For example:

A Hard-Hit 4,000 rpm converter to me feels drastically different than a Soft-Hit 3,600 rpm converter.
Only 400 rpm difference, but the stall torque multiplication ratio difference makes the behavior of these 2 converters different from one another.

The Hard-Hit unit will multiply the initial torque to the wheels more greatly... but will be less efficient near peak HP rpm. (less HP to the wheels).
The Soft-Hit unit will have less initial torque multiplication to the wheels... but be more efficient near peak HP rpm (more HP to the wheels).

Now there is a lot more going on here... but this should be simple enough to follow.

I personally prefer the "Soft-Hit" units for my street cars... I would rather have the HP up top, than have more traction issues down low.
I would probably say I would prefer the "Hard-Hit units for my race cars... but my race cars use a clutch with a lenco... O well.

Hey Dalton!!! Do you make a torque-converter for a Lenco-Drive?

 

Good post, nice simple explanation ove the difference between hard hit/ vs / soft hit.

 

Hard hit-drag strip choice-for sticky slicks for better 60-also since it's less efficient at peak means more heat generation-good at the line but loose thru the traps-most races are won at the launch.
Soft hit-should probably be called normal hit as soft hit could be taken as 'loose' by some-street use but ok to use on strip-good thru the traps.

 

The increase in torque multiplication from a higher stall-torque ratio is created by the design of the stator as it redirects fluid coming off the turbine. At high turbine to stator speed differences, this means more torque output, but when they are coupled near the same speed, it costs efficiency. A stator that has less impact on the fluid path at high speed differences won't have as hard of a hit, but it will couple better.

The fluid used plays in part in this also as the fluid's relative density, viscosity, and pressure-viscosity coefficient play a role in how much the fluid drives against the turbine and stator. If you've ever felt like the "hit" of the converter has gotten softer after repeated hits without cooldown, that's because the fluid is getting too hot. It kills me with guys sitting on a transbrake for 4+ seconds, at 50+*F temp rise per second, then wonder why the car won't 60ft well. This all effects the charge pressure. With high STR converters, I like more viscous synthetic fluids in the 7-9 cSt range where as lower STR converters I like a less viscous 5.5-7 cSt range synthetic. I always want a higher flashpoint as well, preferrably >450*F. Most of your common Dex III and VI fluids are in the 380-430*F range. ACDelco synthetic Dex VI is ~420*F, Valvoline MaxLife M-V is 398*F, and Mobil 1 is 428*F. Compare that to Amsoil Signature Series ATF at 453*F and Red Line D6 ATF at 465*F.

 

Are you implying amsoil and red-line are what people should be running?

Because that flash point isn't a big deal. How many converters have you seen spontaneously combust?
All of these fluids will Coke long before anything else happens. You can typically smell it before you see it on a dipstick.
walmart dex3 has been successful in units over 1400hp in my experience.
John Deere HyGard, in my opinion, is one of the best fluids on the market for the money. It's very temperature stable, lubricates VERY well (I can tell by how bushings look on refresh), doesn't coke easily but is easy to tell when it does thanks to its pale color...very foam resistant, etc.

If your transmission builder does his job right...he won't give a **** what kind of fluid you run. He will care how MUCH you run. Proper fluid level and making sure you never starve the pump is way more critical than weather you pay $1.75 per qt or $12 per qt

 

Lenco drive, ty-drive, big shaft powerglide/th400 we do converters for all of them.

 

As long as the fluid is not foaming from aeration... then that fluid is fine.

 

Probably a bit tight for you but just saw this on FB. Pretty good deal... (no affiliation with this guy)

 

thank you for all the help and advice!! A lot of great information.
I found that the car has a RPM TRANSMISSION and a YANK ST 2800 converter. I emailed YANK, Unfortunately this converter can not have the stall speed changed. Until I can get some $$ saved up, what can I expect from running the 2800 stalled converter in the meantime?
thanks!

 

You are going to get many different opinions from everybody...

Based on the camshaft specs and the little info I found on your vehicle...
I would say that something aprox. 3,600 RPM would be a good choice.

Honestly though; there is no 1 answer... different people prefer different torque-converter STRs and stall speeds.
Read what I had typed in Post #41.

 

So you're stuck with a ST 2800 convertor for now. If it's 'tight' as the SS series is, you'll probably won't find it objectionable. But then a ST 2800 wouldn't be as low performance as the factory OEM 1800. Just hope it's not as 'loose' as the comparable TCI 2800 'Breakaway'.

 

no doubt. I realize I won't be getting the most out of the motor With the 2800 stall but will the car have good street manner..not sluggish with the 2800? The 2800 is only temporary but in the meantime I'd like to be able to drive and enjoy the car.

 

Right... quite the conundrum

 

https://ls1tech.com/forums/market/1940302

 

Not a conundrum (a confusing and difficult problem). You'll find out when you drive it, shouldn't be 'sluggish' with the 2800, just that you'll want more.

 

I may have found a solution. Found a ss4000 yank in my price range

 

thanks Tyler, I did see that! Nice deal.