stall or high stall torque converters (RE: stall convertor)

["Gary H." <spigot2039@xxxxxxxxxxx>]

Hi all,

I am posting this message for Don Dulmage, who is having e-mail issues.

Thanks,
Gary H.

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Every engine has a power band, a sweet spot or an area it runs best in. When we design or build a car we want our engine to always be in that sweet spot. If we are below the sweet spot or power band the engine will bog or labour when we pull away.We don't want that because the engine is not efficient there nor is it fun to drive. Say we have a stock engine, a 318 for instance. Let us say just for the sake of argument its power band is 1200 to 4200 RPM . Anywhere in the band it runs well. Below it labours and above is not good at all. This engine would need a converter stall of AT LEAST 1200RPM and would need gearing so it could hit 120 mph at 4200rpm if we expect it to be a normal driving car. If we gave it a bit more stall speed it would pull away a bit quicker  but it can live with 1200 stall. If we take say my 426 wedge with its 525 hyd cam and 1100 RPM idle in neutral. We know it will have no power at1200 rpm. It almost needs 1100RPM just to idle. If we put in in front of the 1200 converter above and put it in gear it would probably not be able to sustain an idle and would quit. If we try to drive it it will have to go from the 1200 farting and kicking all the way till it reaches the bottom of its power band somewhere around 3000 RPM. The top of its power band is right around  6150 RPM so we gear for 6150 at 120 mph.
Just to be able to drive this vehicle we will need a stall of 3000RPM so when the car is stopped at a stop light it can reach up into its power band before it has to pull the car away. Once it is rolling it is much easier to move then the converter will lose its stall and become relatively locked up. The speed at which this happens is coupling speed. We will be able to let it idle along at 1100 rpm and it will drive the car and allow this engine with its big cam to idle. Since we know that we might meet a Camaro or Mustang along the way we are not happy with just being able to drive it. We know that even though the engine's power band starts at 3000 it has say only 220 hp there. By 3800 it has 335 hp so we pop in a 3800 stall converter (From Frank Lupos Dynamc Converters of course)  This gives a a car that will sit at the stop light raggedly idling away at almost 1000 rpm (converter pulls it down a bit.) and when the light changes we pull away niceley with no trouble. HOWEVER! If we pull up to the light a Joe Mustang is sitting beside jacked up on his converter  with that smart ass sneer on his face we can push the brake pedal a bit harder and lean into the throttle . If we hold the brake hard enough we can push the engne to almost the full 3800 RPM and still be at the stop light. We now have available on the release of the brake the same hp as his sick little pony has on its very best day at its top RPM. Come with me now as we finish the story.The car is protesting under the strain. The light goes green and we lift the brake , The front end rises as the car leaps forward. My wife is screaming from the passenger seat shouting "I DON'T KNOW WHY YOU HAVE TO DO THAT! IT HURTS MY NECK!!!!!!" I pretend not to notice. My neck is just fine! The tach hits 6100 and I push the pushbutton marked 2nd. The shift is firm and hard.(I feel sorry as I see Linda's head snap back and forth. ("Hang in there baby!" I think." This wont be much longer!")  I glance in the mirror to make sure the back window didn't fall out on the shift. Speed builds at an incredible rate and you can now hear the wind going by the car . Once again the tach reaches for the 6100 mark and I push D (for drag)  The shift is a bit different but definite. I check the mirror. No Mustang or anything else in sight. By now my wife is pounding my arm hollering "The're gonna put you in prison one day!!!!" Satisfied all is well I lift. The car drops back down on its suspension and eventually returns to normal speed . I idle along about 30 mph .Just another old grey-haired man out for a Sunday drive in his old car. I become in an instant the poster boy for innocence. I turn to Linda and answer her first question softly with an evil grin "Because I can!" She shakes her head and wipes her brow. That my son is the stall converter story. 
When you settle down phone Frank and order one. Whatever he says you should have. Sometimes if you tell him Don sent you it saves you money so I have been told. 
Don D


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