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Discussion Starter #1
I stumbled accross this variable stall control awhile ago which I found quite interesting.
Now, I realise that they are not built for C4's at present but looking at the patent and how it operates...by controlling the amount of fluid that the converter contains via the cooler fluid circuit, I wonder what effect the pump mods we do to the C4 has on converter stall??
 

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When you "starve" the converter for fluid (to increase stall speed) I'd think you will also have some cavitation inside the converter. Cavitation will kill it faster than anything. Got to figure out a way around that.

GM used to have a TH400 that had a dual stall speed option, IIRC. I don't know how it worked or how long it lasted, but I just remember an older fellow at the drag strip telling us about it.

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<font size=-1>[ This Message was edited by: mavman on 5/15/07 6:49am ]</font>
 

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I have heard(or read) that there is a hole that can be drilled on a powerglide pump that will effect stall speed by 100 or 200rpm. I don't really know much about it.
 

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On 2007-05-14 19:01, clevelandstyle wrote:
I have heard(or read) that there is a hole that can be drilled on a powerglide pump that will effect stall speed by 100 or 200rpm. I don't really know much about it.
Converter feed hole, yes. It's common to increase the size of the holes to increase fluid flow into and out of the converter, which also causes a little bit of a stall speed change. The change in stall speed is overlooked by the fact that the converter will fill faster. Powerglides never cease to amaze me. C4's are the same way but I've never picked apart a C4 as much as a 'glide.
 

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Discussion Starter #5
On 2007-05-14 19:07, mavman wrote:
Converter feed hole, yes. It's common to increase the size of the holes to increase fluid flow into and out of the converter, which also causes a little bit of a stall speed change. The change in stall speed is overlooked by the fact that the converter will fill faster. Powerglides never cease to amaze me. C4's are the same way but I've never picked apart a C4 as much as a 'glide.
This is what I am getting at. If we modify the cooler circuit by removing the checkball/spring arrangement and/or drill the case oil feeds larger for better cooler flow.... is it effecting the converter? Does the extra flow (just like drilling the glides feed hole) decrease the stall....or put another way what effect does increasing the outlet side/flow do if the inlet side is untouched??
 

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Very interesting.Have been noticing for a while now that the converters i use from 2 different manufacturers have 4 good size holes down inside the converter,maybe to aid converter fill??? Have checked some older stall converters i have and they dont have the holes
 

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Gm had 3 transmissions that used a variable stall convertor.

Dynaflow ,ST300,Th400.

The angle of the stator vane could be controlled by oil pressure.

It worked very well, but like anything else, someone had to improve on the situation and play with it till it broke.
 

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The Pump is large enough to handle the improved cooler mods without affecting the cooler fill capacity. Remember that the later C5 uses the same pump and it comes from the factory with larger passages than we modify the C4 cooler passage for.
Paul
 
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