ok time to stop the confusion i personally built this converter using a 10 inch c4 core so it's stall should be the same as those found in a 10 inch c4 converter
it is not a reworked stocker obviously as it is a 10 inch converter
there really aren't any components in that converter that can fail it has the largest sprag ever built by ford good for about 700hp
all the fins have been reinforced
and it is completely rollerized
i have decided to no longer build these aod torque converters there is too much confusion and everyone thinks they have gotten a faulty unit even when it works exactly as it is supposed to
i question if the clutches in your transmission can handle the blow of the extra torque multiplication which could cause sloppy shifts
and i also wonder if your band is working properly if the band slips 2nd gear would not pull hard causing the feel you are getting around 30mph
that converter is built to be efficientand should be near a 1-1 ratio by 3800rpm however it does not pull hard below 1800rpm as i told you in the first place
if the stall is too much send it back i'll swap in a low stall stator but you'll have to pay shipping both directions because i didn't make profit from this converter anyway all the parts in it are new from sonnax and i put at least 10 hours of labor in this thing believe it or not building that precision front cover was alot of work
for future reference the only converters i will build for aod transmissions are those identical to pi or edge converters using a complete kit from sonnax and the cost would be about 650 dollars
if you want to go with one of those send me that converters back and i'll refund the 150 you paid for that converter from the cost

Confused?
 

Is this convertor supposed to stall around 3000 or is it 3800 (nominally)?

Rev

it stalls to 3000 it is at maximum effieciency at 3800 max meaning at 3800 rpm it should deliver a 1-1 ratio

Flash stall?
 

I thought that if the flash stall occured at 3000, then the convertor was "coupled" and delivered about 90-95% efficiency from there on out to red line.

From your description, I'm wondering what happens beteen 3000 and 3800.

Rev

it becomes more efficient the closer it gets to 3800 and 3800 could be a high figure on that it could be most efficient by 3400
the true stall of this converter after flash has occured is about 2700
like i said before this converter shares all of the stall controlling components with a 10 inch c-4 converter i have not modified any of those components except to make it work with an aod transmission which with 2 input shafts is a tough job

For his applcation....right?

As goes for a converter with 90-95% effieciency...wouldn't that be a real effiecient converter? I generally thought when you got a loose converter (3,000++) your level of effieciency would be at best 10% after stall speed unless you spent the big $$?

i didn't build this converter for his application i built it for a friends car and they decided it was too much for their daily driver so i built them a 12inch converter instead .

i could spend hours explaining torque converters to you and still most would not understand what i am saying without seeing it so i'll start and finish it up later.

the parts of the converter.

pump or impeller pictured here on the right.

and the stator is on the left on top of the turbine.

these components control stall and efficiency this particular model is built for the 4r70w and aode transmissions.

the pump has a few factors controlling stall and efficiency
the angle of it's blades (this is a very high stall unit) control stall alot .
if the blades are straight stall will be less and if they are pitched the opposite direction they will be even lower.

also it's diameter and depth control stall this is a deep converter which will become very efficient (90%)at high rpm but is not very efficient at low rpm.

the stator is the aluminum piece you see it has a sprag inside of it that turns freely one way and not at all the other.
when the sprag is locked the converter is on high stall.
when it is unlocked the converter is as efficient as it can be.
the fin angle of the stator greatly increases stall as well as the distance the stator is from the turbine and impeller further away from the impeller will decrease stall and further away from the turbine will increase stall.

the turbine is the other set of fins you see it drives the input shaft of the transmission.
the depth of the turbine also helps control stall and efficiency as well as brazing of the components as you see here improves efficiency.
the distance the turbine and impeller are away from each other greatly controls stall and efficiency
normal clearance is .100thousandths or 1/10th of an inch
converters can be built as close as about .060 thousandths but they have to be very precision parts and usually the brazing process time and use and even factory standards don't much allow for these clearances the easy way to make a converter stall is to add clearance between the halfs at 3/10ths of an inch a 1500 stall 90% efficient converter will become a 2500 stall 75% efficient converter compared to the 1/10th of an inch normal clearance
however making stall this way has the most dramatic influence on efficiency so is not desirable the best ways to increase stall and to machine the stator to allow more flows but redirect it away from the turbine or just use a stator that is already the way you want it
and changing the angle of the pump or impeller fins is a good way to increase or decrease stall that is the most common thing to do to get a mild change the stator generally makes a major change

i thought i added the picture last time but here goes again

here is a better picture of the turbine and the opposite side of the stator

to answer your question, P.I. stands for Precision Industries www.converter.com
Ryan

I was told that you could tell the stall speed of a TC by power braking slowly up until the tire break free and that is about 2300-2500 RPM. Is this correct for a 3000 RPM TC?

Thank you

No thats incorrect way of checking....to many variables....road surface, tires, traction, rear brakes, suspension, etc.

One way is to use a trans-brake, another would be to drive the car and see how high the rpms flash right before the car takes off. The only problem with that is people will start to blow the tires off before getting a good reading on the tach. So most people check thier stall while on the chassis dyno if they don't have a trans-brake. From an idle they will just stand on it and see how high the rpms will climb intionally before it will "REALLY" start to excellarate the wheels on the dyno.

I guess that would be true, too many variables. I know that when I get on it, it breaks the tire free relatively easy. Before they would barely break free and now I can be running at around 40 mph and punch it in drive and I see 2 black marks as long as I stand on it.

It's getting much better.

John

try to flash the converter to get the stall figure you are looking for

How do you flash the TC?

do the stall test but do it fast so the converter doesn't have time to build pressure

Are you talking about power braking?

yes

What are "black marks"? Oooooh, you mean rubber.

Isnt torque braking really bad for the converter and the brakes?

power braking just generates heat so it's not good to do alot but it is how you test the stall