My car is at the tranny shop right now having the transmission rebuilt. I am converting the valvebody to full manual and changing the stall speed.

The transmission builder recommended I go with a 2000 - 2400 stall speed but I am concerned this is not enough. Right now I have a 2800 - 3200 converter and I hate it. Driving around town, it just feels like too much throttle is required to get the car moving decently and it heats the transmission way up to 220 - 240F if you don't baby it even with a trans cooler. My 60' times with 3.23 gears and 28" tires are 2.3 at best, which is just awful (Although I did later find out the engine was not at a proper tune due to a blown FPR diaphragm). I told the builder to go with a 2400 - 2800 converter, and I am worried I will not like this as with the one I have now.

Right now I have an 85 LB9 with a few bolt-ons, headerback exhaust and free mods. I do plan in the near future on changing my rear gears to 3.73 and going with a shorter tire. EVENTUALLY I would also like to cam the engine and swap out a set of trickflow heads and an Accel manifold. The car has also had It's weight reduced by a couple hundred pounds.

For now and the future, what do you guys think? Have I chosen the right stall speed or should I go with what the builder is telling me to?

 

Why do you hate your current one? Is it a lockup type?


Converter should be matched to motor combo and purpose.

Flashes differ when torque is applied. Same converter will flash higher on a bbc vs a sbc cause of tgorque. Smaller size diameter usually have higher multiplier and less weight.

 

Also, I couldn't even break the tires loose doing a break stand. Even with nitto drags, a TPI motor shouldn't have any issues roasting the tires.

 

What brand of converter do you have right now?

 

Boss Hog by ACC Performance. I'm going to a TSI. The following thread I made might also be worth reading:

https://www.thirdgen.org/forums/tran...rter-what.html

 

If your old 2800-3200 was a 12", then no wonder you hated it. If it was a 10", then I have no clue.

 

It was a 12" but I don't think It's that cut and dry. The B&M holeshot I had from a PO before this one performed light years ahead of this converter

 

I do. When you try to stall a 12" to 2800+, the fin angle has to go negative. It drives like hell. But it doesn't cost much to buy. To get that much stall the correct way requires a 10", so the fin angle can stay positive, like an 1800-2200 in a 12". But 10" converters cost a lot more.
The Holeshot 3000 is a 10", not a 12", so no wonder it drove better.

 

That makes alot of sense, but the converter we pulled out of the car was a 12", not a 10". I went with a slightly lower stall speed this time, BTW. 2400 - 2800.

 

What camshaft is in the engine? That will determine your stall speed requirement. For street/strip use, the stall speed should be about 500 rpm into the powerband. For full race, the stall speed should be about 1000 rpm into the powerband.

Lets say you have a camshaft with a rated powerband of 1800-6000 rpm which would be a basic street cam. A stall speed around 2300 would be the best choice. From the sounds of it, your tranny builder is offering the best suggestion.

Too high a stall speed can be just as bad as too low. The goal is to get the engine rpms into the powerband as quick as possible for best performance. Driving around with the engine operating at less than stall speed means the converter needs to slip. Slip creates heat and heat kills transmissions. Any converter with a higher than stock stall speed needs a good external cooler to help remove the excess heat.

 

I thought the main goal was to get a stall within 500 - 700 of peak torque. Learn something new every day.

Right now It's a basically stock 305 with a couple bolt ons. SLP runners and holley AFPR with headerback exhaust. I do plan on keeping the 305, but future planned mods are 3.73 gears, trickflow super 23 heads, accel tpi base and an LT4 hotcam (Or similar). Possibly a 100 shot of nitrous, but I haven't come to a final decision on that one yet. I think the risks of running nitrous are pretty considerable.

I basically want to make sure the torque converter I've chosen will suit me decently for now and match future planned mods well. This is mainly a street driven car, and does have a Hayden trans cooler with a temp gauge installed. I went with a TSI 12" 2400 - 2800 stall. If I've done my homework correctly, the shortened length of the SLP runners combined with the runners on the Accel manifold will move the peak torque a couple hundred RPM higher up. I do hope I've made the right choice...