I have a 97 trans am auto and plan on building engine with LT4 hot cam, porting heads (not sure what) and LTs.
What would be the best stall for me? I want drivability.
What exactly does a stall do? (I kinda already know a little)
How does a stall act when under normal driving, does it always stall to the set RPMs?
Is it bad/harsh for a stock tranny? (my main fear)
Would you recomend building the tranny?
Would you recomend it for a daily driver?

Thanks in advance.

 

You'll probably be best off with a ~3200-3400 stall.

It basically slips more than the stock converter, until a set RPM. For example, under light acceleration around town, I used to be able to keep the RPM's at or around 2000 (with 3.73s). With the 3200 stall, I stay around 2200-2300.

When you floor it off idle, the RPM's will jump higher (and multiply the engine's torque) and the car will launch like a ****. It will really wake it up

Any mods that make more torque are bad for the stock tranny. Some people get 30k, some people get 150k before a rebuild. I would recommend getting a built tranny (can't hurt I got mine through Frank @ Cahall Performance Transmissions and couldn't be happier), and yes, it's fine for a daily driver.

Make sure you get a lockup converter, so after a certain speed, the converter locks and there is no slippage regardless of the stall speed.

 

the torque converter obviosuly converts torque. the whole idea is to try and get the motor to it's peak or at least closer to peak torque band to increase acceleration. the higher stall you go, the more slippage you have. Cmr0Z28 described it well.
"It basically slips more than the stock converter, until a set RPM. For example, under light acceleration around town, I used to be able to keep the RPM's at or around 2000 (with 3.73s). With the 3200 stall, I stay around 2200-2300"
is it bad for the tranny? yes and no. mechanically, no its not. but it does create more heat within the transmission, so an aftermarket tranny cooler would be advised. They are reasonably priced as well. you should understand this though... by "slipping" we mean the torque converter, not your bands and clutches in the transmission so dont think it will wear it out more. a good tranny cooler and you shouldn't have any problems with overheating. as far as a stall goes, i'd go with a 2800-3200 max. 3200 is a pretty big stall and fits nicely with the hotcam setup, but you don't excactly need it. I've driven a hotcam car (stock heads) with a 2800 stall and it was a nice stall. put it right in the torque range. Obviously, the higher you go in stall, the less streetable it becomes. if it's a daily driver that you're not super competitive with, i'd go with a 2800 stall. you might gain a tenth or 2 from a 3200 over a 2800 stall in a hotcam car, but it's a question of how much it's worth it to you. with any kind of stall, you will lose gas mileage due to higher rpms when the converter is unlocked, but it's not an ungodly amount. again, the higher you go in rpm means the less mpg you will get. There are many variables, but the two i listed seem to be what most street guys consider most important. it's just a matter of what you're comfortable with. either way, an auto with a stall is awesome, especially out of the hole. i love my 6 speed, but a high stall car sounds great through town. make sure you get a lockup converter.
on the transmission...a stock 4l60 wont hold up to that much power for very long. usually they last about 6 months in the daily driver who goes to the strip and races around on the street occasionally. it's best to get it built if you have the cash. plus, once you get the shifts shortened and hardened, it'll improve your heat issues and produce wheel spinning 1-2 shifts. SWEEEEET

 

o, and i forgot.... it produces these expressions

 

Thanks for explinations. I think I understand now. I guess I'll go with a 2800 stall and a built tranny. How many tenths in the quarter do you think I would pick up with the set up I said above?

 

its hard to say since you don't have any idea of the engine's power output yet, or any baseline runs with the new motor and without the stall. I'd guess around 5 tenths between the stall and the tranny build on your setup. I'd think with some sticky tires, as in BFG drag radials or some ET street like tires you can net low 12's easily. the car i drove was a 3.42 geared 2800 stalled, shorty header, hotcam car on stock heads, internals, and compression. it is a full weight car with all typical bolt on and suspension mods to make it hook. the owner netted a best of 12.39@ 108 (on ET streets) last time i heard. this time was recorded in indiana, so not too far up in altitude. consistant 12.5 and 12.6 car in most any weather conditions. He now has lt4 heads, but i have'nt been able to keep in touch with him to see if he's got any new bests. another local has a similar setup, but with really good ported heads and a 3200 stall. he was getting around 12.10's @110 last i heard in the heat of the summer. overall, it'll be a fun setup. beats most of the crap you see in the streets, but there's always a bigger fish somewhere.