Converter stall question

[Cudadrag]

Is the only reason for "High Stall" converts for high RPM launches? Is it correct to say use the lowest stall converter you can for your drag race launch RPM needs?

Meaning I have (Or had. I am replacing a cracked converter) a 4000 rpm stall converter. I typically set launch RPM near 3000 RPMS. Anything more really doesn't seem to improve 60 ft times. Of course the higher the Rs the harder for the line locks to hold the car. The motor rebuild is including higher compression and 500 rpm higher cam limits. (No trans break, 2-step line locks) My thoughts are to increase stall to 4500 (Since I have to replace torque converter anyways.) and increase average launch RPMs to 3500.

I see no advantage (In fact some performance disadvantages) in anything higher.

Am I thinking correctly? Or are there other considerations.

Thanks Again. This site has helped a lot on little decisions like this one. I am still investigating make and model, but before approaching any manufacture I figure I really should have a number in mind.

And if anyone has a make and model recommendation please feel free to add any thoughts.

[dirty dan]

You should consider the effects of higher stall speed. Iam talking about the down side . Not the launch changes. But the draw back.
I don't know the detail such as what your RPMs at the finish line may be.
How far are you from your redline when you go through the traps.
The thing to keep in mind is that stall speed has an effect on luanch as well as top end.
pretty much the higher the stall speed,the more top end speed you will lose to slipage.
How much do you want to trade topend for launch?

[Slingshot383]

High stall doesn't automatically mean high slippage anymore. Your best bet is to call 3 converter companies of your choosing, give them all the details of your car, and let them run it through their computer program and they'll tell you what their recommendation is for your particular combination. Then you can make an informed decision on what you want to do.

[BlackSkyRacing]

I've been pondering the effects of using an A518 (727 based) or A500 (904 based) OD unit that uses a lock-up converter... Those of us in the diesel world know that converters can be made to take some serious abuse. I guess the one thing we don't consider as much as most traditional drag racers do is rotating mass. A triple disc, billet front cover converter for a diesel weighs nearly 80 pounds. Though being that triple disc converters are required to handle 1500+ ft-lbs of torque and the A518 converters are smaller than an A618's I'd imagine that a single disc billet front cover unit for a 518 would weigh considerably less.

Though I'm not using this for drag racing, I just thought I'd throw it out there...

[Rich Kinsley]

I agree that it's best to give the converter companies your specs and have them make suggestions. The Frank Lupo Engine Dynamics converters are highly recommended by all my friends for our Mopars. They will tell you what will work best for you. And yes the slippage issue seems of less concern these days.

[Cudadrag]

You can ask 3 different companies and get 3 different answers. Most agree where I'm at is good. And RPM at trap is well over stall so should have no slipage issue. Being the motor is (or will be shortly) a different build configuration I can only guess. Rev limitator will be set to cams operational max RPM of 7500. Shifting at 6800. Launch RPM 3000. I'm "guessing" stall no lower that 4000 and no higher that 4500 (since for me there would be no benifits)