themealonwheels

iTrader: (20)

Let me start by saying this is my first experience with a built tranny and a stall. I posted in the tuning section for some input, I've done some research and taken it to a local shop for insight, but I need some closure on a few open questions.

The car is a 2000 B4C with a mild 346 (LS6 cam/intake, 243 heads milled to ~10.8:1, TSP long tubes, Magnaflow catback, boltons). The tranny is a sponsor built unit and the converter is a "2800 billet stall" according to the vendor. Here's a quick video I made of the car's behavior on a cool morning drive home.



See how it flys up to ~2500rpm and just slowly creeps up to 40mph? Then how it slams into lock-up? I hate that. This car was built to be a DD, not an "I'm going to race you, world" car. This converter was suggested as a DD stall by the vendor. Mileage right now is, like, 14mpg and I'd be surprised if I had 380whp.

So my unanswered questions:

1) Is this a symptom of a "loose" converter?
2) How do I adjust the tune to make this lock-up happen when it's supposed to?
3) How can I make this more like a stock converters behavior without a stock converter?

Thanks in advance for the advice!

mrvedit

Looks pretty normal to me for a high stall converter.
Actually it looks very loose, but then I suspect you have a 2.73 rear end which makes the converter act looser.

But, I know little about converters.
What do others think?

Gearstar Performance

This is not a symptom of a loose converter. In our opinion, it is the way the trans was built for the lock up to be on/off instead of the pwm. The tune could be adjusted for the lock up to come in later possibly 50 mph instead of the 40 mph then it may not seem as abrupt as it is.

mrvedit

True that the trans now has a abrupt on/off lockup. The Transgo and Sonnax shift kits get rid of the PWM (gradual) lockup and replace it with an on/off lockup. For one thing the PWM lockup valve tends to wear, causing slippage and a ruined converter. While a careful rebuild of the valve body can restore the PWM like new, some (many? most?) performance converter manufacturers suggest on/off for the lockup.

As mentioned, the lockup can be tuned to turn on at a higher speed. Of course that may reduce your mileage even further.

themealonwheels

iTrader: (20)

Whoops, I should have mentioned the rear gear is currently a 3.23 and will soon be a 3.42. The car is tuned for a 3.42, so the speedo is a little off.

Alright, this is good info, thanks!

Now that we've established that the converter is at fault (actually confirmed, I had a ride-along a few days ago), is that 2000 stall I purchased going to make the mileage come back? And will it "soften the blow" of the lock up if the lock up is a function of a shift kit?

Gearstar Performance

Yes, going from a 2800 stall down to a 2000 stall will help the mileage - somewhat. It will soften the blow going into lock up some. But it may still be somewhat abrupt.