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Stall Recommendation
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I never looked at it in the in-depth way and terms you guys are. I just figured the "stall" rating let's say was 3000 rpm and if you floored the motor from a stand still it would maybe flash up to 3100-3200 ish rpm (with other variables changing things)depending on how much torque was pushed to the Torque converter and then maybe the multiplier part is just saying from the input shaft on the trans it sees a zero torque input then in less than a second the full torque of the motors potential plus "X" number it twisting on the input shaft for a brief moment off the line and then it's going to have the stock torque of the motor from then on and stay at the "stall rating rpm" at WOT from then on.

I may be thinking too simplistic however I have never taken the time to read into how they really work internally like you guys are now.
This below link was using the V6 TC stall rating on my old 97k1500 heavy brick with the 4l80e and whipple from a dead stop in 4HI. You can sort of see the torque converters effect on the speed and rpms from a stand still in the video if it still works.
http://s208.photobucket.com/albums/bb85/stroker97k1500/460ci/?action=view&current=IMG_1906.mp4

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stroker97k1500 wrote:
I never looked at it in the in-depth way and terms you guys are.


That's cause you're not as obssess as I am Laughing

I think the STR should be 1.9 - 2.0, close to what OEM have.
If it's less, I think it will take more RPMs to get the car going and will feel sluggish. I think that's where the STR has it's importance, in the "feel" of the converter.

Cool vajayo (video).

http://s208.photobucket.com/albums/bb85/stroker97k1500/460ci/?action=view&current=IMG_1906.mp4

You can see the work of the verter,
Stall to 3k ish rpm and stays until, 0-25mph
Then,
4k 35mph
5k 50mph

With tire size, rear diff ratio and1st gear ratio, you can calculate theverter slip

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Ok so let say the converter truly multiplies the torque by 2.0 for example.

How does that translate in the acceleration.

Let's say Robby's truck puts out 500ft-lb @ 3k and,
Tires 32", rear diff 3.42:1, 2.75:1 first gear.

@3k and 500ft-lb, the engine develops 286hp

That's important to know. No matter how much the TC multiplies the torque, you still only have 286hp available.

So you got your foot on the whoa foot on the go, engine at 3k and 1000ft-lb twisting you're tranny's interns.

Then you let go of the whoa, what happens?
Assuming you don't turn your tires into smoke, you would have 1000ft-lb of twist until the turbine reaches 1.5k rpm or 15mph.

Why? Cause 1000ft-lb at 1500 rpm = 286hp
And that's the maximum available hp when the engine is churning 500ft-lb at 3k rpm

If the engine stays @3k rpm while you accelerate, your turbine torque would drop proportionally as it's rpm climbs beyond 1.5k rpm, (to maintain 286hp) as the turbine rpm continues to increase to match the engine rpm.


You would have maximum acceleration up to 15mph and then feel an obvious gradual loss of acceleration (by half) as your speed increases beyond 15mph.

I don't think that's what happens, but if take all the info out there about STR literally, that's what it would look like.


Oh and by the way, this is why this STR torque multiplication makes me chuckle,

If in the example of Robby's truck above, he had 1000ft-lb at the trans input shaft (500ft-lb x 2.0 STR)

He would have 7,054 lbs of push:

1000ft-lb x 2.75 x 3.42 ÷ 16" × 12"

On a 5,500 lbs truck, that would mean 1 G initial acceleration and spinning of all 4 tires for the first 10-15mph!

REALLY?! Don't think so.

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The stall converter I have in my truck will be around 2400 rpms.

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No, not going to dig. I really only ever have a few minutes here and there to get on the net anymore. I clearly said that it's giving up one thing to get another, not pulling power out of nowhere. To get the extra dig on the power, it takes it from somewhere else. The extra torque it puts out on takeoff comes from cruise, as once the trans catches up to the engine it takes more power to keep it going.

You may not like analogies, but I have a better one. 10 amps at 120 volts is the same 1200 watts as 100 amps at 12 volts. When transmitting that power a long distance, you lose a lot more power on 12 volts than you do on 120 volts.

Torque converters with lower multipliers are supposed to be more suitable for towing and fuel efficiency than drag racing.

But, if my opinion is unpopular here, I'll be glad to concede the conversation. I'm simply not up to carrying arguments these days. It's not a dig at anybody or a matter of "taking my ball and going home" or anything, I'm just not up to it anymore. This job I have now beats the crap out of me mentally.

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Speeder wrote:

You may not like analogies, but I have a better one. 10 amps at 120 volts is the same 1200 watts as 100 amps at 12 volts. When transmitting that power a long distance, you lose a lot more power on 12 volts than you do on 120 volts.


This analogy I can handle cause it make sense to me and I know it to be true. Wink

Sorry Jim, I guess my own work frustrations came out in my rant on something that is complex to understand and that I think compagnies are taking advantage to hype their products.

Sorry for beating a dead horse. Sad
Just wanted to get to the truth.

Love your analogies, really, just trying to find a clear, scientific explanation of the process with data to back it up.
There is nothing out there, other than what they market. And I don't beleive marketers.

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Great video to understand the mechanics of the TC:


https://youtu.be/pTfipsejqS0


How crude they were in 1953

https://youtu.be/leCEmJA0WsI

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No worries, it really is me. Intense work stress, getting over the upper flu (we have both upper and lower flu running around Oklahoma right now), mentally I've been spent for a while now.

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Speeder wrote:
No worries, it really is me. Intense work stress, getting over the upper flu (we have both upper and lower flu running around Oklahoma right now), mentally I've been spent for a while now.

Dang the flu is awful, me and my wife received a flu shot last year now they are saying that the flu shot don't fight off the flu that's around here. Hope you'll get to feeling better!

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I always like the analpgy of slipping a 2 stroke clutch. If you are at WOT at low rpm, you are accelerating slowly, then just touch clutch while staying at WOT and you have a burst of sleep. Same or very similar process to the EFFECTS of a TC that is stalling, process is obviously different.

As to the auto vs ,manual trans question. Usually the auto trans car will have a lower mph through the 1/4 mile than a stick equipped car. This is because the efficiency is higher, or less power is lost as its a mechanical vs hydraulic link. However, the auto cars usually have the better ET, esp if its a performance TC that allows the vehicle to launch hard like a clutch equipped car.

The comparison becomes even more interesting when you take the shift time loss out of the equation, like using a sequential trans vs using your typical clutch-shift-clutch OEM style trans.

Also, remember the old 60's Nitromethane cars? They would spin the tires, while the clutch didn't slip. Then with the advent of the slipper clutch, the clutch did the slipping while the tire were supposed to hold traction. 2 different methods of accomplishing the same thing. Obviously its much safer to slip the clutch than the tires when travelling at 200+ mph.

peace
Hog

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I'm not finish with this torque multiplication misinformation that has flooded the internet mouhahahaaa. *Cough cough* Yuck

Unfortunately, I got more important things to deal with for now.l

I will say that Speeder is right about a STR that's good for acceleration will rob power at cruise and vise versa. I'll have to start a new tread with better explanations on my views.

To finish, of course the high stall auto has better initial acceleration.
Can you imagine slipping your manual clutch at 3.5k for as long as it takes for the clutch to match the flyweel's rpm! Without spinning the tires... On a 600hp car? You'd burn the clutch in no time...

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Hog wrote:
I always like the analpgy of slipping a 2 stroke clutch. If you are at WOT at low rpm, you are accelerating slowly, then just touch clutch while staying at WOT and you have a burst of sleep. Same or very similar process to the EFFECTS of a TC that is stalling, process is obviously different.
peace
Hog


Yes very similar. 2 strokes are gutless below peak torque. But you have to be very skilled to master that technique... And the wet clutch pack is similar to an auto transmission clutch.

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