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HI LO Stall Converter ?
What are guys talking about when they say a High Stall converter?
Thank you Joe. |
The torque converter allows the engine/trans to "slip" while in gear and stopped. (like holding in the clutch) The higher the stall of the converter the higher the engine will rev before the car starts moving.
This is sort of over simplifying it, but what it does is allow the engine to quickly rev into its power band area more quickly. If you had a clutch and wanted to launch the car hard you could let the clutch go at whatever RPM you wanted to. With an automatic trans you can powerbrake and rev the engine, but it will only go so far, and the engine boggs. A higher stall converter will allow the engine to rev to a higher rpm and just like the manual trans you can launch the car harder. If you want to know what rpm your converter stalls at, hold the brake firmly and mash the gas pedal. The engine should "flash to it's peak rpm (allowed by your converter) before the engine starts to load up. A higher stall converter is less friendly on the streets and creates much more heat in the trans. Remember every modification you do to your car has other effects on other parts as well. Where you improve performance in one place you may sacrifice elsewhere. Every aspect of the car, and every modification is a compromise. The engineers that design and build our cars make the best balance of power, handling, economy, ride, and overall performance. When you modify one you will lose somewhere else. How's that? A school teacher I aint! Can anyone describe it better? |
a stall converter dont "lock up" untill it reaches its lock up speed, if you have a stall converter with a stall rating of 3800 it wont lock up till it reaches the 3800 rpm. (3600~4000) it will move the car under that rpm, think of it as a clutch that is slipping and then you release the pedal then it totally engages, it does help a vehicle to get off the line.
theres more to a converter than just picking out a stall converter, you could pick out a 2400 stall and it may totally lock up at 1500 of not untill 3000, many varibles are to be considerd before just picking one up. my best advice is to talk to a manufacture like ACC "boshog" or hughes, |
Thanks guys. I was thinking along those lines.
When power braking my truck, she stalls out around 1300 rpm. So I could assume that the stall of this converter (727 trans) is around 12-1300 rpm, does that sound right? Is changing out a converter a big job? Thank you Joe. |
Originally Posted by Barfly
(Post 55995)
Thanks guys. I was thinking along those lines.
When power braking my truck, she stalls out around 1300 rpm. So I could assume that the stall of this converter (727 trans) is around 12-1300 rpm, does that sound right? Is changing out a converter a big job? Thank you Joe. |
Originally Posted by Crazy4Carz.Com
(Post 55993)
The torque converter allows the engine/trans to "slip" while in gear and stopped. (like holding in the clutch) The higher the stall of the converter the higher the engine will rev before the car starts moving.
This is sort of over simplifying it, but what it does is allow the engine to quickly rev into its power band area more quickly. If you had a clutch and wanted to launch the car hard you could let the clutch go at whatever RPM you wanted to. With an automatic trans you can powerbrake and rev the engine, but it will only go so far, and the engine boggs. A higher stall converter will allow the engine to rev to a higher rpm and just like the manual trans you can launch the car harder. If you want to know what rpm your converter stalls at, hold the brake firmly and mash the gas pedal. The engine should "flash to it's peak rpm (allowed by your converter) before the engine starts to load up. A higher stall converter is less friendly on the streets and creates much more heat in the trans. Remember every modification you do to your car has other effects on other parts as well. Where you improve performance in one place you may sacrifice elsewhere. Every aspect of the car, and every modification is a compromise. The engineers that design and build our cars make the best balance of power, handling, economy, ride, and overall performance. When you modify one you will lose somewhere else. How's that? A school teacher I aint! Can anyone describe it better? Very nice Steve! |
:(i suck
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Joe -
If you built the engine right all the "parts" should come on around the same power band (rpm range). You basically want a stall converter with a stall speed at the beginning of that power band for optimal RACE performance. Or you can call B&M and discuss what you've got and they will suggest a stall speed that will work for you. Archer |
Ya, I did not build the engine. I really have no idea what's in it other than the research I have done and how it runs I'm guessing it pretty much stock. However the PO did have some nice parts attached to it. Mickey Thompson aluminum valve covers, electronic rev limiter, Mopar Performance electronic ignition - cap - rotor and plug wires, Edelbrock Torker 340 aluminum intake, Carter 600 cfm AFB carb, electric fuel pump and regulator. So it's always made me wonder if there was anything done internally to the motor I should know about.
Another thing that has always made me wonder about this motor is the oil pressure. Whether it's been 80 deg outside or 60 like recently, the oil pressure starts out a 60 lbs at idle and takes awhile to come down. Eventually after she is good and warm it comes down to 15 lbs at idle and around 40 lbs running down the highway. I guess it's good, never burns any oil, but kinda seems high don't you think? Joe. |
That 15 at idle would scare me a little.
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a rule of thumb is 10lbs oil pressure per 1000rpm and your good.
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Originally Posted by 1966sportfury
(Post 56050)
a rule of thumb is 10lbs oil pressure per 1000rpm and your good.
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Joe -
The one thing you didn't mention was the cam, and that kinda determines the engine's power band. Without taking the engine apart to check on the cam, anyway you can dyno it to see where the power band is? Otherwise, you're kinda guessing. Archer |
Originally Posted by Barfly
(Post 55995)
Thanks guys. I was thinking along those lines.
When power braking my truck, she stalls out around 1300 rpm. So I could assume that the stall of this converter (727 trans) is around 12-1300 rpm, does that sound right? Is changing out a converter a big job? Thank you Joe. the engine will have to rev a bit more to get the truck moving |
Getting closer to getting this done.
To recap my setup: I'm estimating the truck weight at approximately 3300 lbs, 340/727, 3.55 gears, Edelbrock Torker 340 single plane intake, Holley 650 cfm D'pumper, dual exhaust with stock exhaust manifolds, as far as a I know stock cam and other engine internals. I want to be able to drive the truck around town and back and forth to the city, but I also want a good launch at the track. The converter that's in the truck now (stock I assume) stalls at about 12-1300 rpm when power braking it. Here is a link to the Converter I'm looking at. I don't know what if anything, I would need besides the TC it's self ? Any opinions would be greatly appreciated. Thank you Joe. |
that looks like a decent converter, you will need a weighted flex plate if your engine is externally ballanced. i had a 2400 stall behind a well built small block and a mild BB drove just fine.
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