stall converter
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Cargo Master
Joined: Mar 2008
Posts: 2,409
Likes: 1
From: Goliad, Texas
stall converter
<TABLE id=HB_Mail_Container height="100%" cellSpacing=0 cellPadding=0 width="100%" border=0 UNSELECTABLE="on"><TBODY><TR height="100%" UNSELECTABLE="on" width="100%"><TD id=HB_Focus_Element vAlign=top width="100%" background="" height=250 UNSELECTABLE="off">I read on a thread about a week ago that someone bought a truck and wanted to know how to figure out what stall converter they had on the vehicle. I think the thread said to put the truck it gear and then hold the brake while pressing the gas and watching the tach to see where the truck stalls and then you have your answer. well I was just wondering how do you figure it out if you have a manual transmission? wouldn't it stall when you hold the brake since the truck isn't moving but it's still in gear? cause you can't hold the brake, clutch, and gas all at the same time if your stopped.
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Senior User
Joined: Oct 2006
Posts: 277
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From: The Casa
"Stall" refers to the Rpm at which the torque converter transmits the engine's power to the transmission.
Kinda like a go-karts clutch.
manual transmissions don't have a torque converter,because the engine and trans become locked together when the cluth is released.So your launch RPM will be determined by when you release the clutch.
Kinda like a go-karts clutch.
manual transmissions don't have a torque converter,because the engine and trans become locked together when the cluth is released.So your launch RPM will be determined by when you release the clutch.
More Turbo
Joined: Jun 2006
Posts: 601
Likes: 0
No way to tell the stall using the brake and flooring the gas. Stall is affected by many different things. Torque having the most effect. What you see when you push the brake and floor the gas, is the RPM in which the converter "flashes" with that particular motor. The higher the torque, the higher it will flash. If you swapped that same converter into another vehicle, it would most likely "flash" at a different RPM, even though the converter is rated at the same stall speed.
Elder User
Joined: Nov 2005
Posts: 597
Likes: 0
From: San Antonio, TX
I have a related question... Where do you want the "flash" to occur? I have a 351w, with a torque peak of 320 at 3000 RPM. It's a street truck that I like to push, but never haul anything. I'm assuming because my torque is down low, I don't need a higher stall speed than what the stock torque converter has, but I've been told otherwise by one person. Just wanted to get some opinions from here.
Senior User
Joined: Oct 2006
Posts: 277
Likes: 0
From: The Casa
i am really not an expert,but as far as I understand on a street vehicle you want a stall speed that is close to cruising RPM as possible.That way when you are crusin your torque converter will still be getting the power to the pavement.Also if you get too high of a stall speed,the takeoffs will get squrily.
i'd probably go with something like 2000-2500,that way at takeoff you'll hit the engines's "Sweet Spot"
i'd probably go with something like 2000-2500,that way at takeoff you'll hit the engines's "Sweet Spot"
Lead Driver
Joined: Jun 2006
Posts: 5,635
Likes: 963
From: Near Yosemite CA
I would stick with a stock spec converter, you can find billet ones, and numerous upgrades, but it all reality, you don't NEED a stall converter unless you are into high perf running. The higher the stall speed, is the higher the rpm before it fully "locks, or engages" very similar to "dumping" the clutch at a set rpm, except with a tc you do have some slippage/engagement before it fully hooks up.
You have to understand that a torque converter is just a viscous coupler, the fins on the inside on one side are bolted to the engine i.e. the tc bolts that attach to the flex plate, and the other side is a direct connect to the tranny, the engine side spins and the tranny fluid is caught in between the 2 sets of fins, and starts to force the tranny side fins to spin in turn moving the truck. Once it is at the "stall speed" it locks together and spins equally, no slipping and transfers all the power through. That is why an automatic trannys worst enemy is heat, the fluid is heated through the "slipping" process of the fins.
You have to understand that a torque converter is just a viscous coupler, the fins on the inside on one side are bolted to the engine i.e. the tc bolts that attach to the flex plate, and the other side is a direct connect to the tranny, the engine side spins and the tranny fluid is caught in between the 2 sets of fins, and starts to force the tranny side fins to spin in turn moving the truck. Once it is at the "stall speed" it locks together and spins equally, no slipping and transfers all the power through. That is why an automatic trannys worst enemy is heat, the fluid is heated through the "slipping" process of the fins.
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Elder User
Joined: Nov 2005
Posts: 597
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From: San Antonio, TX
I know how it all works, I just wasn't sure if it was worth upgrading. My truck is my toy, so I tend to drive it differently than my daily driver. I want it to be fun to drive.
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Postmaster
Joined: Feb 2003
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No way to tell the stall using the brake and flooring the gas. Stall is affected by many different things. Torque having the most effect. What you see when you push the brake and floor the gas, is the RPM in which the converter "flashes" with that particular motor. The higher the torque, the higher it will flash. If you swapped that same converter into another vehicle, it would most likely "flash" at a different RPM, even though the converter is rated at the same stall speed.
BTW, I absolutely despise the prhase "I installed a stall converter". It says absolutely nothing. ALL torque converters have a stall speed.
More Turbo
Joined: Jun 2006
Posts: 601
Likes: 0
What you've said is true, but wouldn't the "flash" rpm be the "stall speed" or "stall rpm" of that particular combination? As you said, the torque output of the engine can cause the actual stall rpm of the converter to be different than the rated rpm. The rated rpm is pretty much a number made up by the manufaturer for comparison shopping. It would be useful to know what input torque they used to develop the rating. speed.
