Hot Rods Should have gone with a stall converter ?

I'm sure you older guys remember slipping in a Vega converter for a cheap way into a stall converter, the problem was they liked to burnout pretty quick because they couldn't handle V8 power for to long, but when they worked, they worked.
I was glad you guys got that crazy statement that a higher horsepower car would stall less sorted out, as soon as I read that I'm thinking here's a guy copy and pasting "I seen it on the internet" information.
When I got my 41 together I bought my buddy's converter that didn't work for his drag car, even though we both had blown 540's it was just two totally different combinations, she was a loose goose for me. Whenever I would hit a small hill the rpms would wing about 4800 as it would hunt, trying to lock up, man it was a long summer driving that baby. This is what it was out of

View attachment 4555163

Over the winter I pulled it, had it cut apart, no anti ballooning plate and fins almost completely straight (the reason it was loose and constantly hunting) so I had it totally rebuilt and reconfigured for my application. I gave the builder my dyno sheet, weight of vehicle and rear gears to get the party started, my engine make 640 ft lbs of torque at 2500 rpm and carries over 700 ft lbs from 3000-5500, now it's pretty easy and enjoyable to drive.
But that t-bucket is something else...lol

 

As usual a thread goes into the weeds looking for some arcane technical answer. The o/p says in his later post that he has to stand on the brakes to slow it down. I would suggest he has more of a brake problem.

All my rides with automatics “pull” in gear at idle. Higher stall only means a power transfer at higher rpm.

 

At most transmission supply houses, they sell a B17? convertor. It's a little higher than stock but not something radical. It's roughly 1700 rpm. They are cheap. They may even be the same deal as the Vega convertor.

 

Not really.






Bones

 

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

 

Quoted from that site
Something as seemingly simple as an incorrectly tuned idle and/or part throttle circuit in a carburetor or incorrectly tuned ignition timing can have a dramatic negative impact on the stall speed characteristics of a torque converter.

 

That is why I am going with incorrect idle speed (tach misread).

I have never seen a torque converter with a 650-750rpm stall speed.

"Something as seemingly simple as an incorrectly tuned idle and/or part throttle circuit in a carburetor or incorrectly tuned ignition timing can have a dramatic negative impact on the stall speed characteristics of a torque converter."

I have built numerous engines with LSAs as low as 106º, but all of those had manual transmissions.

 

Gimpy,
Is it pedantic yet?
Squirrel said, in post #6, to get the idle rpm down to 500 - 600 rpm.
You and I have both pointed to that as being the starting place for diagnostics. And 6Sally6 even explained how to get the carb in the ball park.
97 posts and we still don't know what the idle speed is or was.
I shoulda knowed that it needed a stall converter.

 

Ring around the rosey,

stall speed ain't so cozy,

Pedantic, pedantic,

The wheels go 'round...

Just sayin, or singing, or...ah fugg it, what's the damn idle speed?

 

Boneyard51 - not sure about your “not really” comment. I did edit my observation about the purpose of higher stall.

I refer you to post #72 where the o/p makes note of his brakes.

It does seem to me that many threads go off on a tangent rather than address the problem. To me it is like someone asking what time it is and they end up getting an explanation of how a clock works. I hope the o/p solves his problem.

 

How about "patina angle"! I'm betting that pinion angle has a lot to do with this. Discuss....

 

well, yeah. Somewhere in there, he found out what time it is, although finding it amongst the rest is not easy

 

Kool, proartguy! I agree with you now!
I agree this post has drifted from the OP’s question, but it was answered in about the first ten or so posts, his idle rpm is too high!

But... I kinda enjoy these threads that kinda drift, grow a life of their own and wonder into interesting areas....... you have to admit.....simple “ too high idle rpm”........is boring! Lol








Bones

 

The OP idle speed is 800 rpm's in park / neutral
In Gear 500 @ the point motor almost shuts off.

the OP is working on some Issues & working threw them , He is a Older gentlemen up there in age ,

I have personally ran a vega converter in vehicles with
""Big trains coolers "" ( Heat Kills) in 406- 468 cid SBC /BBC Street drive grocery getter's ,weight of vehicles 2,800 to 3,400 pounds ,with 3:55- 3:10 gears , 28-30 inch tall tires Speeds of all combos over 100 pulse MPH in 1/8 naturally aspirated with No issues with a Vega converter, 350 & 400 transmissions. Over30 years , & I also run custom Coan behind my 2,000 hp combo .
BUT Failure /Problems (Vega converters) on the Juice over 175 shot or Blown over 10 psi .

 

Page 4 and nobody has said "K-factor". Anyone who runs a torque converter could benefit by getting their head around K-factors. It's far more useful to specify a converter by K-factor than by some nominal stall speed.

K-factor equals stall speed in rpm divided by the square root of the torque at that engine speed in lb.ft, and is ordinarily a constant for any given torque converter. Look it up; fascinating stuff.

 

In this case, with the original question asked, K factor is probably not going to be listed in the specs for the few different stock or slightly modified converters he'll be looking at using.

 

Of course in the case of a stock converter that can be calculated from the stall speed and torque of the stock application.

 

That does sound interesting Ned, I will definitely look it up.

Maybe that will help me understand the previous issue I'm still struggling with, how increasing the power/torque of an engine will result in a higher stall speed. That still doesn't make sense to me in theory. If due to modification an engine now produces more hp/torque at the same rpm as before the modification, than that means it makes the same hp/torque at a lower rpm than it did prior to the modification. Which means the TQ should overcome the resistance to movement EARLIER in the RPM range, not later. What am I missing here, must be something simple I'm over looking.

 

I think you're confusing how the car accelerates, with stall speed. Remember, stall speed is measured when stationary.

 

Well, it is important to be using the same definition. If we're just referring to the highest rpm the engine will achieve against a fully stalled converter, with no output to the transmission, than it makes perfect sense.

But I think the guys who corrected me were using the term the same as I was, more like what is sometimes called the flash speed, i.e. the rpm the engine reaches under acceleration from stopped or a low speed until the TQ fully engages and the input & output are equalized.

Or even, as Hot Rod put it here: "Effective in-vehicle torque converter stall speed is defined as the rpm the engine can reach with the brakes locked and the transmission in gear before the drive wheels turn. "

 

True enough,..and we haven't talked about stators much either. But remember..we started with the o/p's "stall converter" and it went from there. K factor might be too much to digest here, still. We're still calling them "stall converters" on page four.

 

I think most of us understand that when someone talks about a torque converter, it's either "stock", or it's a "stall converter". The "high" is implied.

Not to be pedantic

 

Blues man, A couple points.

Blues man, A couple points.

Typical hot rod modifications almost always move the torque and HP numbers up the scale. Big carbs, bigger intakes, increased duration camshafts, headers, all do that..Hence the need for a higher stall speed.
I suppose a longer stroke might increase the torque across the board, but generally not the case here.

Also, one must remember that we're dealing with a fluid coupling. More torque will shear the fluid coming off the impeller and going into the turbine, more readily. Therefore you would need more rpm to create more fluid force.

Someone mentioned low stall vs. high stall OEM converters.. This is why V8 cars would call for a more positive fin angle impeller, and 6 cylinder cars would call for a higher stall converter. The idea was that all combinations of daily drivers would end up with an efficient stall speed somewhere in the 1400-1900 range.

 

Thanks Mark. In the one case I noted, the issue was with power adders, i.e. N2O. With nitrous activated the stall speed went from 3500 to 4000. I assume nitrous would increase torque as well as HP at all engine speeds, correct? Again, a lower stall speed would seem to be natural, but the opposite is reality.

I suppose it could be the issue you mentioned about shearing of the oil, that is the one thing that would result in a difference. I the viscosity of the oil remains the same, then the added power could over ride the ability of the oil to transfer power. OK, I could go with that.

So then oil viscosity would affect the stall speed as well, which makes sense.

Sorry, just thinking out loud here....

 

I don't necessarily disagree here..and we've had this discussion before.
If someone says they are going to put a cam in their hot rod, we would assume they already have a cam of some sort in there.
I would imagine if someone said they were going to put a converter in their car, we'd assume it meant higher stall.
When I hear " a stall " or "a stall converter" , it just makes me wonder if they actual understand how they work.
The TC is kind of a black art thing, seeing that you need special equipment to work on them. I've meet many great , long time racers that don't understand how they work either. Everyone seems to be an expert on Holley carbs , due to the fact that you can work on them with hand tools.
Meanwhile , I still haven't heard anyone say they're going to put a " lift " in their motor /engine.

 

Yes, correct on that last point . Lately I've heard of some racers using hyd. oil for tractors i.e. John Deere fluid, to tighten up stall speed just a bit. I suppose it would have that effect, but I would think it would be a trade off with e.t. loss on the other end of things.

...And yes , nitrous applications do require a tighter converter from the basic setup "on the motor".

 

Most of us don't understand how most of this stuff really works. We just understand that Racer Joe put one in his car, and his car is FAST! so we gotta do it, too

 

Ever drive on snow?
Think of what’s going on inside the converter between the turbine and pump like it’s traction or friction or sticktion
Tacking off In the snow by applying low power light throttle and vehicle moves and tire slippage is minimal. Attempting Hard acceleration and adding more power and the vehicle goes nowhere because the slippage ( traction or lack of it) actually being the same but can’t hold the increase in power.

The torque converter is probably one of the most complex parts on your car. Few moving parts but vary the inputs and things change, vary the parts and things change. All that on top of the bell curve changes already happening as RPMs and torque input rises.

What’s that gooyie stuff that gets hard when you hit it?