Converter principles

[just plain john]

I didn't want to gunk up the tech forums with such a basic question, so I'm going to post it here. I'm trying to gain a better understanding of stall and how it effects spool up. I'd also like to know more about lock up/non lock up and why one is preferred over the other. Any opinions welcome and thanks.

 

["Turbo-T"]

Correct me if I'm wrong but my understanding is since spool is dictated by exhaust gases, a higher stall converter, depending on engine torque, will allow the engine to get to a certain rpm quicker, allowing a bit more exhaust gas out the heads to the turbo, and therefore spool up would be quicker.

I'll let someone else chime in on lock up/non lock up.

 

[just plain john]

What I'm confused about, stall wise anyway, is why a higher stall is needed with a larger turbo. I don't argue with your theory, but a stock turbo doesn't require additional stall speed so why does a bigger turbo need it? Thanks for the reply.

 

["Turbo-T"]

What I read was a bigger turbo has a bigger wheel and needs more exhaust to spin it. And a smaller turbo is the opposite.

 

[Fast4Ward]

the end

 

[bison]

The converter also needs to work with the cam lobes and couple at the correct rpm if it is going to be effective in keeping the engine where its making the most power as long as possible. Finding a converter that does all of this is not that easy.

 

[just plain john]

Ok, so lets say I swap to a 3200 stall convertor. How does this not effect driveability in streeter car? Or does bigger wheels in the turbo offset the difference? I've learned that it's important to match the size of the turbo to the stall speed, but I've never had anything but stock convertors in every car I ever had.

 

[JT'sV6]

Think of it this way, an engine is an air pump. Pulls oxygen into a combustion chamber and ignites it to make a charge. The by-product of that charge also has energy "exhaust gas". The more rpm the engine is turning, the more air is being pumped, the more energy is exiting the engine. Some turbine wheels just need more energy to spin them. Of course there is more to an efficent setup like cam, c/r, head flow, intake volume, etc... to get the right stall for your setup.

As for lock up I was told in another thread that it makes for a more efficent drag setup, I dont know about that though.

I've always been told lockup effects crusing. Lock up converter uses a clutch, do away with that clutch and it makes for a stronger unit. I would not put a non lock converter in my car unless it were drag only, but thats my prefrence.

Go to youtube and find out how tq converters work if you dont know already. A lot of great videos about tq converters.

btw...what turbo are you looking at?

and btw....I'm running a 3500 stall and it does good on the street. The only difference while crusing is you have to give it a little more throttle to get it going. The difference at the track is about half a second in the 1/8th mile.

 

[just plain john]

Sorry for the slow response. I'm not looking to change anything just yet, just gain a better understanding of how a higher stall is a benefit. Higher stall equals higher trans fluid temps, correct?

 

[Dusty Bradford]

Bigger turbos need more rpm to begin building boost. A higher stall will affect the driveability somewhat and create a little more heat. It's all part of upgrading turbo's.

 

[just plain john]

We've never spoken Dusty, but your name is well recognized. When the time comes I will seek you out.