Long post...What is needed to get this junk into the mid 12’s?

[F-BIRD'88]

Thats why a custom converter tech eants to know how much torque your engine makes so he can set up your cuztom buikt converter to get the max stall speed at launch that you want.. Tske that same converter and apply more torque or less torque, the max stall speed will change +/- based on torque input.
If the torque input is known and the resulting max stall speed is tested determined (on a transmission test dyno) you can calc the K-Factor for that converter.
Very few aftermarket racing converter companies own a transmission test dyno. Like GM has.

[GARY C]

The max stall you get from a converter is a direct function of the engine torque output applied.
There is about a 500 rpm difference in the max stall of a305 cid sbc vs a 350 cid engine.. With the same 10" converter.
3000 vs 3500 is typical.. Take that same 10" converter and put it behind a 454 bbc and the stall will be 4100-4200 rpm. This is how converters work.
Similar a 12" gm converter behind a 350 cid engine eill stall at 2100-2200 rpm.. Same 12" stock converter behind a 454 now, will stall at 2500-2600.
I have tested this myself eith varios gm converters behind various sbc and bbc engines.
GM defones this relationship as the "K Factor"
Thus if you know the GM K factor rating and know the engines torque output you can determine the stall speed rpm at max stall. More torque input gives higher max stall rpm from a perticular converter.
The newer GM torque converters have a 4 digit code on them. One of those digits in that code is the GM "K factor"
Google it.

Yes you can "blow right thru" a converter by applying too much torque input. Because the case distorts and the fluid cavitates. You can google that too. Fluid cavitation.

So because you have tested 1 GM converter you now are the converter know all? Oh wait, is it 500 or 1000?

Could it be the converter your testing? Or is it just your converter theory that was never actually tested?

[PRH]

Stall speed:

http://www.hughesperformance.com/tc-stall/

https://www.turboaction.com/conv_techtalk.html

K factor:

http://kennedysdynotune.com/torque-conv ... selection/

In my car, using the same 8” Dynamic converter with both a 340 and 383 Mopar resulted in a 500rpm difference in flash stall.
400ft/lbs and 5.13’s flashed 4900 with the 340, 465ft/lbs and 4.56’s flashed 5400 with the 383.

With my 9” Dynamic behind my 448 and 4.56 gears ...... swapping from bowl ported heads and a hyd cam to fully ported heads and a solid roller cam resulted in the flash stall going from 4900 to 5300.

[Steve.k]

Thanks prh! Good info there.

[F-BIRD'88]

The max stall you get from a converter is a direct function of the engine torque output applied.
There is about a 500 rpm difference in the max stall of a305 cid sbc vs a 350 cid engine.. With the same 10" converter.
3000 vs 3500 is typical.. Take that same 10" converter and put it behind a 454 bbc and the stall will be 4100-4200 rpm. This is how converters work.
Similar a 12" gm converter behind a 350 cid engine eill stall at 2100-2200 rpm.. Same 12" stock converter behind a 454 now, will stall at 2500-2600.
I have tested this myself eith varios gm converters behind various sbc and bbc engines.
GM defones this relationship as the "K Factor"
Thus if you know the GM K factor rating and know the engines torque output you can determine the stall speed rpm at max stall. More torque input gives higher max stall rpm from a perticular converter.
The newer GM torque converters have a 4 digit code on them. One of those digits in that code is the GM "K factor"
Google it.

Yes you can "blow right thru" a converter by applying too much torque input. Because the case distorts and the fluid cavitates. You can google that too. Fluid cavitation.

So because you have tested 1 GM converter you now are the converter know all? Oh wait, is it 500 or 1000?

Could it be the converter your testing? Or is it just your converter theory that was never actually tested?

Many converters tested behind many different engines.
Over many years.
Your attempts at lawyer spin just show your ignorance and add no technical merrit to a topic.

Good tech info PRH...

[PRH]

Off topic I know....... but this is another good one:

https://www.sonnax.com/tech_resources/8 ... n-and-more

[GARY C]

Stall speed:

http://www.hughesperformance.com/tc-stall/

https://www.turboaction.com/conv_techtalk.html

K factor:

http://kennedysdynotune.com/torque-conv ... selection/

In my car, using the same 8” Dynamic converter with both a 340 and 383 Mopar resulted in a 500rpm difference in flash stall.
400ft/lbs and 5.13’s flashed 4900 with the 340, 465ft/lbs and 4.56’s flashed 5400 with the 383.

With my 9” Dynamic behind my 448 and 4.56 gears ...... swapping from bowl ported heads and a hyd cam to fully ported heads and a solid roller cam resulted in the flash stall going from 4900 to 5300.

Yes a 300 to 500 flash difference is normal and why converters are rated the way they are, it's not uncommon to see one flash a little higher than it stalls against a trans brake as well.

Gear ratio can have an effect as well.

[PRH]

a 300 to 500 flash difference is normal

Normal...... for what?

My 8” gained 500rpm flash with the addition of 65ft/lbs of tq.
Behind the 448, with another 85ft/lbs it would have flashed close to 6k.
Behind a 650ft/lb 505 it would be closer to 6500.

[GARY C]

a 300 to 500 flash difference is normal

Normal...... for what?

My 8” gained 500rpm flash with the addition of 65ft/lbs of tq.
Behind the 448, with another 85ft/lbs it would have flashed close to 6k.
Behind a 650ft/lb 505 it would be closer to 6500.

We run tighter 10" nitrous converters, one rated 4500/4800 between 700 to 900 hp they flash around 4800 to 4900 maybe 5000 if you hit it with a big shot when foot breaking from about 1200 rpm.

It would flash about 4500 straight motor with engines ranging from 400 to 600 hp.

[PRH]

Using the known engine tq and stall speed from my 340 combo, my 8” converter has a k factor of 245.

If you put that behind a motor with 650ft/lbs instead of 400, the stall goes from 4900 to 6250.

I don’t know where you’re coming up with the idea that there can only be a stall speed variation of 3-500rpm for a given tq converter.

It all depends on the tq output of the motor and the k factor of the converter.
The higher the k factor, the greater the variation in stall speed with differing tq applied.

A common misconception regarding torque converters is that the stall speed of a particular converter is constant, but the reality is that stall speed is a variable as a function of the engine’s torque. The mathematical constant that decides a converter’s stall speed (in rpm) is called the “K” factor, and is derived from the observed stall speed of the converter divided by the square root of the applied torque. This relationship is expressed mathematically is: K=rpm/√torque. Once the K factor for a particular converter is determined, the stall speed can be accurately predicted for engines with different torque levels by simply inputting the engine’s torque and K factor into the equation and solving for stall speed.

Bringing this back full circle, and the reason why I was very suspicious that the OP’s converter was probably broken from the beginning......
The original combo reportedly flashed the converter to about 4000rpm.
Assuming something in the neighborhood of 425ft/lbs engine tq, the k factor of the converter would be about 195.
In order for the same converter to only stall at 3000, the engine would have to only be making 239ft/lbs tq........ which seemed a bit unreasonable to me....... with a more likely scenario being that the converter is broken.
Even if the replacement motor only made about 360ft/lbs(about 15% less than the original) it still should have pushed the converter into the 36-3700 range.

I didn’t do any of the math at that time, I just knew that a 10” converter that flashes 4000 behind a 355 isn’t going to lose 1000 of flash stall behind another 355(that didn’t look like something that would make radically less tq).
The math seems to support that premise.

[GARY C]

Using the known engine tq and stall speed from my 340 combo, my 8” converter has a k factor of 245.

If you put that behind a motor with 650ft/lbs instead of 400, the stall goes from 4900 to 6250.

I don’t know where you’re coming up with the idea that there can only be a stall speed variation of 3-500rpm for a given tq converter.

It all depends on the tq output of the motor and the k factor of the converter.
The higher the k factor, the greater the variation in stall speed with differing tq applied.

A common misconception regarding torque converters is that the stall speed of a particular converter is constant, but the reality is that stall speed is a variable as a function of the engine’s torque. The mathematical constant that decides a converter’s stall speed (in rpm) is called the “K” factor, and is derived from the observed stall speed of the converter divided by the square root of the applied torque. This relationship is expressed mathematically is: K=rpm/√torque. Once the K factor for a particular converter is determined, the stall speed can be accurately predicted for engines with different torque levels by simply inputting the engine’s torque and K factor into the equation and solving for stall speed.

Bringing this back full circle, and the reason why I was very suspicious that the OP’s converter was probably broken from the beginning......
The original combo reportedly flashed the converter to about 4000rpm.
Assuming something in the neighborhood of 425ft/lbs engine tq, the k factor of the converter would be about 195.
In order for the same converter to only stall at 3000, the engine would have to only be making 239ft/lbs tq........ which seemed a bit unreasonable to me....... with a more likely scenario being that the converter is broken.
Even if the replacement motor only made about 360ft/lbs(about 15% less than the original) it still should have pushed the converter into the 36-3700 range.

I didn’t do any of the math at that time, I just knew that a 10” converter that flashes 4000 behind a 355 isn’t going to lose 1000 of flash stall behind another 355(that didn’t look like something that would make radically less tq).
The math seems to support that premise.

Just going off of personal experience with converters that have to be able to stage on motor and then hold the tq of multiple stages of nitrous without increased slippage with each stage.
From your K Factor article.

For example, if a motor has 400 ft-lbs. of torque and stalls a particular converter at 3,000rpm, K = 3,000/sqrt{400} = 150. Since we know K = 150, we can predict the new stall speed if torque is increased to say 500 ft-lbs by rearranging the equation to rpm = K*sqrt{torque}. In this case, the new stall would be rpm = 150*sqrt{500} = 3350. This formula isn’t perfect. It won’t work if the engines have wildly different torque curve, for example.

I don't think the K Factor would work for a turbo converter either, they have to be loose enough to come up on boost with a few 100 ft lbs and then be able to hold a 1000+ ft lbs or they would just flash to infinity.

[gmrocket]

The max stall you get from a converter is a direct function of the engine torque output applied.
There is about a 500 rpm difference in the max stall of a305 cid sbc vs a 350 cid engine.. With the same 10" converter.
3000 vs 3500 is typical.. Take that same 10" converter and put it behind a 454 bbc and the stall will be 4100-4200 rpm. This is how converters work.
Similar a 12" gm converter behind a 350 cid engine eill stall at 2100-2200 rpm.. Same 12" stock converter behind a 454 now, will stall at 2500-2600.
I have tested this myself eith varios gm converters behind various sbc and bbc engines.
GM defones this relationship as the "K Factor"
Thus if you know the GM K factor rating and know the engines torque output you can determine the stall speed rpm at max stall. More torque input gives higher max stall rpm from a perticular converter.
The newer GM torque converters have a 4 digit code on them. One of those digits in that code is the GM "K factor"
Google it.

Yes you can "blow right thru" a converter by applying too much torque input. Because the case distorts and the fluid cavitates. You can google that too. Fluid cavitation.

So because you have tested 1 GM converter you now are the converter know all? Oh wait, is it 500 or 1000?

Could it be the converter your testing? Or is it just your converter theory that was never actually tested?

Many converters tested behind many different engines.
Over many years.
Your attempts at lawyer spin just show your ignorance and add no technical merrit to a topic.

Good tech info PRH...

Then I'm sure you have all that data ...let's see the "many" results .

[Stan Weiss]

Remember what the torque looks like for in this case a 300 Shoot.

Stan

ab-nit300.gif

[GARY C]

Remember what the torque looks like for in this case a 300 Shoot.

Stan

ab-nit300.gif

Not sure what I am looking at?
Here is a 350 with a 150 and a 300 shot plate and a 225 fogger, not the best attempt but I learned a little about tuning with the fogger.

[Steve.k]

What the hell does that have to do with op problems??