connection to the engine. They have a hydraulic connection via the torque converter. This allows the engine and transmission to spin at different speeds. Otherwise, when you stopped, the engine would die, just the same as a manual does if you don't engage the clutch. </p><p></p><p>At some point, the torque converter will "lock up", which means the engine and transmission are spinning together. When this happens depends on a lot of things. But if the torque converter is locking up incorrectly, it can increase the engine load and drive up the temperature.</p><p></p><p>Lock up is also called "stall speed" or "flash speed", especially in racing circles. A torque converter with an intentionally high RPM stall/flash/lock up is called "loose". It is common practice to run a loose converter on performance cars with automatics, because when you hammer the throttle, the loose converter will allow the engine to jump up to the stall speed of the converter. This puts the engine in it's powerband immediately. Driving a car like this can feel a bit weird, because the engine will immediately jump to, say 3500 RPM, and then hold there until the car accelerates enough that the transmission catches up to the engine. At that point, RPM will start to rise.</p><p></p><p>This is the whole point behind the development of the CVT (Continuously Variable Transmission). It eliminates any gears. The engine flashes to whatever RPM is the absolute peak of the power band, and stays there the entire time you've got your foot planted.</p></blockquote><p></p>
[QUOTE="Dirty Dog, post: 451409, member: 24042"] Automatic transmissions do not have a mechanical connection to the engine. They have a hydraulic connection via the torque converter. This allows the engine and transmission to spin at different speeds. Otherwise, when you stopped, the engine would die, just the same as a manual does if you don't engage the clutch. At some point, the torque converter will "lock up", which means the engine and transmission are spinning together. When this happens depends on a lot of things. But if the torque converter is locking up incorrectly, it can increase the engine load and drive up the temperature. Lock up is also called "stall speed" or "flash speed", especially in racing circles. A torque converter with an intentionally high RPM stall/flash/lock up is called "loose". It is common practice to run a loose converter on performance cars with automatics, because when you hammer the throttle, the loose converter will allow the engine to jump up to the stall speed of the converter. This puts the engine in it's powerband immediately. Driving a car like this can feel a bit weird, because the engine will immediately jump to, say 3500 RPM, and then hold there until the car accelerates enough that the transmission catches up to the engine. At that point, RPM will start to rise. This is the whole point behind the development of the CVT (Continuously Variable Transmission). It eliminates any gears. The engine flashes to whatever RPM is the absolute peak of the power band, and stays there the entire time you've got your foot planted. [/QUOTE]
Verification
Post reply
Jeep Wrangler JK
JK General Discussion
2017 JKU is running hot
Top
Bottom